Alzheimer's Disease: Diagnosis and Treatment

Diagnosis

Since the pathologic findings cannot be demonstrated except by autopsy (or, rarely, by brain biopsy), evaluation of the patient with suspected Alzheimer's disease is generally focused on identifying potentially treatable disorders that produce cognitive deficits.

Neuroimaging, particularly magnetic resonance imaging, can help rule out potentially treatable causes of dementia such as vascular dementia, hydrocephaly, and brain tumors, even in the absence of focal findings. Tests of potential metabolic abnormalities (eg, hypothyroidism, vitamin B₁₂ deficiency, electrolyte abnormalities) should be included in the workup.

Severe sleep disorders, disorders of liver and renal function, and various medications can produce cognitive effects. Strong consideration should be given to possible depression (pseudodementia). Neurospychiatric testing may be useful to aid in the diagnosis of Alzheimer's disease or to evaluate its course. Such testing may be particularly helpful if the presentation is atypical.

Overlap with other causes of dementia does occur; eg, Lewy body dementia and Pick's disease. However, because treatment is based on symptoms, biopsy is not commonly performed.

Treatment

People who exercise, participate in intellectually stimulating activities, and remain active in social networks appear to be at lower risk for Alzheimer's,¹¹ and those affected may slow its progression through these activities.

Drugs may have a modest effect.

• Memantine, an N-methyl-D-aspartate receptor antagonist, along with galantamine, may slow the loss of mental and physical function. Memantine has modest effects in patients with moderate-to-advanced disease.
• Preliminary evidence suggests that nonsteroidal anti-inflammatory drugs (NSAIDs) may provide some protection against Alzheimer's disease.¹² This finding requires further study.
• The benefits of acetylcholinesterase inhibitors, such as donepezil, have been questioned, are small and may not be greater than placebo.¹³
• Ginkgo biloba may provide a modest benefit. A ginkgo biloba extract known as EGb761 appears to act by a mechanism similar to that of cholinesterase inhibitors for mild-to-moderate Alzheimer's disease,¹⁴ and showed a small benefit over a placebo in clinical trials.^15-17