NEET PG psychiatry questions

Schneider's first-rank symptoms include specific passivity and perceptual experiences believed to point strongly to schizophrenia: audible thoughts, voices arguing or commenting, somatic passivity, thought withdrawal, thought insertion, thought broadcasting, delusional perception, and made feelings, impulses or acts controlled by an external agency. Thought broadcasting, the belief that one's thoughts are being transmitted or known to others, is one of these core phenomena. Loosening of associations and flattened affect are Bleuler's fundamental symptoms, not Schneider's. Social withdrawal is a negative symptom and not part of Schneider's list.

• A. This is one of Bleuler's four A's, not a Schneiderian first-rank symptom.
• B. This is a nonspecific negative symptom, not a first-rank symptom.
• D. This is a negative symptom and part of Bleuler's criteria, not Schneider's.

The mesolimbic dopaminergic pathway, projecting from the ventral tegmental area to the limbic structures including the nucleus accumbens, shows excessive dopaminergic activity in schizophrenia, and this hyperactivity is thought to underlie positive symptoms like hallucinations and delusions. In contrast, the mesocortical pathway projecting to the prefrontal cortex is believed to be hypoactive, contributing to negative and cognitive symptoms. The nigrostriatal pathway regulates motor function, and its blockade by antipsychotics causes extrapyramidal side effects. The tuberoinfundibular pathway regulates prolactin secretion, and its blockade causes hyperprolactinemia.

• A. This pathway regulates prolactin secretion and is unrelated to positive symptom generation.
• C. This pathway controls motor function and is unrelated to positive symptom generation.
• D. Hypoactivity, not hyperactivity, of this pathway is linked to negative symptoms.

Cotard syndrome, also called nihilistic delusion, is the belief that one is dead, does not exist, or has lost one's organs or blood, often leading to severe self-neglect including refusal of food. It is seen in severe depression, schizophrenia, and some organic brain conditions. Capgras syndrome is the belief that a familiar person has been replaced by an identical-looking impostor. Fregoli syndrome is the belief that a persecutor is changing appearance or is disguised as different people the patient encounters. Reduplicative paramnesia is the belief that a place has been duplicated or exists in two locations simultaneously.

• A. This involves belief that a familiar place exists in duplicate, not a belief about being dead.
• B. This involves belief that different people encountered are actually the same person in disguise.
• D. This involves belief that a known person is replaced by an impostor, not a belief about one's own death.

Delusional disorder is characterized by one or more non-bizarre delusions persisting for at least 1 month, in the absence of prominent hallucinations and with relatively preserved functioning outside the area directly affected by the delusion, unlike schizophrenia, where functional deterioration and other first-rank symptoms are typically prominent. This patient's circumscribed persecutory delusion without hallucinations and intact occupational and social functioning points to delusional disorder. Duration alone does not distinguish the two since both can be chronic. Sex, age, and occupation are not diagnostic features for differentiating these disorders.

• A. Occupation is not a diagnostic criterion for either disorder.
• B. Demographic factors do not differentiate these two diagnoses.
• C. Both delusional disorder and schizophrenia can have a chronic course, so duration alone is not discriminating.

Waxy flexibility (catalepsy) is a catatonic sign in which the examiner can reposition the patient's limb into an awkward posture that is then maintained for an abnormally long time, as if the limb were made of wax. This patient also demonstrates mutism and negativism, which is resistance to instructions or attempts at passive movement, as seen when he keeps his mouth shut against the examiner's attempt. Echopraxia is the imitation of the examiner's movements. Automatic obedience is excessive, robotic compliance with simple instructions, the opposite of what is described. Stereotypy refers to repetitive, non-goal-directed movements.

• A. This refers to repetitive, purposeless movements, not persistence of an imposed posture.
• B. This refers to exaggerated compliance with commands, the opposite of the resistance and persistence of posture seen here.
• D. This refers to mimicking the examiner's movements, not maintaining an imposed posture.

A lorazepam challenge test, typically 1-2 mg given intravenously or intramuscularly with reassessment after 5-10 minutes, is the recommended first-line diagnostic and therapeutic step in suspected catatonia, as a positive response, meaning significant improvement in catatonic signs, supports both the diagnosis and the treatment strategy of continued benzodiazepines. Antipsychotics such as haloperidol can worsen catatonia and risk precipitating neuroleptic malignant syndrome, so they should be avoided until catatonia resolves. Electroconvulsive therapy is highly effective but is reserved for cases that fail to respond to adequate benzodiazepine trial. Oral medications are often impractical in a mute, immobile patient and antipsychotics are not first-line in this context.

• A. This is reserved for cases refractory to benzodiazepine treatment, not the initial step.
• B. Antipsychotics can worsen catatonia and increase the risk of neuroleptic malignant syndrome; they are not first-line.
• C. This agent carries the same risks as other antipsychotics and is not appropriate as a first step, and the oral route is impractical in this mute patient.

DSM-5 requires at least five of nine characteristic symptoms to be present during the same 2-week period, representing a change from previous functioning, with at least one symptom being depressed mood or loss of interest/pleasure (anhedonia). This 2-week threshold distinguishes a major depressive episode from transient sadness or adjustment reactions. The symptoms must occur nearly every day and cause clinically significant distress or impairment. Shorter durations do not meet criteria even if symptoms are severe, while the 2-week window is the standard cutoff adopted across major textbooks.

