Depression, non-fatal stroke and all-cause mortality in old age: a prospective cohort study of primary care patients.

Background: Depression is a risk factor for stroke and mortality but whether this also holds into old age is uncertain. We therefore studied the association of depression with the risk for non-fatal stroke and all-cause mortality in very old age.

Methods: A representative sample of 3085 primary care patients aged ≥ 75 years were serially assessed during a 6-year follow-up. The relation between depression (Geriatric Depression Scale >6, n=261) and relevant covariates including vascular risk factors and disease, functional and mild cognitive impairment and ApoE genotype on primary care givers information of incident stroke (n=209) and mortality (n=647) were assessed by Cox regression and by competing risk regressions.

Results: Depression was not independently associated with incident stroke in fully adjusted models that treated death as the competing event (subdistribution hazard ratio=0.80, 95% confidence interval=0.47 to 1.36). The risk associated with depression was similar for men and women, and for age groups 75-79, 80-84 and ≥ 85 years. In contrast, depression increased all-cause mortality rates, even after adjusting for a range of confounders (hazard ratio=1.31, 95% confidence interval=1.03 to 1.67).

Limitations: We have no information on past depressive episodes and cause of death.

Conclusions: In contrast to reports in younger populations, depression does not appear to increase stroke risk among the old and very old, but continuous to be a risk factor for all-cause mortality.