Criteria Differentiate Alzheimer’s Depression From Other Types

The depression that sometimes accompanies Alzheimer’s disease has long been problematic from a diagnostic viewpoint. It doesn’t seem to fit the criteria for DSM-IV major depressive disorder, yet the DSM-IV doesn’t contain criteria for Alzheimer’s depression per se.

So some authorities in the field of Alzheimer’s depression decided to see whether they might be able to reach a consensus on how Alzheimer’s depression differs from major depression and to draw up provisional diagnostic criteria for the former. They have now managed to do so, they reported in the March-April issue of the American Journal of Geriatric Psychiatry (AJGP).

The authorities include Jason Olin, Ph.D., and Barry Lebowitz, Ph.D., of the National Institute of Mental Health’s Adult and Geriatric Treatment and Preventive Interventions Research Branch; Ira Katz, M.D., Ph.D., a professor of psychiatry at the University of Pennsylvania; Barnett Meyers, M.D., a professor of psychiatry at Cornell University; Lon Schneider, M.D., a professor of psychiatry at the University of Southern California; and other experts on the subject who participated in the NIMH Depression of Alzheimer Disease Workshop.

Probably the most striking point that Olin and his coworkers have come to agree on is that the depression that often accompanies Alzheimer’s is definitely not the same as major depressive disorder. True, both kinds of depression share a number of symptoms, such as depressed mood, decreased pleasure in response to one’s usual activities, disruption in sleep, feelings of worthlessness and guilt, diminished ability to concentrate, suicidal ideation, and so forth. But the withdrawal and social isolation observed in depressed Alzheimer’s patients are not the same as those displayed in patients with a major depressive disorder.

As Olin explained to Psychiatric News, “The consensus of the group was that the terminology used in DSM-IV was not written with consideration of the apathy often seen in Alzheimer’s disease. Major depression’s criterion is stated as follows: ‘Marked diminished interest or pleasure in all, or almost all, activities most of the day, nearly every day.’ For depression of Alzheimer’s disease we state: ‘Decreased positive affect or pleasure in response to social contacts and usual activities.’ ”

Another difference between Alzheimer’s depression and major depressive disorder, Olin and his colleagues concurred, is that only three pertinent symptoms need to be present for at least two weeks to constitute a diagnosis, whereas five or more pertinent symptoms must be present for at least two weeks to constitute major depression. The reason, Olin explained, is “that the criteria for major depression set a level of severity that is higher than much of the depression seen in Alzheimer’s disease.”

For Alzheimer’s depression to be diagnosed, the experts agreed, a person must have already been diagnosed with Alzheimer’s according to DSM-IV criteria.

Who will benefit from these provisional diagnostic criteria? First, scientists researching Alzheimer’s depression treatments. “The immediate goal,” Olin said, “was to get out to the field a set of standardized criteria so that treatment research could be more easily generated.”

Dilip Jeste, M.D., a member of the NIMH Depression of Alzheimer Disease Workshop and editor of AJGP, agreed. “Hopefully the criteria will jump-start the field by providing a more consistent target for treatment development.”

Alzheimer’s patients who suffer from depression will probably also benefit from the provisional criteria. The reason, Jeste explained, is that existing diagnostic criteria for major depression weren’t always sensitive enough to detect Alzheimer’s depression and therefore led to under-recognition and under-treatment. Olin made a similar comment: “If we only looked at individuals with Alzheimer’s disease who met DSM criteria for major depression, a substantial group of others would be excluded from possible treatment.”

Olin and his team drafted these provisional diagnostic yardsticks for Alzheimer’s depression by using methods similar to those used by experts who draft DSM diagnoses. For instance, a team of investigators was formed that had expertise in both dementia and late-life-depression research. Before starting the process of criteria development, the team created a Web site that provided for the distribution of review articles. To facilitate discussion, an initial draft of diagnostic criteria was developed by five of the groups in the style of DSM-IV major depressive episode. Through a process of conference calls, e-mail discussions, and circulation of multiple drafts, the criteria were finalized.

“I definitely hope that investigators will take advantage of this first step and use the criteria to increase our understanding of the depression found in Alzheimer’s disease,” Olin said. “For instance, perhaps we will come up with enough evidence to show a causal link between the depression in Alzheimer’s and Alzheimer’s itself.”

The study, “National Institute of Mental Health Provisional Diagnostic Criteria for Depression of Alzheimer’s Disease,” is posted on the Web at http://ajgp.psychiatryonline.org under the “March-April 2002” issue. The journal is published by the American Association for Geriatric Psychiatry. ▪

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