• A. Too short; does not meet the sustained symptom duration required by DSM-5.
• B. Exceeds the minimum requirement; not the threshold specified in DSM-5.
• C. Exceeds the minimum requirement; not the threshold specified in DSM-5.

Atypical depression is characterized by mood reactivity (improvement in mood in response to positive events), along with hypersomnia, hyperphagia or significant weight gain, leaden paralysis (heavy, leaden feelings in the limbs), and interpersonal rejection sensitivity. This pattern is the reverse of melancholic features, which include insomnia, anorexia with weight loss, and mood that does not improve even temporarily with positive events. Atypical depression responds particularly well to monoamine oxidase inhibitors. Recognizing this subtype guides both prognosis and treatment selection.

• B. Catatonic depression involves psychomotor abnormalities such as stupor, rigidity, or mutism, not present here.
• C. Dysthymic disorder refers to a chronic low-grade depressive course lasting at least 2 years, not a symptom subtype defined by reactivity or appetite changes.
• D. Melancholic depression presents with insomnia, anorexia, and a mood that does not react to positive events, the opposite of this case.

The monoamine hypothesis proposes that depression results from a functional deficiency of monoamine neurotransmitters, primarily serotonin and norepinephrine, at key synapses in the brain, particularly in circuits regulating mood, motivation, and arousal. This theory arose from observations that drugs depleting monoamines (such as reserpine) could precipitate depressive symptoms, while drugs that increase monoamine availability (such as tricyclic antidepressants and MAO inhibitors) improve mood. It remains the foundational rationale for most first-line antidepressant pharmacotherapy, even though current understanding recognizes additional contributions from neuroplasticity and neuroendocrine factors. This hypothesis directly underlies the mechanism of action of SSRIs and SNRIs.

• B. The hypothesis proposes deficiency, not excess, of monoamines, and dopamine/acetylcholine are not the primary monoamines implicated.
• C. Altered GABA-A receptor density is not the mechanism proposed by the monoamine hypothesis of depression.
• D. NMDA receptor overactivity relates to newer glutamatergic theories (e.g., ketamine's mechanism), not the classical monoamine hypothesis.

In a normal dexamethasone suppression test, exogenous dexamethasone suppresses pituitary ACTH release through negative feedback, leading to low morning cortisol. In severe melancholic depression, hyperactivity of the hypothalamic-pituitary-adrenal axis can override this suppression, resulting in a persistently elevated cortisol level, termed non-suppression. This finding reflects dysregulated HPA axis feedback rather than a specific diagnostic marker, and the test is not used routinely in clinical practice due to low sensitivity and specificity. It has more historical and research significance in understanding the neuroendocrinology of depression.

• B. Adrenal insufficiency would cause low baseline cortisol, not failure of suppression after dexamethasone.
• C. Altered dexamethasone metabolism is a recognized confounder but is not the primary interpretation taught for this classic finding in depression.
• D. Normal feedback would result in adequate suppression of cortisol below 5 micrograms/dL, which did not occur here.

This patient has severe depression with catatonic features (mutism, poor intake) and active suicidality, constituting a psychiatric emergency with significant physical compromise from dehydration. Electroconvulsive therapy (ECT) is the treatment of choice in such cases because it produces a rapid antidepressant response, is highly effective for catatonic and psychotic depression, and can be life-saving when oral intake and safety are critically compromised. Medical stabilization with intravenous fluids must occur alongside urgent psychiatric intervention, as waiting for oral antidepressants to take effect over weeks would be unsafe given the acute risk to life. ECT bypasses the delay inherent to pharmacotherapy and is indicated for treatment-resistant, catatonic, or imminently life-threatening depressive presentations.

• A. Psychotherapy alone is inappropriate for an acutely life-threatening, physically compromised patient requiring rapid intervention.
• C. Oral antidepressants take several weeks to act and outpatient follow-up is unsafe given active suicidality and medical instability.
• D. Lithium is not an acute antidepressant treatment and requires days to weeks of monitoring, unsuitable for this emergency.

Selective serotonin reuptake inhibitors (SSRIs) act by selectively inhibiting the serotonin transporter (SERT) on the presynaptic neuron, blocking reuptake of serotonin and increasing its availability in the synaptic cleft to enhance serotonergic neurotransmission. Because they have minimal affinity for muscarinic, histaminergic, and alpha-adrenergic receptors compared to older agents, they have a more favorable side-effect profile with fewer anticholinergic and cardiovascular effects. This safety and tolerability profile, combined with proven efficacy, makes SSRIs the first-line pharmacologic choice for most patients with major depressive disorder according to current treatment guidelines. Common agents in this class include fluoxetine, sertraline, escitalopram, and paroxetine.

• A. Tricyclic antidepressants block reuptake of both serotonin and norepinephrine and have significant anticholinergic effects; they are not the agent described and are not first-line.
• B. Monoamine oxidase inhibitors act by inhibiting the enzyme that degrades monoamines, not by blocking reuptake transporters, and carry dietary restrictions.
• D. SNRIs block reuptake of both serotonin and norepinephrine, not a single selective transporter, and are not specifically described here.

This patient has serotonin syndrome, precipitated by combining an SSRI (fluoxetine) with tramadol, which also inhibits serotonin reuptake and has mu-opioid activity. The classic triad is autonomic instability (hyperthermia, tachycardia, hypertension, diaphoresis), neuromuscular abnormalities (tremor, hyperreflexia, clonus, rigidity that is typically more pronounced in the lower limbs), and altered mental status (agitation, confusion). Onset is rapid, usually within 24 hours of the precipitating combination, distinguishing it from neuroleptic malignant syndrome, which develops over days with hyporeflexia. Management includes stopping the offending agents, supportive cooling, benzodiazepines, and cyproheptadine in severe cases.

