JAMA Psychiatry: Dementias Topic Collection

Association of Depression With Increased Risk of Dementia in Patients With Type 2 Diabetes The Diabetes and Aging Study Depression and Increased Risk of Dementia in T2DM

Katon W, Lyles CR, Parker MM, et al. — Sun, 01 Apr 2012 00:00:00 GMT

Context

Although depression is a risk factor for dementia in the general population, its association with dementia among patients with diabetes mellitus has not been well studied.

Objective

To determine whether comorbid depression in patients with type 2 diabetes increases the risk of development of dementia.

Design

The Diabetes and Aging Study was a cohort investigation that surveyed a racially/ethnically stratified random sample of patients with type 2 diabetes.

Setting

A large, integrated, nonprofit managed care setting in Northern California.

Participants

A sample of 19 239 diabetes registry members 30 to 75 years of age.

Main Outcome Measures

The Patient Health Questionnaire 8, International Classification of Diseases, Ninth Revision (ICD-9) diagnoses of depression, and/or antidepressant prescriptions in the 12 months prior to baseline were used to identify prevalent cases of depression. Clinically recognized dementia was identified among subjects with no prior ICD-9 Clinical Modification (ICD-9-CM) diagnoses of dementia. To exclude the possibility that depression was a prodrome of dementia, dementia diagnoses were only based on ICD-9-CM diagnoses identified in years 3 to 5 postbaseline. The risk of dementia for patients with depression and diabetes relative to patients with diabetes alone was estimated using Cox proportional hazard regression models that adjusted for sociodemographic, clinical, and health risk factors and health use.

Results

During the 3- to 5-year period, 80 of 3766 patients (2.1%) with comorbid depression and diabetes (incidence rate of 5.5 per 1000 person-years) vs 158 of 15 473 patients (1.0%) with diabetes alone (incidence rate of 2.6 per 1000 person-years) had 1 or more ICD-9-CM diagnoses of dementia. Patients with comorbid depression had a 100% increased risk of dementia during the 3 to 5 years postbaseline (adjusted hazard ratio, 2.02; 95% confidence interval, 1.73-2.35).

Conclusion

Depression in patients with diabetes was associated with a substantively increased risk for development of dementia compared with those with diabetes alone.

Midlife vs Late-Life Depressive Symptoms and Risk of Dementia Differential Effects for Alzheimer Disease and Vascular Dementia Depressive Symptoms and Risk of Dementia

Barnes DE, Yaffe K, Byers AL, et al. — Tue, 01 May 2012 00:00:00 GMT

Context

Depression and dementia are common in older adults and often co-occur, but it is unclear whether depression is an etiologic risk factor for dementia.

Objective

To clarify the timing and nature of the association between depression and dementia.

Design

We examined depressive symptoms assessed in midlife (1964-1973) and late life (1994-2000) and the risks of dementia, Alzheimer disease (AD), and vascular dementia (VaD) (2003-2009) in a retrospective cohort study. Depressive symptoms were categorized as none, midlife only, late life only, or both. Cox proportional hazards models (age as timescale) adjusted for demographics and medical comorbidities were used to examine depressive symptom category and risk of dementia, AD, or VaD.

Setting

Kaiser Permanente Medical Care Program of Northern California.

Participants

Thirteen thousand five hundred thirty-five long-term Kaiser Permanente members.

Main Outcome Measure

Any medical record diagnosis of dementia or neurology clinic diagnosis of AD or VaD.

Results

Subjects had a mean (SD) age of 81.1 (4.5) years in 2003, 57.9% were women, and 24.2% were nonwhite. Depressive symptoms were present in 14.1% of subjects in midlife only, 9.2% in late life only, and 4.2% in both. During 6 years of follow-up, 22.5% were diagnosed with dementia (5.5% with AD and 2.3% with VaD). The adjusted hazard of dementia was increased by approximately 20% for midlife depressive symptoms only (hazard ratio, 1.19 [95% CI, 1.07-1.32]), 70% for late-life symptoms only (1.72 [1.54-1.92]), and 80% for both (1.77 [1.52-2.06]). When we examined AD and VaD separately, subjects with late-life depressive symptoms only had a 2-fold increase in AD risk (hazard ratio, 2.06 [95% CI, 1.67-2.55]), whereas subjects with midlife and late-life symptoms had more than a 3-fold increase in VaD risk (3.51 [2.44-5.05]).

Conclusions

Depressive symptoms in midlife or in late life are associated with an increased risk of developing dementia. Depression that begins in late life may be part of the AD prodrome, while recurrent depression may be etiologically associated with increased risk of VaD.