When one thinks of all the conditions that are of concern in geriatric mental health, Alzheimer's Disease (AD) is certainly one of the most important. Although described in the early 1900s, little attention was focused upon the illness until the last decade. Almost certainly this attention is related to the increase in size of the elderly segment of the population. Understanding this population shift, taken with the estimate that perhaps as high as 10% or more of the population over the age of 80 may develop Alzheimer's Disease, some have been led to call AD "the disease of the century." In the final stages, AD victims lose all ability for self-care. As a result, the emotional and financial costs to families and to nations is likely to be staggering in the decades ahead.
Because these figures are frightening, AD has received (as it should) a good deal of publicity. A concern of those who deal with AD, however, is that it will become "overdiagnosed" without benefit of a thorough differential diagnosis. Although it is not the purpose of this column to explicate all the tests used for the diagnosis, suffice it to say that AD is a diagnosis of exclusion and one in which a battery of blood tests, psychological tests, and other procedures such as the CT scan and Positron Emission Tomography (PET) are used.
The need for a thorough differential diagnosis has become increasingly evident to me in my activities as a postdoctoral fellow on a psychogeriatric unit. In the elderly, one very common reversible condition that presents a picture very similar to AD is depression. The profoundly depressed individual is nonresponsive, and this lack of response may make them appear to be cogniti vely impaired. It should be noted that most persons in the early stages of AD are also depressed. Therefore, the differential diagnosis is doubly important. If someone has both AD and depression, treatment of the depression will allow for other approaches to be instituted which are aimed at maintaining cognitive functioning.