How we assess intelligence in psychiatry
Simply measuring IQ is not enough: this indicator does not show why a patient is struggling with a task. For accurate diagnosis, physicians use the approach of Karl Jaspers, who divided intelligence into three components:
- Prerequisites of intelligence: memory, attention, consciousness. If these are impaired (e.g., in delirium or depression), a person may temporarily appear helpless, but intelligence itself may remain high.
- Knowledge base: reflects living conditions, education, and upbringing, rather than the essence of reason itself.
- Intelligence proper: the ability to find connections between phenomena and think abstractly. It is this parameter that is impaired in mental retardation.
Normally, thinking evolves from sensori-motor (reaching for a toy) to concrete-imaginative, and then to abstract (operating with concepts that cannot be touched). In oligophrenia, development halts, and abstract thinking fails to develop.
Clinical presentation
Underdevelopment in mental retardation affects absolutely all spheres of the psyche, but is most prominent in cognitive functions.
- Thinking and cognition: patients fail to grasp the hidden meaning of events and cannot transfer past experience to new situations. They are only capable of copying actions and following simple work algorithms.
- Speech: extremely poor, abundant in verbal clichés and agrammatisms (oligophasia). Speech defects (slurring) are common.
- Emotional sphere: higher feelings (conscience, empathy, morality) remain undifferentiated. Reactions are primitive and immediate, making even adult patients resemble children.
- Somatic status: microcephaly, eye and ear anomalies, and neurological defects (clumsiness, epileptiform seizures) are frequently detected.
Causes of mental retardation
Oligophrenia is a clinically heterogeneous group. More than 40% of cases remain of unknown etiology. Known causes are divided into two groups:
- Hereditary factors: hundreds of syndromes are described (including Down syndrome, phenylketonuria). Interestingly, severe genetic forms often occur in children born to healthy parents, whereas mild degrees are more frequently inherited.
- Exogenous influences: can act during pregnancy (alcohol, rubella, syphilis, toxicoses, teratogenic drugs in the first trimester), during labor ( precipitous labor, asphyxia, trauma), or in the child's first years of life (neuroinfections, severe debilitating illnesses).
Dynamics and decompensation
A crucial postulate: oligophrenia is not a progressive disease. It is a pathological state representing the outcome of prior brain damage.
In general, mental retardation is characterized by positive (evolutionary) dynamics. As they grow older, individuals accumulate skills and adapt better within a specially created environment.
Decompensations may occur under the influence of stress, hormonal storms (especially during puberty), or infections. They manifest as moodiness, psychopathy-like behavior (running away, aggression), or even atypical, primitive psychoses with minor delusional ideas. Following the resolution of such episodes, the patient's condition returns to its baseline level.
Briefly: answers to topical questions
What degrees of mental retardation are distinguished in traditional psychiatry and ICD-10?
ICD-10 distinguishes four degrees of mental retardation: mild (F70), moderate (F71), severe (F72), and profound. The traditional Russian classification uses three terms: debility, imbecility, and idiocy.
What is the fundamental difference between oligophrenia and dementia?
Oligophrenia is a non-progressive mental underdevelopment arising during the period of intellectual formation, with predominant insufficiency of intellectual capacities. Dementia is an acquired mental defect with primary impairment of intellectual functions, loss of previously acquired knowledge and abilities, a general decline in mental productivity, and personality changes.
| Sign | Oligophrenia | Dementia |
|---|---|---|
| Essence | Underdevelopment of mental functions, predominantly intelligence | Acquired defect and loss of previously formed knowledge and abilities |
| Dynamics | Non-progressive nature; evolutionary changes and decompensations are possible | Depends on etiology: progressive worsening of the defect or a stable course with potential partial recovery of functions in the first few months for certain causes |
What hereditary syndromes and metabolic disorders lead to mental retardation?
The following hereditary syndromes and metabolic disorders lead to mental retardation:
- Down syndrome — trisomy of chromosome 21.
- Fragile X syndrome (Fragile X Syndrome) — fragile X chromosome syndrome.
- Phenylketonuria — hereditary enzymopathy associated with impaired amino acid metabolism due to a deficiency of phenylalanine hydroxylase.
- Gargoylism — accompanied by connective tissue defects, bone and joint malformations.
- Marfan syndrome — characterized by tall stature, asthenic build, long limbs, and joint hypermobility.
- Homocystinuria — accompanied by heart defects, spastic paralysis, and thrombosis.
- Galactosemia — hereditary enzymopathy with hepatomegaly, cataracts, and ovarian dysfunction.
- Bardet-Biedl syndrome — manifests with retinitis pigmentosa, obesity, and hypogenitalism.
- Progeria — accompanied by premature aging.
Mental retardation is not a "disease," but a "scar." To distinguish it from dementia, remember the age threshold of 3 years. If the brain is damaged before age 3, the foundation was never built (oligophrenia). If after, the finished building is destroyed (dementia).
Class and exam questions
Why cannot standard adult IQ tests be used?
The classic IQ calculation formula (mental age / chronological age) only works for children as it reflects the rate of development. In adults over 15, intellectual dynamics are different, so special tests are used, such as the Wechsler Adult Intelligence Scale.
How to quickly test abstract thinking during an appointment?
Ask the patient to explain the meaning of a proverb or find differences between similar concepts (e.g., "lie and mistake"). You should not ask rote-learned facts like the multiplication table—patients with severe defects may answer them mechanically.
Can a person with oligophrenia develop schizophrenia?
Yes, psychoses occur in oligophrenia, although their status is debatable. Symptoms in such cases are extremely primitive, stereotyped, and often lack a coherent system, which complicates the classical diagnosis of schizophrenia.
What else to study on this topic
- Diagnostic criteria according to G.E. Sukhareva (detailed review).
- Symptomatology of atypical psychoses in the context of oligophrenia (minor delusions, reduced delirium).
- Historical approaches to classification (erethic and torpid forms according to Kraepelin).
- Differential diagnosis with mental retardation (developmental delay).
- Neuroimaging (CT/MRI) and EEG findings in various degrees of mental retardation.
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