Inverse association between changes in systolic and diastolic blood pressure and risk of depression: A nationally representative cohort study.

Background: Depression is one of complex mental disorders with diverse etiological factors but the association between blood pressure (BP) and depression is unknown. We aimed to investigate the association between changes in BP (systolic and diastolic) and incident depression.

Methods: From the National Health Insurance Service-Health Screening Cohort (NHIS-HEALS), 224,192 participants who underwent biennial health screenings from period I (2004-05) and II (2006-07) were included in the study. Systolic BP (SBP) and diastolic BP (DBP) categories were defined as follows: SBP into 5 categories (<90 mmHg, 90 mmHg -119 mmHg, 120 mmHg -129 mmHg, 130 mmHg -139 mmHg, ≥140 mmHg) and DBP into 4 categories (<60 mmHg, 60 mmHg -79 mmHg, 80 mmHg -89 mmHg, ≥90 mmHg). Also, BP levels were classified into 5 groups: normal, elevated BP, stage 1 BP, stage 2 BP, hypotension. Using the Cox proportional hazards regression, changes in SBP and DBP between two screening periods and the risk of depression were calculated by adjusted hazard ratio (aHR) and 95 % confidence interval (CI).

Results: There were 17,780 depression events during 1.5 million person-year of follow-up. Compared to the participants with SBP ≥ 140 mmHg or DBP ≥ 90 mmHg from both periods, those who decreased SBP from ≥140 mmHg to 120 mmHg-129 mmHg (aHR 1.13; 95 % CI 1.04-1.24; P = 0.001) and those who decreased DBP from ≥90 mmHg to 60 mmHg-79 mmHg (aHR 1.10; 95 % CI 1.02-1.20; P = 0.020) showed a higher risk of depression, respectively.

Conclusions: Changes in SBP and DBP showed an inverse relationship with depression risk.