March 2011
Reviewer: Jeff C. Huffman, MD
Psychological distress predicts the development of the metabolic syndrome: a prospective population-based study
Puustinen PJ, Koponen H, Kautiainen H, et al
Psychosom Med 2011;73(2):158-165
Background: Metabolic syndrome (MetS), a constellation of abnormalities in blood pressure, lipids, waist circumference and blood sugar, is an increasingly prevalent condition that is associated with the development of cardiovascular disease and with all-cause mortality. There has been relatively limited study of the connection between psychological distress and the subsequent development of MetS, though there have been studies linking depression with MetS.
Methods: This was a prospective study of subjects aged 36-56 years sampled from a town in Eastern Finland. Overall there were 1294 persons identified; those who did not have MetS at baseline, and who completed a baseline (1997/1998) and 7 year follow-up visit, were included. Assessments included laboratory evaluations for MetS markers and clinical assessments of medical health, sociodemographic characteristics, and psychological distress as measured by the General Health Questionnaire-12 (GHQ-12; the authors used a cutoff of 4 or greater to define distress) and the Beck Depression Inventory (BDI).
Results: A total of 466 subjects (281 women) met study criteria; 86 (18%) met criteria for elevated psychological distress on the GHQ-12. Subjects with elevated distress were more slightly older, more likely to be unmarried, less likely to have leisure time characterized by frequent physical activity, and had substantially higher BDI scores (11.8 vs. 2.6); there were no other significant between-group differences on baseline characteristics. Over a mean 6.4 year follow-up period, 101 (22%) subjects developed MetS. There was a linear trend between GHQ-12 scores and risk of MetS, with risk increasing by 10% with every GHQ-12 point. Mean GHQ-12 scores of those who did and did not develop MetS were significantly different (2.4 vs. 1.5; p=.010). On multivariate logistic regression that included age, gender, marital status, smoking, physical activity, education, alcohol use, and hsCRP, GHQ-12 remained significantly associated with MetS development.
Commentary: Given the increasing attention to, and escalating incidence of, metabolic syndrome, assessing the impact of psychological distress on the development of this condition is important. This study has several strengths: it was a relatively large prospective study that controlled for multiple important potential confounding variables. If general psychological distress is linked to metabolic syndrome, this suggests that it is important to manage more than just depression when assessing risk for metabolic syndrome or understanding potential psychologically-mediated mechanisms for its development.
However, the main concern regarding this study is that one wonders if the GHQ-12 score here was actually a marker for depression rather than more general psychological distress. Indeed, those patients with high distress had substantially higher BDI scores, and BDI and GHQ-12 scores were strongly correlated with one another in the study. The authors point out that a prior analysis of this study cohort looked at BDI scores and the risk of metabolic syndrome, and found that depression was linked with MetS only in women in that analysis, while GHQ-12 was linked with MetS in both genders here. They also note that the GHQ-12 measures anxiety and perceived stress, which are not meaningfully measured by the BDI.
In the end, when combining this report with extant literature, the take home message regarding psychological risk factors for MetS is probably the same for that of psychological risk factors for many medical illnesses, especially cardiovascular illnesses: depression is probably the strongest risk factor for the development and progression of disease, while other factors like anxiety and perceived stress are also important to consider and manage.