New study finds that insulin resistance doubles the risk of depression

"If you have insulin resistance, your risk of major depression is twice that of people without insulin resistance, even if you have never experienced depression before," said Natalie Rasgon, MD, professor of psychiatry and behavioral sciences

More than one in five Americans has experienced severe depression in their lives

The researchers' findings were published in the September 22 issue of the American Journal of Psychiatry

A common but silent state

Studies have confirmed that at least one-third of us have insulin resistance, and often don’t know it

Insulin’s job is to tell our cells that it’s time to process the glucose in our blood, which is produced in our liver or both due to our dietary intake

The link between insulin resistance and some mental disorders has been confirmed

But these assessments are based on cross-sectional studies, that is, a snapshot of the population at a certain point in time

As part of the multi-agency collaboration of the research network established by Rasgon in 2015, the scientists obtained data from an ongoing longitudinal study that carefully monitored more than 3,000 participants to understand the causes and causes of depression.

Watson said: "This Dutch study has conducted careful monitoring of a large group of subjects for 9 years, and it is still rising.

Determine insulin resistance

The Stanford University research team analyzed the data of 601 men and women who were the control group of the Dutch study

The research team measured three indicators of insulin resistance: fasting blood glucose levels, waist circumference, and the ratio of circulating triglyceride levels to circulating high-density lipoprotein (HDL) levels

They studied the data to determine whether subjects with insulin resistance had a higher risk of major depression within 9 years

Watson said: "Some of the study subjects already had insulin resistance at the beginning of the study-there is no way to know when they started to develop insulin resistance

Therefore, the researchers limited the next phase of the analysis to about 400 subjects who had never experienced severe depression and showed no signs of insulin resistance at the beginning of the study

Although the number of participants is too small to establish a statistically significant waist circumference and triglyceride-to-HDL ratio, the results of fasting blood glucose are not only statistically significant, which means that there is no chance, but it is clinically meaningful - that is , Important enough to worry: Those who developed prediabetes in the first two years of the study, at the 9-year follow-up milestone, the risk of major depression was 2.

The bottom line is: Insulin resistance is a strong risk factor for serious problems, including not only type 2 diabetes but also depression

"By assessing the mood of patients with metabolic diseases (such as obesity and high blood pressure), it is time for doctors to consider the metabolic status of those with mood disorders, and vice versa," Rasgon said
.
"To prevent depression, doctors should check the patient's insulin sensitivity
.
These tests are easily available in laboratories around the world, and they are not expensive
.
Ultimately, we can slow the development of debilitating lifelong diseases
.
"

Rasgon is a member of the Wu Tsai Neuroscience Institute at Stanford University, the Stanford Cardiovascular Institute, and the Stanford Institute for Maternal and Child Health
.

Other research co-authors at Stanford University include Lacey Nutkiewicz, former clinical research coordinator; Julia Simard, PhD, associate professor of epidemiology and population health; and professor of epidemiology, population health, neurology, and neuroscience Victor Henderson, MD
.

Other researchers from Amsterdam University Medical Center and a researcher from Rockefeller University also participated in this work
.

The research was partly funded by the Pritzker Neuropsychiatric Disorder Research Association
.

Journal Reference :

1. Kathleen T.
   Watson, Julia F.
   Simard, Victor W.
   Henderson, Lexi Nutkiewicz, Femke Lamers, Carla Nasca, Natalie Rasgon, Brenda WJH Penninx.
   Incident Major Depressive Disorder Predicted by Three Measures of Insulin Resistance: A Dutch Cohort Study .
   American Journal of Psychiatry , 2021; appi.
   ajp.
   2021.
   2 DOI: 10.
   1176/appi.
   ajp.
   2021.
   20101479