Depressive symptom clusters as predictors of 6-year increases in insulin resistance: data from the Pittsburgh Healthy Heart Project.
OBJECTIVE
To examine longitudinal bidirectional associations between two depressive symptom clusters-the cognitive-affective and somatic-vegetative clusters--and insulin resistance, a marker of prediabetes.


METHODS
Participants were 269 adults aged 50 to 70 years without diabetes enrolled in the Pittsburgh Healthy Heart Project, a prospective cohort study. At baseline and 6-year visits, participants completed the Beck Depression Inventory-II (BDI-II) and underwent a blood draw to quantify fasting insulin and glucose. We examined baseline BDI-II total, cognitive-affective, and somatic-vegetative scores as predictors of 6-year change in the homeostatic model of assessment (HOMA) score, an estimate of insulin resistance computed from fasting insulin and glucose. We also examined baseline HOMA score as a predictor of 6-year change in BDI-II total and subscale scores.


RESULTS
Regression analyses, adjusted for demographic factors and baseline HOMA score, revealed that the baseline BDI-II somatic-vegetative score (β = 0.14, p = .025), but not the cognitive-affective (β = 0.001, p = .98) or total (β = 0.10, p = .11) scores, predicted 6-year HOMA change. This result persisted in models controlling for anxiety symptoms and hostility. Several factors were examined as candidate mediators; however, only change in body mass index was a significant mediator (p = .042), accounting for 23% of the observed association. Baseline HOMA score did not predict 6-year change in BDI-II total or subscale scores (all p values >.56).


CONCLUSIONS
Among adults aged 50 to 70 years, the somatic-vegetative symptoms of depression (e.g., fatigue, sleep disturbance, and appetite changes) may worsen insulin resistance and increase diabetes risk, partly, by increasing body mass index.
Department of Psychology (T.K., J.C.S.), Indiana University-Purdue University Indianapolis (IUPUI), Indianapolis, Indiana; Heart & Vascular Institute (M.F.M), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and Department of Psychology (T.W.K.), University of Pittsburgh, Pittsburgh, Pennsylvania.
Tasneem
T
Khambaty
Jesse C
JC
Stewart
Matthew F
MF
Muldoon
Thomas W
TW
Kamarck
D000368:Aged; D000428:Alcohol Drinking / Q000453:epidemiology; D001007:Anxiety / Q000453:epidemiology; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000032:analysis; D003863:Depression / Q000453:epidemiology*; D003924:Diabetes Mellitus, Type 2 / Q000453:epidemiology; D005221:Fatigue / Q000453:epidemiology; D001068:Feeding and Eating Disorders / Q000453:epidemiology; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D009765:Obesity / Q000453:epidemiology; D011446:Prospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D012893:Sleep Wake Disorders / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology; D012959:Socioeconomic Factors
C508600:IL6 protein, human; D015850:Interleukin-6; D002097:C-Reactive Protein