Why obesity, underweight condition may up depression in women

Women who are extremely underweight and obese are likely to be at an increased risk of developing common mood disorders like depression and anxiety, as a result of low feel good neuroactive steroid, finds a study.

Neurosteroid "Allopregnanolone" also known as "allo" is a metabolite of the hormone progesterone -- a female hormone. 

Allo works by producing a positive mood and feelings of well-being. 

The findings showed that in women with anorexia nervosa, blood levels of allo were 50 per cent lower than they were in women with normal body mass index (BMIs). 

Women who were clinically obese had allo levels approximately 60 per cent lower than women with normal weights. 

Further, participants with lower levels of allo had greater severity of depression symptoms, the researchers noted. 

"Depression is an incredibly prevalent problem, especially in women, and also particularly at the extremes of the weight spectrum," said Karen Miller, professor at Harvard Medical School. 

"We are beginning to see more and more evidence that low allo levels are tightly linked to depression, anxiety, post-traumatic stress disorder and other mood disorders," added Graziano Pinna, associate professor in the University of Illinois at Chicago. 

In addition, progesterone levels were similarly low across both groups, suggesting that the decrease in allo in these participants may have been caused by improper functioning of enzymes.

The enzymes that convert progesterone into allo may not be working properly, causing decreases in allo that lead to mood disorders. 

For the study, published in the journal Neuropsychopharmacology, the team recruited women with anorexia nervosa and amenorrhea (whose menstrual periods have stopped) whose body mass indices were less than 18.5, normal-weight women with BMIs between 19 and 24, and obese women with BMIs at 25 or higher. 

"Drugs that increase the efficacy of these enzymes may be useful in helping to boost allo levels," Pinna said. 

"The hope is that a greater understanding of mechanisms contributing to these disorders -- including abnormalities in the regulation of hormones and their neuroactive metabolites -- may lead to new targeted therapies in the future," Miller noted.