• A. Hyporeflexia and gradual onset after antipsychotic use describes neuroleptic malignant syndrome, not serotonin syndrome.
• B. Serotonin syndrome always involves neuromuscular and mental status changes along with autonomic findings, not an isolated autonomic picture.
• C. Isolated extrapyramidal rigidity without systemic features is typical of drug-induced parkinsonism, not serotonin syndrome.

Tricyclic antidepressants block cardiac fast sodium channels, causing QRS widening and risk of ventricular arrhythmias; a QRS greater than 100 milliseconds signals significant cardiotoxicity. Intravenous sodium bicarbonate increases extracellular pH and sodium concentration, which reverses sodium channel blockade and narrows the QRS, and is the cornerstone treatment for TCA-induced cardiotoxicity along with cardiac monitoring. Target is to maintain serum pH around 7.5 to 7.55. Physostigmine is contraindicated because it can worsen cardiac conduction and precipitate seizures or arrhythmias in TCA overdose.

• A. Physostigmine is contraindicated in TCA overdose as it can worsen cardiotoxicity and precipitate seizures.
• C. Flumazenil reverses benzodiazepine overdose and is not indicated here; it can also precipitate seizures in mixed overdoses.
• D. Activated charcoal alone is insufficient when there is already evidence of cardiotoxicity requiring active reversal with bicarbonate.

Monoamine oxidase in the gut and liver normally degrades dietary tyramine, an indirect sympathomimetic amine found in aged cheeses, cured meats, and fermented beverages. MAOIs like phenelzine block this first-pass metabolism, allowing tyramine to enter the circulation, enter sympathetic nerve terminals, and trigger massive release of stored norepinephrine, producing a hypertensive crisis with headache, palpitations, and diaphoresis. This is why patients on MAOIs are counseled to follow a low-tyramine diet. Treatment of the crisis includes alpha-blockers such as phentolamine.

• A. The hypertensive crisis is due to catecholamine excess, not a primary renal sodium effect.
• B. Tyramine does not act through cytochrome P450 enzyme inhibition; the interaction is pharmacodynamic via catecholamine release.
• D. Tyramine acts indirectly through catecholamine release, not by direct serotonin receptor stimulation.

Duloxetine is a serotonin-norepinephrine reuptake inhibitor that is approved for both major depressive disorder and diabetic peripheral neuropathic pain. Its combined enhancement of serotonergic and noradrenergic descending inhibitory pathways in the spinal cord reduces neuropathic pain signaling while also treating depressive symptoms, making it a rational single-agent choice in this patient with overlapping conditions. Other SNRIs like venlafaxine also have some evidence in neuropathic pain, but duloxetine has the strongest indication and guideline support for this combination.

• A. Mirtazapine is useful for depression with insomnia or poor appetite but is not indicated for neuropathic pain.
• C. Bupropion, an NDRI, treats depression and aids smoking cessation but has no proven role in neuropathic pain.
• D. Fluoxetine, a pure SSRI, has no established efficacy for neuropathic pain.

According to DSM-5 criteria, a manic episode requires a distinct period of abnormally and persistently elevated, expansive, or irritable mood and abnormally and persistently increased activity or energy, lasting at least 1 week (or any duration if hospitalization is necessary), present most of the day, nearly every day. During this period, at least three (or four if mood is only irritable) additional symptoms must be present, such as decreased need for sleep, pressured speech, grandiosity, and risky or impulsive behavior, causing marked impairment in functioning. This patient's 8-day history of elevated energy, decreased sleep need, grandiosity, and impulsive spending with irritability and functional impairment meets full criteria for mania, not hypomania, which requires only 4 days and lacks marked impairment.

• B. Psychotic features are not required for diagnosis of mania, and the duration criterion of 1 month is incorrect.
• C. A 2-week duration with neurovegetative symptoms describes the criteria for a major depressive episode, not mania.
• D. A 4-day duration without significant functional impairment describes a hypomanic episode, not a full manic episode.

Lithium's mood-stabilizing effect is attributed to inhibition of inositol monophosphatase and inositol polyphosphate 1-phosphatase, which depletes free inositol and dampens phosphoinositide-mediated signal transduction, and it also inhibits glycogen synthase kinase-3β. Its therapeutic index is narrow (therapeutic range 0.6-1.2 mEq/L for maintenance), so serum levels must be checked regularly, typically 12 hours after the last dose. Valproate, carbamazepine, and lamotrigine act mainly through sodium channel blockade or GABA modulation and do not require this specific inositol-depletion monitoring rationale.

• B. Lamotrigine blocks sodium channels and reduces glutamate release; it is not linked to inositol monophosphatase inhibition.
• C. Carbamazepine blocks voltage-gated sodium channels; it does not act via inositol depletion.
• D. Valproate increases GABA activity and blocks sodium channels, not inositol monophosphatase.

Thiazide diuretics cause natriuresis, which leads to volume contraction and a compensatory increase in proximal tubular sodium and lithium reabsorption, raising serum lithium levels and precipitating toxicity. Early signs of lithium toxicity include coarse tremor, nausea, and diarrhea, progressing to ataxia, dysarthria, confusion, and seizures as levels rise above 2.0 mEq/L. Lithium is not protein-bound and is not hepatically metabolized, so those mechanisms are irrelevant. NSAIDs and dehydration similarly precipitate toxicity by reducing renal lithium clearance.

