Insulin resistance linked to current, but not remitted, MDD

Insulin resistance appeared associated with current major depressive disorder but not with remitted MDD, according to study results published in JAMA Psychiatry.

These findings suggested insulin resistance is a state, rather than trait, depression biomarker, researchers noted.

“Characterization of these associations represents a critical step at better phenotyping, a prelude to longitudinal studies and a more targeted approach to the treatment of MDD,” Kathleen T. Watson, PhD, of the department of epidemiology and population health at

Stanford School of Medicine in California, and colleagues wrote. “We investigated whether [insulin resistance] was positively associated with the presence of major depression, the severity of major depression and the chronicity of major depression using the Netherlands Study of Depression and Anxiety (NESDA).”

The investigators analyzed data of 1,268 NESDA participants who had proteomic data and were categorized into three groups, which were current MDD, remitted MDD and those with no history of the disorder who served as controls. They used two well-validated insulin resistance biomarkers, the quantitative insulin sensitivity check index (QUICKI) and the triglyceride to high-density lipoprotein (HDL) ratio, to attempt to evaluate whether use of different surrogate insulin resistance measures had consistent links to MDD.

Participants with insulin resistance were older, had less education and had higher BMI vs. those who were insulin sensitive. Watson and colleagues reported an association between insulin resistance and current MDD compared with controls (OR = 1.51; 95% CI, 1.08-2.12), but not with remitted MDD (OR = 1.14; 95% CI, 0.79-1.64). Both insulin resistance measures were positively associated with depression severity among those with current MDD. Triglyceride-HDL, but not the QUICKI, was associated with depression chronicity. Participants with remitted MDD exhibited no associations between insulin resistance and depression severity nor chronicity. After adjustment for antidepressant use, the researchers observed no substantial changes in model outcomes.

“Taken together, these biomarkers of metabolic dysfunction represent simple, clinically accessible methods of identification of [insulin resistance] among currently depressed patients,” Watson and colleagues wrote. “One limitation of this analysis was the cross-sectional design. Longitudinal analyses need to extend these findings and examine temporality and are the subject of our current investigations.”