Comparison of the level of allostatic load between patients with major depression and the general population

We compared the level of allostatic load (AL) between patients with major depressive disorder (MDD) and non-depressed controls using two definitions of AL: continuous AL scores (AL index) and clinically significant high AL (≥4). We examined whether MDD was associated with AL independent of basic socioeconomic (age, sex, cohabiting status and level of education) and lifestyle factors (smoking and alcohol use).

The MDD patient sample consisted of 177 psychiatric outpatients (mean age 33.7, SD 10.7 years), who were recruited from the Department of Psychiatry at Kuopio University Hospital, Finland, in 2016-19. The non-depressed controls (n = 228, mean age 49.8, SD 10.1 years) lived in the municipality of Lapinlahti, Finland. Ten biomarkers were used to construct the two AL variables. These indicators were systolic and diastolic blood pressure, total cholesterol, high-density lipoprotein (HDL) cholesterol, triglycerides, glucose, creatinine, waist circumference, body mass index (BMI) and C-reactive protein (CRP).

The mean AL scores did not significantly differ between MDD patients (2.97) and non-depressed controls (3.12), thus it was not associated with MDD in univariate analysis. In multivariate models a higher AL index was associated with a 1.42 to 1.82 times higher likelihood of belonging to the MDD group. Furthermore, we found that high AL (i.e. AL ≥ 4) was associated with MDD, with the likelihood ranging between 2.27 and 2.96 compared with the non-depressed controls in multivariate models.

Even young adult patients with MDD appear to display clinically significant, high AL compared with non-depressed controls. Thus, it is important to pay attention to the somatic health of depressed patients in addition to their mental health.