Deborah Brauser

March 22, 2012

March 22, 2012 (Washington, DC) — Fasting blood glucose may be a biomarker of depression in elderly patients, new research suggests.

In one of the first studies to find such a correlation, investigators found that impaired fasting blood sugar level was a significant predictor of depressive symptoms in a sample of 45 adults older than 64 years who did not have a previous history of diabetes.

"We found the findings to be unexpected and think clinicians should have a heightened awareness of this possibility in their prediabetic geriatric patients — and not just in their diabetic ones," lead author Jaclynn M. Moskow, a third-year medical student at Nova Southeastern University College of Osteopathic Medicine in Fort Lauderdale, Florida, told Medscape Medical News.

Jaclynn Moskow

"Although the reason for this association is unclear at this time, it may be related to a particular vascular process. It could be that there is some sort of underlying vascular change in the brain that is responsible," she added.

Moskow presented the study results here at the American Association for Geriatric Psychiatry (AAGP) 2012 Annual Meeting.

Significant Predictor

Previous research, including studies reported on by Medscape Medical News, have shown that depression and diabetes are highly correlated.

"Diabetic individuals are more likely to have depression than nondiabetics, and it has been shown that depression increases the risk of developing diabetes," write the researchers.

In fact, an earlier meta-analysis "showed that depressed adults were 37% more likely to develop type 2 diabetes than non-depressed adults," report the investigators. Another study "showed that in diabetics, total healthcare expenditures for individuals with depression were 4.5 times higher than that for individuals without depression."

"There's a lot out there about depression and diabetes. So we were interested in examining the relationship between blood sugar levels and depression in a population that did not have diabetes," said Moskow.

A total of 45 older adults who did not have diabetes (mean age, 76.2 years) were recruited for this pilot study. Levels of fasting blood glucose and of fasting insulin, along with body mass index (BMI), were recorded for each participant (mean BMI, 27.5).

The self-reported 20-item Center for Epidemiologic Studies Depression Scale (CES-D) questionnaire was used to assess mood.

Results showed that after adjusting for age, sex, BMI, and insulin levels, fasting blood glucose was still a significant predictor of depressive symptoms (P = .02).

The mean fasting glucose level was 95.7 (range, 72 - 135; standard deviation [SD], 14.1). The mean CES-D score was 11.7 (range, 0 - 35; SD, 8.9).

"I'm hoping these findings can eventually be replicated in a much bigger study," said Moskow.

Raises Questions

"This study showed that blood glucose was associated with low-level symptoms of depression, although not depression itself," George Alexpoulos, MD, professor of psychiatry and director of the Weill-Cornell Institute of Geriatric Psychiatry in White Plains, New York, told Medscape Medical News.

"This was an interesting association, but the specificity of the association was in question. We have to ask: does impaired level of glucose cause depressive symptoms? Or does it cause physical symptoms such as fatigue, demoralization, lack of motivation, or insomnia that all fall under the umbrella of depression? There wasn't enough severity there to be able to qualify for depression," he said.

Dr. Alexpoulos, who was the designated discussant during the poster's presentation, noted that it can often be difficult to determine whether this patient population is actually experiencing symptoms of depression rather than symptoms that could really be associated with loneliness or malaise.

"We know that serious depression is associated with some neurobiological abnormalities and responds to antidepressants. Depressive symptoms tend to be unstable and often respond to environmental interventions. And it's not clear if they belong to the same continuum, although they may be disabling," he said.

This study was supported by a small internal grant from Nova Southeastern University Health Professions Division. Moskow and Dr. Alexpoulos have disclosed no relevant financial relationships.

American Association for Geriatric Psychiatry (AAGP) 2012 Annual Meeting. Abstract EI-29. Presented March 17, 2012.

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