Psychological Disorders: Dementia of the Alzheimer Type

American Description
A. The development of multiple cognitive deficits manifested by both:

1. Memory impairment (impaired ability to learn new information or to recall previously learned information)

2. One (or more) of the following cognitive disturbances:
Aphasia (language disturbance)
Apraxia (impaired ability to carry out motor activities despite intact motor function)
Agnosia (failure to recognize or identify objects despite intact sensory function)
Disturbance in executive functioning (i.e., planning, organizing, sequencing, abstracting)


B. The cognitive deficits (above) cause significant impairment in social or occupational functioning and represent a significant decline from a previous level of functioning


C. The course is characterized by gradual onset and continuing cognitive decline.


D. The cognitive deficits are not due to any of the following:

1. Other central nervous system conditions that cause progressive deficits in memory and cognition (e.g., cerebrovascular disease, Parkinson's disease, Huntington's disease, subdural hematoma, normal-pressure hydrocephalus, brain tumor)

2. Systemic conditions that are known to cause dementia (e.g., hypothyroidism, vitamin B12 or folic acid deficiency, niacin deficiency, hypercalcemia, neurosyphilis, HIV infection)

3. Substance-induced conditions


E. The cognitive deficits do not occur exclusively during the course of a delirium.


F. The disturbance is not better accounted for by another Axis I disorder (e.g., Major Depressive Disorder, Schizophrenia)

Problem Areas (When Initially Diagnosed)
Socio-Economic:
Moderately impaired homemaking
Moderately impaired money management
Requires voluntary institutional care (placement in supervised residence or nursing home)

Depression:
Significant loss of interest and motivation
Significant irritability or hostility
Significant problem with concentration

Intellectual Impairment:
Significant problem with memory or learning
Significant decrease in speech and movement
Significant problem with grooming and hygiene
Significant confusion as to date, place, or person

Onset and Course
Late onset (after age 65 years) is much more common than early onset.
At age 65, 0.6% of males and 0.8% of females have Alzheimer's Dementia.
At age 90, 21% of males and 25% of females have Alzheimer's Dementia.
In the first years of illness, few motor and sensory signs are associated with Alzheimer's Dementia. Later in the course, myoclonus and gait disorder may appear.
Usually the onset is insidious, with early deficits in recent memory followed by the development of aphasia, apraxia, and agnosia after several years.
Some individuals may show personality changes or increased irritability in the early stages. In the later stages of the disease, individuals may develop gait and motor disturbances and eventually become mute and bedridden.
On average, death occurs 8-10 years from onset of symptoms.



European Description
Alzheimer's disease is a primary degenerative cerebral disease of unknown etiology, with characteristic neuropathological and neurochemical features. It is usually insidious in onset and develops slowly but steadily over a period of years. This period can be as short as 2 or 3 years, but can occasionally be considerably longer. The onset can be in middle adult life or even earlier (Alzheimer's disease of presenile onset), but the incidence is higher in later life (Alzheimer's disease of senile onset). In cases with onset before the age of 65-70, there is the likelihood of a family history of a similar dementia, a more rapid course, and prominence of features of temporal and parietal lobe damage, including dysphasia or dyspraxia. In cases with a later onset, the course tends to be slower and to be characterized by more general impairment of higher cortical functions. Patients with Down's syndrome are at high risk of developing Alzheimer's disease.

There are characteristic changes in the brain: a marked reduction in the population of neurons, particularly in the hippocampus, substantia innominata, locus ceruleus, and temporoparietal and frontal cortex; appearance of neurofibrillary tangles made of paired helical filaments; neuritic (argentophil) plaques, which consist largely of amyloid and show a definite progression in their development (although plaques without amyloid are also known to exist); and granulovacuolar bodies. Neurochemical changes have also been found, including a marked reduction in the enzyme choline acetyltransferase, in acetylcholine itself, and in other neurotransmitters and neuromodulators.

As originally described, the clinical features are accompanied by the above brain changes. However, it now appears that the two do not always progress in parallel: one may be indisputably present with only minimal evidence of the other. Nevertheless, the clinical features of Alzheimer's disease are such that it is often possible to make a presumptive diagnosis on clinical grounds alone.

Dementia in Alzheimer's disease is at present irreversible.

Diagnostic Guidelines
The following features are essential for a definite diagnosis:

(a) Presence of a dementia as described above.

(b) Insidious onset with slow deterioration. While the onset usually seems difficult to pinpoint in time, realization by others that the defects exist may come suddenly. An apparent plateau may occur in the progression.

(c) Absence of clinical evidence, or findings from special investigations, to suggest that the mental state may be due to other systemic or brain disease which can induce a dementia (e.g. hypothyroidism, hypercalcaemia, vitamin B12 deficiency, niacin deficiency, neurosyphilis, normal pressure hydrocephalus, or subdural haematoma).

(d) Absence of a sudden, apoplectic onset, or of neurological signs of focal damage such as hemiparesis, sensory loss, visual field defects, and incoordination occurring early in the illness (although these phenomena may be superimposed later).

In a certain proportion of cases, the features of Alzheimer's disease and vascular dementia may both be present. In such cases, double diagnosis (and coding) should be made. When the vascular dementia precedes the Alzheimer's disease, it may be impossible to diagnose the latter on clinical grounds.

Includes:
* primary degenerative dementia of the Alzheimer's type

Differential Diagnosis
Consider: a depressive disorder (F30-F39); delirium (F05); organic amnesic syndrome (F04); other primary dementias, such as in Pick's, Creuzfeldt-Jakob or Huntington's disease (F02.-); secondary dementias associated with a variety of physical diseases, toxic states, etc. (F02.8); mild, moderate or severe mental retardation (F70-F72).

Dementia in Alzheimer's disease may coexist with vascular dementia (to be coded F00.2), as when cerebrovascular episodes (multi-infarct phenomena) are superimposed on a clinical picture and history suggesting Alzheimer's disease. Such episodes may result in sudden exacerbations of the manifestations of dementia. According to postmortem findings, both types may coexist in as many as 10-15% of all dementia cases.