• A. Lithium is excreted almost entirely unchanged by the kidneys and undergoes negligible hepatic metabolism.
• B. Lithium circulates largely unbound to plasma proteins, so displacement is not a mechanism.
• C. Thiazides do not cause direct tubular necrosis; the risk here is pharmacokinetic, not toxic injury.

Chronic lithium use causes nephrogenic diabetes insipidus by downregulating aquaporin-2 water channels in the renal collecting duct principal cells, making them unresponsive to antidiuretic hormone (ADH); hence desmopressin fails to concentrate the urine. This is distinct from central diabetes insipidus, where ADH secretion itself is deficient and desmopressin corrects the urine osmolality. Lithium can also cause hypothyroidism by inhibiting thyroid hormone release and iodine uptake, so thyroid function should be monitored alongside renal function in long-term lithium users. Management of lithium-induced nephrogenic DI includes amiloride, which blocks lithium entry into collecting duct cells.

• A. Lithium does not cause autoimmune destruction of the pituitary; ADH secretion remains intact.
• B. Lithium does not destroy hypothalamic osmoreceptors; the defect is renal, at the level of the collecting duct.
• D. ADH secretion is preserved or even increased as a compensatory response; the renal tubule fails to respond to it.

First-trimester lithium exposure is associated with Ebstein anomaly, a congenital heart defect involving apical displacement of the tricuspid valve, though the absolute risk is low. Valproate is strongly teratogenic and causes neural tube defects such as spina bifida due to interference with folate metabolism, along with characteristic facial dysmorphism and reduced IQ in exposed children. Because of this risk, valproate is generally avoided in women of childbearing age, and folic acid supplementation is advised if it must be used. Lithium carries a lower but still notable cardiac teratogenic risk, warranting fetal echocardiography if used in pregnancy.

• B. This reverses the classic drug-anomaly associations; lithium causes Ebstein anomaly, not neural tube defects.
• C. Cleft palate and limb reduction defects are not the characteristic anomalies linked to these drugs.
• D. Renal agenesis and craniofacial defects are not the classic teratogenic associations of lithium and valproate.

Generalized anxiety disorder requires excessive, difficult-to-control anxiety and worry about multiple events or activities, present more days than not, for a minimum duration of 6 months, along with at least three associated symptoms such as restlessness, fatigue, difficulty concentrating, irritability, muscle tension, or sleep disturbance. This chronicity criterion distinguishes GAD from acute stress reactions or adjustment disorders, which have shorter required durations. The worry in GAD is diffuse and not confined to discrete attacks or specific objects, unlike panic disorder or specific phobia. Treatment typically involves SSRIs or SNRIs along with cognitive behavioral therapy.

• B. Three months is not the standard diagnostic threshold for GAD, which requires six months.
• C. Two weeks is the duration criterion used for major depressive episodes, not GAD.
• D. One month is too short and corresponds more closely to acute stress-type presentations, not GAD.

Panic disorder is characterized by recurrent, unexpected panic attacks, discrete episodes of intense fear peaking within minutes with symptoms like palpitations, sweating, and fear of dying, followed by at least one month of persistent anticipatory anxiety about recurrence or behavioral changes to avoid attacks. This patient's sudden, self-limited episodes with interictal anticipatory anxiety and avoidance behavior are classic for panic disorder, and the situational avoidance here reflects emerging agoraphobic features rather than a primary phobia. GAD involves chronic, diffuse worry without discrete attacks, social anxiety disorder is triggered specifically by social or performance situations, and OCD involves intrusive thoughts with compulsive rituals, none of which fit this episodic pattern.

• A. OCD is characterized by intrusive obsessions and compulsions, not discrete panic attacks with anticipatory anxiety.
• B. Social anxiety disorder involves fear specifically tied to social or performance situations, not spontaneous attacks anywhere.
• D. GAD presents with chronic, pervasive worry rather than discrete, sudden panic episodes.

Benzodiazepines bind to a specific site on the GABA-A receptor complex, distinct from the GABA binding site, and increase the frequency of chloride channel opening in response to GABA. This enhances chloride influx, causing neuronal hyperpolarization and decreased excitability, which produces the anxiolytic, sedative, muscle relaxant, and anticonvulsant effects of this drug class. Unlike barbiturates, which increase the duration of channel opening, benzodiazepines increase the frequency of opening and require the presence of GABA to act, making them safer in overdose. This mechanism underlies their rapid onset of anxiolytic action.

• A. NMDA receptors are glutamate-gated and mediate excitatory neurotransmission, not the target of benzodiazepines.
• B. 5-HT2A receptors are targets of atypical antipsychotics and some antidepressants, not benzodiazepines.
• D. Voltage-gated sodium channels are blocked by drugs like phenytoin and local anesthetics, not benzodiazepines.

Flumazenil is a competitive GABA-A receptor antagonist used to reverse benzodiazepine-induced sedation and respiratory depression. In patients with chronic benzodiazepine use or co-ingestion of pro-convulsant drugs such as tricyclic antidepressants, abrupt reversal of GABAergic inhibition can precipitate withdrawal seizures or status epilepticus. Because of this risk, flumazenil is used cautiously and is generally avoided in patients with long-term benzodiazepine dependence or unknown co-ingestants. It has a short half-life, so resedation can also occur, requiring close monitoring after administration.

