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09-04-2012 | Diabetes | Article

Depression impacts on dementia risk in diabetes

Abstract

Free abstract

MedWire News: Depression is associated with a significantly increased risk for dementia among patients with Type 2 diabetes, show study findings.

Comorbid depression was associated with an approximately two-fold increase in risk for dementia compared with patients with diabetes alone, report Wayne Katon (University of Washington, USA) and colleagues.

"Poor glycemic control, vascular risk factors, and vascular changes associated with depression in patients with diabetes may increase the risk of dementia," say the researchers. "Since depression affects up to 20% of diabetic patients, it is critical to estimate if it is a risk factor for dementia since it is potentially modifiable."

The team analyzed data from the Diabetes and Aging Study, a cohort investigation focusing on medical issues particularly relevant to older diabetes patients. Approximately 20,000 diabetes patients (mean age 58.8 years) self-reported information regarding a range of social, behavioral, clinical, and health-related factors that might influence diabetes outcomes.

The main predictor of interest was having clinically significant depression symptoms at baseline, as determined by a score of 10 or more on the Patient Health Questionnaire 8, and either a physician diagnosis of depression in the 12 months prior to baseline survey, or a prescription of one or more anti-depressant medications.

Proportional hazard modeling was used to estimate the association between depression and diagnosis of incident dementia (based on the International Classification of Diseases diagnostic codes) in years 3 through 5 of follow-up.

As reported in the Archives of General Psychiatry, 3766 (19.6%) and 238 (1.2%) of the 19,239 diabetes patients met the criteria for clinically significant depression and dementia, respectively.

Of the patients with comorbid depression, 80 (2.1%) met the criteria for dementia giving an incidence rate of 5.5 per 1000 person-years. And of the 15,473 participants without depression, 158 (1.0%) met the dementia criteria, giving an incidence rate of 2.6 cases per 1000 person-years.

Further analysis revealed that depression at baseline was associated with a 2.02-fold greater risk for dementia compared with those without diabetes, after adjustment for covariates.

"There are several biologic mechanisms that could link depression and dementia. Dysregulation of the hypothalamic-pituitary axis associated with depression has been linked to higher glucocorticoid production and impaired negative feedback," say the researchers. "Dysregulation of cortisol may damage brain areas involved in cognition such as the hypothalamus as well as decrease neurogenesis in key brain areas."

"Given that depression is potentially modifiable, future studies are needed to further evaluate whether effective depression interventions reduce the risk of dementia and identify the mechanisms that may explain our observation," they conclude.

MedWire (www.medwire-news.md) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012

By Sally Robertson