Diabetes Mellitus Linked to Depressive Symptoms in Well-Functioning Older Adults

June 13, 2007 — Diabetes mellitus is linked to depressive symptoms in well-functioning older adults, according to the results of the Health, Aging, and Body Composition (Health ABC) Study published in the June 11 issue of the Archives of Internal Medicine.
"Cross-sectional studies find an elevated prevalence of depression among subjects with diabetes mellitus (DM)," write Cinzia Maraldi, MD, from the University of Florida in Gainesville and colleagues from the Health ABC Study. "The causal mechanisms and temporal sequence of this association have not been clearly delineated. This study investigated the prospective relationship between DM and depressive symptoms."
The Health ABC Study was a cohort study of community-dwelling adults, aged 70 to 79 years, without baseline depressive symptoms who were living in the metropolitan areas of Memphis, Tennessee, and Pittsburgh, Pennsylvania. Incident depressed mood was defined as antidepressant use or presence of depressive symptoms (score ≥ 10 on a 10-item subset of the Center for Epidemiological Studies Depression Scale [CES-D]) at follow-up visits. Recurrent depressed mood was defined as presence of incident depressed mood at 2 consecutive annual clinic visits.
At baseline, the investigators evaluated glycosylated hemoglobin (HbA1c) level, DM status (absent, controlled [HbA1c level, < 7%], or uncontrolled [HbA1c level, ≥ 7%]), and DM-related comorbidities in 2522 participants. Depressive events risk was estimated from discrete time survival analysis. Mean duration of follow-up was 5.9 years.
During follow-up, participants with DM had a higher age-, sex-, race-, and site-adjusted incidence of depressed mood (23.5% vs 19.0%; P = .02) and of recurrent depressed mood (8.8% vs 4.3%; P < .001) than did those without DM. Although DM was associated with an increased risk for incident depressed mood (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.07 - 1.61), adjustment for DM-related comorbidities reduced this increased risk (OR, 1.20; 95% CI, 0.97 - 1.48).
There was a stronger relationship between DM and recurrent depressed mood (OR, 1.91; 95% CI, 1.32 - 2.76), especially in participants with poor glycemic control.
"Among well-functioning older adults, DM is associated with increased risk of depressive symptoms," the authors write. "In particular, older adults with DM had an almost 2-fold increased risk of developing recurrent depressed mood. The increased risk of depressed mood was mainly observed among participants with DM and poor glycemic control, and HbA1c was an independent predictor of recurrent depressed mood among subjects with DM."
Study limitations include failure to record episodes of depressive symptoms between clinic visits that resolved during this period, CES-D capture of presence of depressed mood only in the past week, lack of data on depressive episodes before study entry, lack of data on the use of nonpharmacologic depression treatment, lack of data on information about change with time and about severity of DM complications, inability to completely rule out potential confounders, and narrow age range of the study inclusion criteria limiting the generalizability of the results.
"As the life expectancy of older Americans increases, DM is becoming a disease of older adults," the authors conclude. "Depression is among [the] key geriatric outcomes that strongly impact health-related quality of life of older adults but that are often underdiagnosed and undertreated. From this point of view, our results underline the importance of a clinical approach to the patient with DM that includes an appropriate screening for early detection and treatment of depressive symptoms."
The Intramural Research program of the National Institutes of Health, National Institute on Aging, and the National Heart, Lung, and Blood Institute supported this study. The authors have disclosed no relevant financial relationships.
Arch Intern Med. 2007;167:1137-1144.