• A. Flumazenil is not nephrotoxic and does not cause renal failure.
• B. Malignant hyperthermia is linked to volatile anesthetics and succinylcholine, not flumazenil.
• C. Flumazenil is not associated with hepatotoxicity.

This patient has obsessive-compulsive disorder, with contamination obsessions (intrusive thoughts) driving washing and checking compulsions (repetitive behaviours performed to reduce distress). First-line pharmacotherapy is a selective serotonin reuptake inhibitor such as fluoxetine, but OCD typically requires higher doses than those used for depression, along with a longer trial period of 8-12 weeks before assessing response. Clomipramine, a tricyclic with potent serotonergic activity, is an alternative when SSRIs fail. Cognitive behavioural therapy with exposure and response prevention is used alongside medication.

• B. Propranolol is used for performance anxiety and tremor, not for OCD.
• C. Benzodiazepines like alprazolam are not first-line and do not target the core obsessive-compulsive symptoms.
• D. Antipsychotics are used as augmentation in treatment-resistant OCD, not as first-line monotherapy.

Alcohol withdrawal follows a predictable timeline: tremors and autonomic hyperactivity begin around 6-12 hours, withdrawal seizures peak at 24-48 hours, and delirium tremens classically develops at 48-96 hours after the last drink. Delirium tremens is characterized by confusion, disorientation, agitation, vivid hallucinations (often tactile, such as formication with crawling insects), and marked autonomic instability with tachycardia, hypertension, fever, and diaphoresis. It is a medical emergency with significant mortality if untreated and requires aggressive benzodiazepine therapy and supportive care. The timeline and clinical picture at 70 hours in this patient are classic for this complication.

• A. Alcoholic hallucinosis presents with hallucinations but without the global confusion, disorientation, and severe autonomic instability of delirium tremens.
• B. Simple withdrawal tremor occurs early (6-12 hours) and lacks the confusion, hallucinations, and severe autonomic instability seen here.
• C. Wernicke encephalopathy presents with ophthalmoplegia, ataxia, and confusion due to thiamine deficiency, not this autonomic and hallucinatory picture.

In chronic alcoholics, glucose administration without prior thiamine replacement can precipitate or worsen Wernicke encephalopathy by rapidly consuming the limited thiamine reserves needed as a cofactor for carbohydrate metabolism. Therefore, thiamine should always be given before or together with dextrose in alcohol-dependent or malnourished patients presenting with hypoglycemia. Alcohol withdrawal itself is managed with benzodiazepines, most commonly a tapering regimen of diazepam or chlordiazepoxide, which also covers seizure risk. Magnesium correction, if needed, is supportive but does not take priority over thiamine before glucose.

• A. Magnesium sulfate may be given if hypomagnesemia is confirmed but is not the mandatory step before glucose administration.
• C. Phenytoin is not effective for alcohol withdrawal seizures; benzodiazepines are the treatment of choice, and this is not the immediate priority before dextrose.
• D. Liver function tests are useful for assessment but are not an emergent intervention needed before dextrose.

Chronic alcohol use impairs intestinal absorption and hepatic storage of thiamine, and thiamine is a cofactor for transketolase and other enzymes needed for cerebral glucose metabolism. Deficiency causes selective neuronal damage in the mammillary bodies, thalamus, and periaqueductal gray matter, producing the Wernicke triad of ophthalmoplegia, ataxia, and confusion. If untreated, irreversible damage to the mammillary bodies and dorsomedial thalamus leads to Korsakoff amnesia with confabulation. Prompt parenteral thiamine before glucose administration is essential to prevent progression.

• A. B12 deficiency causes subacute combined degeneration and megaloblastic anemia, not this picture.
• B. Pyridoxine deficiency causes peripheral neuropathy and sideroblastic anemia, not this triad.
• C. Niacin deficiency causes pellagra with dermatitis, diarrhea, and dementia.

Disulfiram irreversibly inhibits aldehyde dehydrogenase, the enzyme that normally converts acetaldehyde to acetic acid in ethanol metabolism. When alcohol is consumed, acetaldehyde accumulates in the blood, producing the unpleasant disulfiram-alcohol reaction of flushing, headache, nausea, vomiting, and tachycardia. This aversive reaction is used therapeutically to reinforce abstinence in motivated patients with alcohol use disorder. Patients must be warned to avoid hidden sources of alcohol such as mouthwash and cough syrups.

• A. Alcohol dehydrogenase converts ethanol to acetaldehyde and is not the target; inhibiting it would reduce acetaldehyde buildup, not increase it.
• C. Monoamine oxidase inhibition is relevant to tyramine reactions with MAOIs, not the alcohol flush reaction.
• D. CYP2E1 contributes a minor pathway of ethanol oxidation but is not the site of disulfiram action.

The combination of pinpoint pupils, severe respiratory depression, and depressed consciousness strongly suggests opioid overdose, which is a clinical emergency requiring immediate reversal of respiratory depression. Naloxone is a competitive mu-opioid receptor antagonist that rapidly reverses opioid-induced respiratory depression and sedation, often within 2-3 minutes of administration. It can be given intravenously, intramuscularly, or intranasally and repeated as needed because its duration of action is shorter than that of many opioids. Airway support and oxygenation accompany naloxone administration but should not delay its use.

