A Z Psychiatry 


Ray's Web Encyclopedia of Mental Health



The ICD-10 Classification of Mental and Behavioural Disorders
World Health Organization, Geneva, 1992


A general description of dementia is given here, to indicate the minimum requirement for the diagnosis of dementia of any type, and is followed by the criteria that govern the diagnosis of more specific types.

Dementia is a syndrome due to disease of the brain, usually of a chronic or progressive nature, in which there is disturbance of multiple higher cortical functions, including memory, thinking, orientation, comprehension, calculation, learning capacity, language, and judgement. Consciousness is not clouded. Impairments of cognitive function are commonly accompanied, and occasionally preceded, by deterioration in emotional control, social behaviour, or motivation. This syndrome occurs in Alzheimer's disease, in cerebrovascular disease, and in other conditions primarily or secondarily affecting the brain.

In assessing the presence or absence of a dementia, special care should be taken to avoid false-positive identification: motivational or emotional factors, particularly depression, in addition to motor slowness and general physical frailty, rather than loss of intellectual capacity, may account for failure to perform.

Dementia produces an appreciable decline in intellectual functioning, and usually some interference with personal activities of daily living, such as washing, dressing, eating, personal hygiene, excretory and toilet activities. How such a decline manifests itself will depend largely on the social and cultural setting in which the patient lives. Changes in role performance, such as lowered ability to keep or find a job, should not be used as criteria of dementia because of the large cross-cultural differences that exist in what is appropriate, and because there may be frequent, externally imposed changes in the availability of work within

If depressive symptoms are present but the criteria for depressive episode (F32.0-F32.3) are not fulfilled, they can be recorded by means of a fifth character. The presence of hallucinations or delusions may be treated similarly.

.x0 Without additional symptoms
.x1 Other symptoms, predominantly delusional
.x2 Other symptoms, predominantly hallucinatory
.x3 Other symptoms, predominantly depressive
.x4 Other mixed symptoms


Diagnostic Guidelines

The primary requirement for diagnosis is evidence of a decline in both memory and thinking which is sufficient to impair personal activities of daily living, as described above. The impairment of memory typically affects the registration, storage, and retrieval of new information, but previously learned and familiar material may also be lost, particularly in the later stages. Dementia is more than dysmnesia: there is also impairment of thinking and of reasoning capacity, and a reduction in the flow of ideas. The processing of incoming information is impaired, in that the individual finds it increasingly difficult to attend to more than one stimulus at a time, such as taking part in a conversation with several persons, and to shift the focus of attention from one topic to another. If dementia is the sole diagnosis, evidence of clear consciousness is required. However, a double diagnosis of delirium superimposed upon dementia is common (F05.1). The above symptoms and impairments should have been evident for at least 6 months for a confident clinical diagnosis of dementia to be made.

Differential Diagnosis
Consider: a depressive disorder (F30-F39), which may exhibit many of the features of an early dementia, especially memory impairment, slowed thinking, and lack of spontaneity; delirium (F05); mild or moderate mental retardation (F70-F71); states of subnormal cognitive functioning attributable to a severely impoverished social environment and limited education; iatrogenic mental disorders due to medication (F06.-).

Dementia may follow any other organic mental disorder classified in this block, or coexist with some of them, notably delirium (see F05.1).

ICD-10 copyright 1992 by World Health Organization.
AZ Psychiatry copyright (www.azpsychiatry.info) by Dr. Manaan Kar Ray