The Status of Therapy for Alzheimer's Disease

Article excerpt

INTRODUCTION

Alzheimer's disease (AD) is a chronic pathology representing a severe neurodegenerative disease that progressively and profoundly impairs intellectual functioning; it is the most common etiology of dementia in adult life. (Definitive features of dementia are listed in Table 1.) AD, as the fifth most common cause of death in the United States, reduces life span significantly. It is estimated to afflict 5% of people by the age of 65 and 20% of people who live to 80 years of age or older.

TABLE 1

DEFINITION AND CRITERIA FOR STATE OF DEMENTIA

Dementia is a process that in its advanced stages results in a global deterioration of mental functioning in the intellectual, emotional, and behavioral aspects.

An operational definition requires a serious alteration in at least three of the five following areas: (1) cognition; (2) memory; (3) language; (4) visual-spatial skills; (5) personality.

The public health impact of Alzheimer's disease is expected to continue increasing as long as the proportion of the population in the critical age group is expanding. The estimated cost of this disease in 1987 was over $34 billion.

AD is a disease about which pharmacists should be well informed, as it is one of the most common and serious chronic pathologies of elderly persons. Pharmacists will have increasing future involvement, because drug therapies for AD likely will multiply. Pharmacotherapy with adjunctive psychotropic agents to treat well-defined target symptoms is appropriate now for managing several nonspecific mental symptoms, including agitation, depression, and anxiety. Some patients can now derive specific benefit for cognitive impairments, because of the recent Food & Drug Administration approval of tacrine for treating this condition.

Besides participating in Alzheimer support groups, families of AD patients need to receive educational aid from health-care professionals. Current and future pharmacotherapy programs should emphasize education and support for AD patients' caregivers, who are vital to the proper delivery of therapy.

DIAGNOSIS OF ALZHEIMER'S DISEASE

Alzheimer pathology is characterized by the presence of two lesions demonstrable only upon a microscopic examination of the brain: neuritic (senile) plaques and neurofibrillary tangles. Both lesions can be found in the brain of older persons not having dementia, but they are much more common in the neocortex and the hippocampus of Alzheimer patients.

Also characteristic are deposits of amyloid in brain parenchymal blood vessels, as well as in the plaques, and the degeneration of specific populations of cholinergic nerve cells, especially of the basal forebrain (nucleus basalis of Mynert). Ultimately, a definitive diagnosis depends on the postmortem confirmation of such pathological features.

Thus, clinical diagnosis of AD during life presents a serious and important problem. It can be made only presumptively, by exclusion of other entities, upon combining the clinical history with physical and neurologic examinations, accompanied by some appropriate laboratory evaluations. With the dominant feature of this disease being the impairment of cognition, diagnosis customarily involves careful evaluation of cognitive function, usually via formal neuropsychological performance testing. It is obviously important that certain treatable dementias be considered (Table 2).

TABLE 2

RELATIVE INCIDENCE OF ALZHEIMER'S VERSUS OTHER DEMENTIAS BY ETIOLOGY AMONG 406 CONSECUTIVE CASES

Etiologic classification--Percent of total

A. Possibly reversible--(20.2)

1. Pseudodementia (depression)--7.1

2. Normal pressure hydrocephalus--5.4

3. Resectable mass lesions--3.7

4. Drug toxicity--2.0

5. Others--2.0

B. Probably irreversible--(79.8)

1. Alzheimer's disease--48.5

2. Alcoholism--10.6

3. Multi-infarct type--9. …