ORLANDO, FLA—Estimates of the frequency of major depression in the geriatric population, ranging from 2% to 5%, have been relatively low in community samples. “That clearly does not capture everyone who experiences what we would consider clinically significant depressive symptoms,” said Dan G. Blazer, MD, PhD. His earlier research of depressive symptoms among community-dwelling elders revealed that about 75% had no depressive symptoms, 25% had some form of depressive symptoms, and less than 1% of those age 60 or older actually suffered from major depression. “We parceled these symptoms into a number of different diagnoses, and there was one we called ‘minor depression,’ ” Dr. Blazer explained during his presentation at the 15th Annual Meeting of the American Association for Geriatric Psychiatry.

The current criteria used to identify those with clinically significant minor depression may leave many elders misdiagnosed or incorrectly treated. Antidepressant use has risen dramatically in older persons, from 4% in 1986 to 11% more recently, he noted. “Most antidepressants are still prescribed in this country for what primary care physicians would view as depression.” Dr. Blazer continued, “Somebody thinks these symptoms need to be treated. A lot of people in primary care are treating depressive symptoms that do not meet the criteria for depression, and we need to be concerned about that.” Dr. Blazer is Professor of Psychiatry and Behavioral Sciences at Duke University Medical Center.

DEFYING DEFINITION

Possibly, it’s subsyndromal depression that physicians are seeing. In order to define this syndrome, Dr. Blazer referred to the DSM-IV, which contains a definition of subsyndromal depression that is “a useful, operational definition for minor depression based on no data whatsoever—it basically just lowers the threshold from major depression.” Other standards such as the ICD-X propose a definition but, Dr. Blazer emphasized, “The ICD–X felt that minor or mild depression had mild or absent biological symptoms. How they figured that out, I have no idea, but that is their definition.” He also noted that in 1987 Snaith suggested that a biogenetic form of mild depression exists and anhedonia is the central reliable form of hypomelancholia or mild biogenic depression.

Others have suggested that subsyndromal depression is a variant of major depression, and Dr. Blazer acknowledged that epidemiologic studies of subthreshold depression may also capture those who are entering into or just emerging from an episode of major depression. Those patients probably constitute less than 50% of the individuals his team would consider to have mild or minor depression; many of the symptoms noted by his research group were what Dr. Blazer termed “residual symptoms,” which nonetheless had an impact on the lives of individuals.

“Except for the fact that patients exhibit symptoms that are less severe than those of major depression, we don’t know the answer. We can operationalize criteria, and that’s the way we further the field.” But, he cautioned, “We have to realize these criteria are not realities but are tools we are using to research the field even further.”

Other prevalence estimates of minor depression would fall somewhere between about 8% to 16% of individuals in the community older than 65, despite the varying definitions of subsyndromal depression, according to Dr. Blazer. “We [epidemiologists] don’t have to know what something is in order to count it. That suggests subsyndromal depression is something we’ve got to pay attention to, especially in older persons.”

Defining minor depression as meeting the criteria for clinically significant depression symptoms on the Center for Epidemiologic Studies Depression (CES-D) scale but not having a diagnosis of major depression, investigators in the Netherlands found that nonmajor depression is nearly twice as common in women and is apparent in 15% to 20% of those in the 65 and older age range. “In some terms,” said Dr. Blazer, “that’s as good as any at arriving at an operational criteria.”

In a hospital setting, Harold Koening found that 23% of older adults had clinically significant depressive symptoms. About 18% of patients in outpatient settings have what are probably clinically significant depressive symptoms using the Research Diagnostic Criteria (RDC) that do not fall into the diagnosis of major depression. Another study, led by Pat Parmelee, revealed that 30.5% of people in a long-term care setting had clinically significant, though less severe, depressive symptoms. “Clearly, the message here is that when you move from the community into treatment settings your frequency of so-called minor or subsyndromal depression increases,” observed Dr. Blazer.

“Something’s going on but we don’t know what,” Dr. Blazer conceded. “You may say we’re trying to label and realify a diagnosis called minor depression or subsyndromal depression, which is an umbrella term for people who are actually experiencing the normal spectrum of depressive symptoms.”

Dr. Blazer cited his recent study that found that in individuals with depression, women were protected against death. “We usually think of depression as being associated with increased rates of mortality, and we find just the opposite.” The authors suspect that this type of depression is a form of adaptive behavior and may be a biological or psychological response to protect women from future risk. “This is a preliminary study, and it brings us interesting things regarding evolutionary evidence,” Dr. Blazer commented.

Outlining the evolution of the current diagnosis of depression, Dr. Blazer observed that “Pre-Freud depressions that were considered clinically significant were those individuals who ended up in institutions and represented a very small percentage of the population. Freud took psychiatry from the institution to the community and from that we saw psychopathology encompassing a larger group of individuals.” However, he said, “That somewhat wide, very fuzzy description of depression and other psychiatric disorders made depression very difficult to study and therein came the emergence of the Feighner criteria, the RDC, and the DSM-III criteria.” However, use of the established criteria for depression does not capture everyone, and “that’s the point at which mild depression came into our nomenclature.”

Many of the symptoms that tend to comprise “war syndromes” (eg, Persian Gulf War Syndrome)—agitation, depression, sleep disturbance—are the same symptoms seen in minor depression. Dr. Blazer believes the construct of minor depression has been around much longer than the 10 years the term subsyndromal depression has been in use. “What’s the take-home message? Let’s not realify too quickly this diagnosis of minor depression or subsyndromal depression without realizing we’re throwing our umbrella out over a number of different conditions.” He suggests that individual symptoms be viewed more specifically, as well as their response to various interventions. His concern is that “When we label something like minor depression, our next logical step is to treat it with a medication.” He cautions that, with this approach, “we lose a very important message—there are social and psychosocial factors that contribute to the psychiatric morbidity we see, and we may not always be doing our patients a service by ignoring that through the mechanism of treating only by medication.”

—Heidi W. Moore

Suggested Reading
Hybels CF, Blazer DG, Pieper CF. Toward a threshold for subthreshold depression: an analysis of correlates of depression by severity of symptoms using data from an elderly community sample. Gerontologist. 2001;41:357-365.

Hybels CF, Pieper CF, Blazer DG. Sex differences in the relationship between subthreshold depression and mortality in a community sample of older adults. Am J Geriatr Psychiatry. 2002;10:283-291.

Snaith RP. The concepts of mild depression. Br J Psychiatry. 1987;150:387-393.

Sonnenberg CM, Beekman AT, Deeg DJ, van Tilburg W. Sex differences in late-life depression. Acta Psychiatr Scand. 2000;101:286-292.

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