• B. Flumazenil reverses benzodiazepine, not opioid, toxicity and risks seizures in mixed overdoses.
• C. Securing the airway is supportive but delaying the specific antidote in a reversible, rapidly acting emergency is not optimal.
• D. Sodium bicarbonate has no role in opioid overdose; it is used for conditions like tricyclic antidepressant toxicity or severe metabolic acidosis.

Autism spectrum disorder is diagnosed based on two core symptom domains: persistent deficits in social communication and social interaction, and restricted, repetitive patterns of behavior, interests, or activities. This child shows both domains: lack of eye contact, absent joint attention (pointing to share interest), and no pretend play represent social communication deficits, while insistence on sameness and stereotyped hand flapping represent restricted, repetitive behavior. Both domains must be present from early developmental periods and cause functional impairment for the diagnosis, per DSM-5 criteria. Early identification allows timely behavioral and developmental interventions.

• A. Selective mutism is a distinct anxiety-related disorder characterized by failure to speak in specific social situations despite speaking elsewhere.
• B. Regression in language with preserved motor milestones is not a defining diagnostic domain and does not describe this child's findings.
• D. Inattention and hyperactivity-impulsivity define ADHD, not autism spectrum disorder.

Methylphenidate inhibits the dopamine and norepinephrine reuptake transporters, increasing catecholamine levels in the synaptic cleft, particularly in the prefrontal cortex, which improves attention and impulse control. Its most common adverse effects are appetite suppression and insomnia, and with long-term use, mild growth delay in height and weight can occur, requiring periodic monitoring of growth parameters. Hepatotoxicity, agranulocytosis, and extrapyramidal symptoms are not characteristic adverse effects of stimulant medications. Drug holidays are sometimes used to minimize growth suppression.

• A. Methylphenidate is not a known hepatotoxin.
• B. Extrapyramidal symptoms occur with dopamine-blocking antipsychotics, not stimulants that increase catecholamines.
• D. Agranulocytosis is associated with drugs like clozapine, not stimulants.

Delirium is characterized by an acute onset, a fluctuating course over hours to days, and a core deficit in attention and awareness, often with a clear precipitating medical cause. Dementia, in contrast, has an insidious onset with a slowly progressive, relatively stable course and attention is usually preserved until late stages. Visual hallucinations and disorientation can occur in both conditions and are therefore not distinguishing features. The abrupt change in this patient's mental status with fluctuation and attentional impairment on a background of stable chronic cognitive decline points to superimposed delirium.

• B. Progressive memory loss over months to years describes the chronic dementia, not the acute change being assessed.
• C. Visual hallucinations can occur in both delirium and some dementias such as dementia with Lewy bodies, so this is not distinguishing.
• D. Disorientation to time and place can occur in both delirium and dementia and does not distinguish between them.

The Mini-Mental State Examination is a widely used 30-point bedside screening tool for cognitive impairment, assessing orientation, registration, attention and calculation, recall, and language. A score of 24-30 is generally considered normal, 18-23 indicates mild cognitive impairment, and a score below 18 indicates moderate to severe impairment. A score of 20 therefore falls in the mild cognitive impairment range, consistent with early dementia, and should prompt further diagnostic workup rather than reassurance. The MMSE is a screening tool and does not by itself establish a diagnosis of dementia.

• B. Normal cognition on the MMSE is reflected by a score of 24-30, higher than this patient's score.
• C. Severe cognitive impairment corresponds to much lower scores, typically below 10.
• D. Delirium is a clinical diagnosis based on acute fluctuating attention deficits, not defined by a fixed MMSE score.

Alzheimer's disease is associated with degeneration of cholinergic neurons in the nucleus basalis of Meynert in the basal forebrain, leading to reduced acetylcholine levels in the cortex and hippocampus, which correlates with memory impairment. Donepezil and rivastigmine are acetylcholinesterase inhibitors that block the breakdown of acetylcholine, increasing its availability at the synapse and providing modest symptomatic improvement in cognition. Rivastigmine additionally inhibits butyrylcholinesterase. These drugs do not alter the underlying amyloid or tau pathology but can temporarily improve symptoms.

• A. Serotonergic dysfunction is more relevant to mood disorders than to the primary cognitive deficit mechanism of Alzheimer's disease.
• B. The dopaminergic system is primarily implicated in Parkinson's disease, not the core cholinergic deficit of Alzheimer's disease.
• C. GABAergic dysfunction is not the primary mechanism targeted by standard Alzheimer's pharmacotherapy.

Cluster A personality disorders include paranoid, schizoid, and schizotypal types, characterized by odd or eccentric thinking and social withdrawal. Cluster B includes antisocial, borderline, histrionic, and narcissistic types, characterized by dramatic, emotional, or erratic behavior and impulsivity. Cluster C includes avoidant, dependent, and obsessive-compulsive types, characterized by anxious or fearful behavior. This classification helps organize the ten personality disorder diagnoses by shared clinical features for teaching and clinical recognition.

• A. This option places avoidant in Cluster B and histrionic in Cluster C, which is reversed.
• B. This option places avoidant and histrionic in the wrong clusters relative to schizoid.
• D. This option swaps histrionic and schizoid between the wrong clusters.

