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Depressive symptoms causally linked to CHD, not stroke
A dose-response relationship may exist between depressive symptoms and CHD, but an association between depressive symptoms and stroke appears to be partly or entirely retrocausal, according to data in a recent prospective cohort study.
Researchers evaluated 10,036 participants enrolled in the Whitehall 2 Study, a cohort study of CVD among civil servants in 20 London-based departments. The participants, with a mean age of 44.4 years at the initiation of the study (range, 35-55 years), were assessed for 20 years.
At different phases of the study, the participants responded up to six times to a 30-question General Health Questionnaire (GHQ-30), and also received the 20-item Center for Epidemiologic Studies Depression Scale (CES-D) during the final phase. A score of 5 or higher on the GHQ-30 was classified as GHQ caseness, whereas a score of 16 or higher on the CES-D scale was categorized as CES-D caseness. Besides these measurements, the participants were followed for incidence of major coronary events, including coronary death, nonfatal MI and stroke death/morbidity, during four 5-year and three 10-year periods.
GHQ-30 caseness was observed in approximately 23% of participants across the 5- and 10-year cycles, whereas CES-D caseness was 15%. After adjustment for age, sex and ethnicity, GHQ caseness was predictive of stroke during 0 to 5 years of follow-up (HR=1.6; 95% CI, 1.13-2.26), but not during 5 to 10 years (HR=0.94; 95% CI, 0.64-1.37). A dose-response relationship was established between cumulative GHQ caseness and incident CHD during the final 5-year observation cycle (HR=1.12; 95% CI, 0.72-1.74 for one to two incidences of caseness; HR=2.06; 95% CI, 1.15-3.69 for three to four incidences), but not between GHQ caseness and stroke (HR=0.48; 95% CI, 0.26-0.89 for one to two incidences; HR=0.76; 95% CI, 0.3-1.94 for three or four incidences). The researchers also wrote that CES-D caseness was predictive of CHD (HR=1.81; 95% CI, 1.07-3.06), but not stroke.
“There was evidence of a dose-response effect in the prospective association between depressive disorder and major CHD, and this association did not appear to be subject to reverse causation,” the researchers concluded. “… Analysis of further cohort data suitable for study of reverse causation and dose-response effects will help to resolve the uncertainties about depression as a causal factor in CHD and stroke.”
Disclosure: The researchers report no relevant financial disclosures.