Studies Explain Why Women Are More Prone to Depression
Researchers examined the brains of 115 participants and found that an inflammation called anhedonia can lead to loss of pleasure in women, but not men.
Depression, the “worldwide cause of disability,” is much more common in women than in men. More than 300 million people worldwide experience depression.
Among young people between the ages of 14 and 25, women are more than twice as likely to experience depression as men. Although these differences become less pronounced in later adulthood, global estimates still show a 1.7-fold increase in the prevalence of depression in women compared with men.
Anhedonia is one of the most important features of major depressive disorder. Anhedonia causes a lack of joy or pleasure in activities that previously felt enjoyable.
At the neurological level, anhedonia presents itself as reduced activity in the reward processing area of the brain called the ventral striatum.
New research sheds light on how gender differences in depression manifest in the brain. Specifically, the scientists show how inflammation affects the brain’s response to different rewards in men and women.
Naomi Eisenberger, Professor at the University of California, Los Angeles, is the senior author of the paper appearing in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging.
Anhedonia in Response to Inflammations
Eisenberger and colleagues administered a low dose of an endotoxin to induce inflammation—or a placebo effect for men and women who aren’t depressed.
There were a total of 115 participants, 69 of whom were women. Researchers randomly assigned participants to either the control/placebo group or the low-dose endotoxin group.
Two hours after the intervention, the peak of the intervention’s reaction to the toxin peak, participants were asked to complete a task in which they had to wait for a monetary reward. Participants performed the task inside the MRI scanner.
The results revealed that endotoxin reduced the activity of the ventral striatum that underwent reward processing. However, researchers noticed that this effect differed by gender.
“Specifically,” Prof. Eisenberger et al., “In female participants, endotoxin (vs placebo) anticipation of reward [ventral striatum] caused a decrease in activity, but this effect was absent in male participants.”
Furthermore, these decreases in the activity of the ventral striatum were “associated with increased inflammation in women, but not in male participants.”
First author Mona Moieni, Ph.D. “This suggests that women with chronic inflammatory disorders may be particularly vulnerable to developing depression with reduced sensitivity to reward,” she says.
“Clinicians treating female patients with inflammatory disorders may want to pay close attention to these patients for the possible onset of depressive symptoms,” says Moieni.
“Our study is the first to show that there are sex differences in neural sensitivity to reward in response to inflammation, which has important implications,” Eisenberger said.
“[Bulgular] It can cause women to experience a much higher rate of depression than men, especially for the types of depression that can be inflammatory in nature.” Naomi Eisenberger, Ph.D.
The editor of Biological Psychiatry, Dr. Cameron Carter: Cognitive Neuroscience and Neuroimaging also comments on the significance of the study.
He said it “highlights the important gender differences that exist in the human brain and proposes a mechanism that may help explain why depression is more common in women compared to men.”
Medical News Today, Brain study may explain why depression is more common in women, 2019.