Borderline personality disorder is characterized by a pervasive pattern of instability in relationships, self-image, and affect, along with marked impulsivity, beginning by early adulthood. A core defense mechanism seen in this disorder is splitting, in which the patient views others as either all good or all bad, leading to the idealize-devalue cycle described. Chronic emptiness, fear of abandonment, identity disturbance, and recurrent self-harm in response to perceived rejection are classic diagnostic features. While histrionic and narcissistic traits can overlap, the specific combination of splitting, self-harm, and abandonment-triggered instability is most typical of borderline personality disorder.

• A. Dependent personality disorder features submissiveness and need to be taken care of rather than the alternating idealization-devaluation pattern described.
• C. Narcissistic personality disorder features grandiosity and need for admiration rather than the fear of abandonment and self-harm seen here.
• D. Histrionic personality disorder features excessive emotionality and attention-seeking but not the characteristic splitting and self-harm pattern described.

Factitious disorder involves the conscious and intentional fabrication or induction of symptoms, but the motivation is internal psychological gain, such as assuming the sick role and receiving medical attention, rather than any external reward. This distinguishes it from malingering, where symptoms are also consciously produced but for a clear external incentive like financial compensation, disability benefits, or avoiding legal or work obligations. Somatic symptom disorder differs from both in that symptom production is not intentional; the patient genuinely experiences and worries excessively about physical symptoms without consciously faking them. The repeated hospital-seeking behavior with willingness to undergo invasive procedures purely to maintain the patient role is classic for factitious disorder.

• B. This describes somatic symptom disorder, where production is unconscious and distress is genuine, not matching this patient's intentional fabrication.
• C. This describes malingering, which requires an external incentive, absent in this vignette.
• D. This describes a conversion-type mechanism with involuntary symptoms, not the deliberate fabrication seen here.

Conversion disorder (functional neurological symptom disorder) presents with a neurological deficit that is incompatible with recognized neurological disease, follows a psychologically stressful event, and is not intentionally produced. Clues here include the temporal link to an emotionally traumatic event, normal reflexes and imaging, inconsistency on examination (movement when distracted), and la belle indifference. The symptom is not consciously feigned for external gain, which distinguishes it from malingering.

• A. Guillain-Barre syndrome would show absent or reduced reflexes, elevated CSF protein, and abnormal nerve conduction studies.
• B. Malingering involves conscious, intentional production of symptoms for an external gain such as financial compensation or avoiding duty, which is not evident here.
• D. Somatic symptom disorder involves excessive distress and preoccupation about physical symptoms rather than an acute neurological deficit incompatible with disease.

This patient has severe depression with psychotic features (nihilistic delusion of being dead - Cotard syndrome) and life-threatening food and fluid refusal causing dehydration and electrolyte imbalance. ECT is indicated as a first-line, rapid-acting treatment when there is high suicide risk, psychotic features, catatonia, or refusal of food/fluids threatening life, because it works faster than oral pharmacotherapy and does not depend on patient cooperation with oral intake. Delaying treatment for oral medication trials would risk further physical deterioration.

• A. Cognitive behavioral therapy is a slow-acting psychotherapy, not appropriate for an acute life-threatening presentation.
• C. Oral antipsychotic-antidepressant combination takes weeks to act and is unreliable in a patient refusing oral intake and at imminent physical risk.
• D. Antifungal therapy is irrelevant; nutritional support alone does not address the underlying life-threatening psychiatric emergency.

Succinylcholine, used during ECT to produce muscle relaxation and prevent fracture/injury during the seizure, is normally metabolized rapidly by plasma pseudocholinesterase (butyrylcholinesterase). Patients with congenital or acquired pseudocholinesterase deficiency cannot break down succinylcholine efficiently, leading to prolonged neuromuscular blockade manifesting as extended apnea and muscle pain from sustained depolarization. Management involves continued ventilatory support until the drug effect wears off. This is distinct from the memory disturbances that are also recognized adverse effects of ECT itself.

• B. Retrograde amnesia is a cognitive adverse effect of ECT itself and does not explain prolonged apnea or muscle pain.
• C. Status epilepticus would present with prolonged or repeated seizure activity, not muscle pain and apnea.
• D. Malignant hyperthermia presents with hyperthermia, muscle rigidity, and hypercapnia, not isolated prolonged apnea after succinylcholine.

The Mental Healthcare Act 2017 recognizes the autonomy of persons with mental illness by allowing them to make an advance directive specifying how they wish to be treated or not treated, and who their nominated representative shall be, in the event of future mental illness. This directive must generally be followed by the treating team unless it does not apply to the current situation or is deemed to adversely affect the person, in which case the Mental Health Review Board can be approached to review or alter it. It must be registered with the Board to be valid.

• B. An advance directive remains valid as registered until revoked, altered, or cancelled; it does not automatically expire with each admission.
• C. A judicial magistrate's countersignature at the time of treatment is not required; registration is with the Mental Health Review Board.
• D. An advance directive is made by the person with mental illness themselves while they have the capacity to do so, not by family members on their behalf.

Typical antipsychotics act primarily by blocking dopamine D2 receptors. In the mesolimbic pathway this reduces positive psychotic symptoms, but blockade in the nigrostriatal pathway disrupts normal dopaminergic inhibition of striatal cholinergic neurons, producing extrapyramidal symptoms such as parkinsonism, dystonia, and akathisia. The degree of D2 blockade correlates with both antipsychotic efficacy and EPS risk. Atypical antipsychotics cause fewer EPS because of additional 5-HT2A antagonism and faster D2 dissociation.

