Low Levels of 'Feel Good' Neurosteroid Found in Both Obese and Anorexic Women
등록일 2019년 01월 07일 토요일
수정일 2017년 11월 18일 토요일

Photo by: Courtney Emery via Flickr

Eating disorders are complex, severe conditions that affect both the emotional and physical health of an individual.These conditions are life-threatening and lead to productivity, health and emotional consequences, even resulting in death.Anorexia is the condition where a body is denied the required essentials to function perfectly while obesity is the condition that results in excessive fat in the body leading to health problems.Both of these conditions have resulted in adverse effects on the body.In a recent research, women with these extreme weight spectrums have been found to have low levels of the neuroactive steroid allopregnanolone.

In previous research carried out, low levels of allopregnanolone were associated with depression and anxiety which are both mood disorders linked to obesity and anorexia nervosa.

Allopregnanolone, commonly known as 'allo' to a scientist, is a metabolite of the hormone progesterone which is one of the primary female hormones.  This metabolite is known to bind receptors for the neurotransmitter gamma-aminobutyric acid in the brain.These receptors are also known to be the targets of some anti-anxiety drugs like benzodiazepines.Allopregnanolone works by improving the signal produced when GABA binds to its receptor which is responsible for producing feelings of well-being and a positive mood.

Statistics show that more than 43 percent of adults battling obesity have depression while over 50 percent of women with anorexia nervosa have anxiety or depression.Despite associating low levels of allo with anxiety and depression in previous studies, the impact of allo on mood has not been measured in obese and anorexic women.

According to Graziano Pinna, an associate professor of psychiatry in the University of Illinois at Chicago College of Medicine and an author on the study, more evidence on the association between low allo levels and anxiety, depression, post-traumatic stress disorder, and other mood disorders has been realized.Pinna further adds that the evidence of obese and anorexic women having low levels of allo shows that the role of allo is under-recognized in mood disorders.

Researchers in this study led by Dr.Karen Miller, professor of medicine at Harvard Medical School, engaged 12 women with amenorrhea (stopped having their menstrual periods) and anorexia nervosa whose body mass indices were less than 18.5. 12 obese women with a BMI at 25 or higher; and 12 women with normal weight with BMIs between 19 and 24.None of these women was on anti-depressants or had a previous history of depression diagnosis.The average age of all the women participants was 26 years old.

The participants filled questionnaires to assess for anxiety and depression, and blood samples were collected from them.All the blood measurements of allo and other hormones were carried out at Pinna's lab at the UIC.Pinna's lab had previously established a unique highly-sensitive method to detect sex hormones and their metabolites.It is among three other labs in the United States that perform these measurements that use gas chromatography and mass spectrometry to detect minimal levels of these chemicals in saliva, brain tissue, and blood serum.

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The findings showed that in obese women and those with anorexia nervosa, the blood levels of allo were 50 percent lower than in women who had normal BMI.In addition, women who were clinically obese had allo levels approximately 60 percent lower than those with normal weight.

The research also revealed that allo levels in all participants correlated with the severity of their anxiety and depression symptoms as previously measured in the questionnaires.Those women with the lowest levels of allo had more extreme depression symptoms.

Levels of progesterone were equally low across all the participants, indicating that the decreases of allo in these women with obesity and anorexia nervosa may have been caused by improper functioning of enzymes responsible for the metabolism of progesterone into allo.

Participants with anorexia nervosa had low progesterone because they had a history of amenorrhea, and the other two categories had low progesterone levels because their blood had been taken in the follicular phase when this hormone is naturally low.Pinna said that with the findings of lower levels of allo in obese women than in those with normal weight, it is evident that allo is involved in anxiety and depression despite the amount of progesterone available.

This study indicates that the enzymes which converts progesterone into allo may not be working properly, which leads to decreases in allo resulting in mood disorders.Pinna says that drugs may be useful to boost the allo levels by increasing the efficacy of these enzymes.He further adds that more research is needed to establish the deficit in the metabolism of progesterone into the allo so that precision medicines using allo as a biomarker can be established.

Depression has become an increasing problem among women today, especially those in the extremes of the weight spectrum.This study seeks to create hope by creating a greater understanding of mechanisms leading to these disorders, including abnormalities in hormones regulation and their neuroactive metabolites.This may lead to new targeted therapies in the end.

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