Classification of Mental Disorders

Difficulties of systematics and its significance

The classification of mental disorders is traditionally considered one of the most complex and debatable areas in medicine. The reasons for discrepancies between different countries and psychiatric schools lie in the specifics of the discipline itself. First, there is still a shortage of absolutely reliable, objective diagnostic methods. Second, knowledge about the etiology (causes) and pathogenesis (mechanisms of development) of many disorders remains insufficient.

Nevertheless, a reliable classification is vitally necessary in two global spheres:

• Practical medicine: for developing effective treatment regimens, planning prevention, maintenance therapy, and rehabilitation measures.
• Social and legal sphere: for organizing social welfare, conducting expert evaluations (including during military conscription), and resolving legal disputes where strict unification of patient status assessment is required.

Syndromological (phenomenological) principle

Historically, the syndromological approach was the first, implying the identification of the leading disorder (syndrome) at a given point in time. Until the late 19th century, it dominated psychiatry. Its theoretical basis was the single psychosis theory, which assumed that there is only one mental illness, and different symptoms in different people are simply different stages of development of this single pathology.

The entire organization of care and management of patients was built on the basis of the leading syndrome:

1. Depressive syndrome dictated the need for strict supervision to prevent suicide attempts.
2. Catatonic syndrome indicated problems with food intake, often requiring tube feeding.
3. Mild neurotic-level disorders indicated the possibility of outpatient management.

In the 20th century, this approach regained immense relevance thanks to the development of pharmacotherapy. Most psychotropic medications act precisely on current symptoms rather than the cause: depression is treated with antidepressants, anxiety with tranquilizers, and delusions and psychomotor agitation with antipsychotics.

Nosological approach: searching for the root cause

The introduction of new treatment methods (malariotherapy, neurosurgery, shock therapy, antibiotics) required a revision of classifications and a transition to the nosological approach. Its essence is the identification of specific diseases (nosological entities) that share a common etiology, pathogenesis, symptomatology, and course.

Historical examples of identifying such diseases in the 19th century:

• General paresis (A.L.J. Bayle, 1822).
• Manic-depressive psychosis (J. Baillarger, J.-P. Falret, E. Kraepelin).
• Alcoholic polyneuritic psychosis (S.S. Korsakoff, 1887).
• Dementia praecox — schizophrenia (E. Kraepelin, E. Bleuler).

This approach made it possible to describe in detail the dynamics of disorders (rate and direction of changes) and outcome variants (from complete recovery to a stable defect or threat of death). However, the approach has been criticized. Karl Bonhoeffer, in his theory of exogenous reaction types, argued that different external influences can lead to identical mental disorders, reflecting individual response characteristics rather than the cause of the disease itself.

Synthesis of approaches and statistical pragmatism

In modern clinical practice, nosological and syndromological principles do not compete, but complement each other as a general clinical principle.

The structure of a full diagnosis includes:

1. Name of the nosological entity: provides an understanding of possible etiotropic therapy and determines the likely prognosis.
2. Leading syndrome at the time of examination: reflects the severity of the condition, the stage of the course, and determines the choice of symptomatic therapy to help the patient "here and now".

To regulate social, economic, and legal aspects at the state level, the pragmatic (statistical) principle is applied. It is based on formal criteria recognized by the majority of physicians. Classic examples are international classifications such as ICD-10 and DSM-IV. They are necessary for standardized statistical accounting, healthcare system planning, and resolving strict legal issues where the reliability of the diagnosis is of critical importance.

Class and exam questions

What else to study on this topic

• Historical contribution of E. Kraepelin and E. Bleuler to distinguishing schizophrenia (Dementia praecox).
• Detailed analysis of Karl Bonhoeffer's theory of exogenous reaction types and its significance.
• Organization of patient care depending on the leading clinical syndrome.
• The impact of the introduction of psychopharmacotherapy on the revival of the syndromological approach.

Other topics in "Chapter 18. Classification of Mental Disorders"

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.