• A. M1 blockade causes anticholinergic effects like dry mouth and constipation, not parkinsonism.
• B. 5-HT2A blockade modulates dopamine release and is linked to atypical antipsychotics causing fewer EPS, not the cause here.
• D. H1 blockade causes sedation and weight gain, not extrapyramidal symptoms.

Clozapine is reserved for treatment-resistant schizophrenia because of its risk of life-threatening agranulocytosis, occurring in about 1% of patients, usually within the first 18 weeks. Mandatory baseline and periodic absolute neutrophil count monitoring (weekly for the first 18 weeks, then less frequently) is required under clozapine risk management protocols to detect agranulocytosis early and allow prompt discontinuation. Fasting lipids and ECG are useful for monitoring metabolic and cardiac effects but are not the mandatory safety parameter defining clozapine use. Prolactin elevation is not a significant clozapine effect.

• A. Lipid profile monitoring is recommended for metabolic risk but is not the mandatory hematologic safety requirement.
• B. Clozapine characteristically causes minimal or no prolactin elevation, unlike risperidone or haloperidol.
• C. ECG is useful to screen for myocarditis/QT prolongation but is not the defining mandatory monitoring test for clozapine.

Neuroleptic malignant syndrome results from dopamine blockade causing severe muscle rigidity, hyperthermia, autonomic instability, and altered consciousness, with markedly elevated CK from muscle breakdown. Dantrolene, a direct skeletal muscle relaxant that inhibits calcium release from the sarcoplasmic reticulum via the ryanodine receptor, reduces rigidity and hypermetabolism. Bromocriptine, a dopamine agonist, is used adjunctively to reverse central dopamine blockade. Supportive care with cooling, hydration, and stopping the offending drug is essential alongside these agents.

• B. Levodopa is not used in NMS management; bromocriptine (a dopamine agonist) is preferred, not levodopa.
• C. Propranolol may help autonomic symptoms but does not address the core rigidity-hyperthermia mechanism.
• D. Diazepam provides sedation and some muscle relaxation but is not the specific agent targeting the hypermetabolic rigidity of NMS.

Acute dystonia typically occurs within hours to a few days of starting or increasing an antipsychotic, presenting with sudden sustained muscle contractions such as torticollis, oculogyric crisis, or laryngospasm. It is more common in young men and with high-potency typical antipsychotics. It responds rapidly to intravenous or intramuscular anticholinergics or antihistamines. In contrast, akathisia develops over days to weeks, parkinsonism over weeks, and tardive dyskinesia only after months to years of therapy.

• A. Akathisia presents as subjective restlessness and inability to sit still, developing over days to weeks, not hours.
• B. Tardive dyskinesia appears after months to years of antipsychotic exposure, with orofacial dyskinetic movements, not within hours.
• D. Drug-induced parkinsonism develops over weeks with bradykinesia, rigidity, and tremor, not acute dystonic posturing.

Among atypical antipsychotics, clozapine and olanzapine carry the highest risk of weight gain, dyslipidemia, and new-onset type 2 diabetes mellitus, attributed largely to strong antagonism at histamine H1 and serotonin 5-HT2C receptors affecting appetite regulation. Regular monitoring of weight, waist circumference, fasting glucose, and lipid profile is recommended during treatment with these agents. Aripiprazole, ziprasidone, and lurasidone are considered metabolically more neutral atypical agents with comparatively lower risk of weight gain.

• A. Aripiprazole is a partial D2 agonist with one of the lowest metabolic risk profiles among atypicals.
• C. Lurasidone has a relatively favorable metabolic profile with minimal weight gain among atypical antipsychotics.
• D. Ziprasidone is metabolically weight-neutral and has low risk of significant weight gain.

Dopamine normally acts as the principal inhibitory regulator of prolactin secretion from anterior pituitary lactotroph cells via the tuberoinfundibular pathway. Antipsychotics that strongly block D2 receptors in this pathway, such as risperidone and haloperidol, remove this inhibitory tone and cause hyperprolactinemia, presenting clinically as galactorrhea, amenorrhea, and sexual dysfunction. Risperidone causes disproportionately high prolactin elevation because it poorly penetrates the blood-brain barrier at the pituitary level, allowing greater peripheral D2 blockade. Drugs sparing this pathway, like aripiprazole and quetiapine, cause minimal prolactin elevation.

• A. Mesolimbic pathway blockade is responsible for antipsychotic efficacy against positive psychotic symptoms, not prolactin changes.
• C. Nigrostriatal pathway blockade causes extrapyramidal symptoms such as parkinsonism and dystonia, not prolactin elevation.
• D. Mesocortical pathway blockade is implicated in worsening of negative symptoms and cognitive effects, not hyperprolactinemia.

Fluphenazine decanoate is a long-acting depot formulation in which the drug is esterified with decanoic acid and dissolved in an oily vehicle for intramuscular injection, allowing slow release over 2-4 weeks and ensuring sustained antipsychotic effect in patients with poor treatment adherence. Depot preparations are particularly useful in patients with repeated relapses due to non-adherence, as they remove dependence on daily pill-taking. Other examples include risperidone long-acting microspheres and paliperidone palmitate. Oral and sublingual formulations require daily dosing and do not address adherence problems in the same way.

• A. Oral aripiprazole requires daily intake and is not a long-acting injectable.
• B. Sublingual asenapine is a rapidly absorbed short-acting formulation, not a depot preparation.
• D. Oral olanzapine requires daily dosing and does not solve the adherence problem described.