Dementia of the Alzheimer’s Type

Introduction & Clinical Features

Dementia of the Alzheimer’s Type (DAT) is the most common form of dementia Opens in new window, with the Alzheimer’s Association (2006) estimating that approximately 4.5 million Americans currently have DAT, with a projection for as many as 16 million people by 2050.

The course and clinical features of DAT are parallel to those discussed for dementia in general. Typically, the early course of DAT is difficult to ascertain because the patient is usually an unreliable informant, and the early signs may be so subtle as to go unnoticed even by the patient’s closest associates.

These early features include impaired memory, difficulty with problem-solving, preoccupation with long-past events, decreased spontaneity, and an inability to respond to the environment with the patient’s usual speed and accuracy. Patients may forget names, misplace household items, or forget what they were about to do. Often the individuals have insight into these memory deficits and occasionally convery their concerns to family members.

Such responses as “You’re just getting older” and “I do that sometimes myself” are common from those so informed, and as a result the patient becomes depressed, which can further affect cognitive functioning.

Anomia, or difficulty with word finding, is common in this middle stage of Alzheimer’s disease. Eventually the patient develops schemes, word associations, and excuses (“I never was very good in math”) to assist in retention and cover up deficits. The patient may also employ family members as a surrogate memory.

Because memory loss is usually most obvious for newly acquired material, the patient tries to avoid unfamiliar activities. Typically, the patient is seen by the mental health professional when confusion, aggression, wandering, or some other socially undesirable behavior ensues.

At that time, disorder of perception and language may appear. The patient often turns to a spouse to answer questions posed during the history-taking. By this time the affected individual has lost insight into his or her dementia and abandons attempt to compensate for memory loss.

Finally, in the late stage of Alzheimer’s disease, physical and cognitive effects are marked. Disorders of gait, extremity paresis and paralysis, seizures, peripheral neuropathy, extrapyramidal signs, and urinary incontinence are seen, and the patient is often no longer ambulatory.

The aimless wandering of the middle stage has been replaced by a mute, bedridden state and decorative posture. Myoclonus occasionally occurs. Significantly, affective disturbances remain a distinct possibility throughout the course of the illness. DAT progresses at a slow pace for 8–10 years to a state of complete helplessness.

DSM-IV-TR Diagnostic Criteria
294.1x Dementia of the Alzheimer Type
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:
  1. aphasia (language disturbance)
  2. apraxia (impaired ability to carry out motor activities despite intact motor function)
  3. agnosia (failure to recognize or identify objects despite intact sensory function)
  4. disturbance in executive functioning (i.e., planning, organizing, sequencing, abstracting)
B.The cognitive deficits in criteria A1 and A2 each 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 in criteria A1 and A2 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 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).
Code based on presence or absence of a clinically significant behavioral disturbance

294.10 Without behavioral disturbance: if the cognitive disturbance is not accompanied by any clinically significant behavioral disturbance.

294.11 With behavioral disturbance: if the cognitive disturbance is accompanied by a clinically significant behavioral disturbance (e.g., wandering, agitation).

Specify subtype:
With Early Onset: if onset is at age 65 years or below
With Late Onset; if onset is after age 65 years
Coding note: Also code 331.0 Alzheimer’s disease on Axis III. Indicate other prominent clinical features related to the Alzheimer’s disease on Axis I (e.g., 293.83 Mood Disorder Due to Alzheimer’s Disease, With Depressive Features, and 310.1 Personality Change Due to Alzheimer’s Disease, Aggressive Type. Code based on type of onset and predominant features).
Source: from the Diagnostic and Statistical Manual of Mental Disorders, 4th ed., Text Rev. Copyright 2000 American Psychiatric Association.
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