Results from a recent study published in the journal Neuropsychiatric Disease and Treatment confirmed previous knowledge that the relationship between common mental symptoms and leptin is modulated by obesity in severely obese patients.
Depressive and anxiety disorders are highly prevalent worldwide. Body mass index (BMI) is used to classify underweight, overweight, and obesity. Obesity is defined by the WHO as BMI >30 kg/m. Obesity leads to several chronic diseases such as diabetes, hypertension, cardiovascular events, hyperlipidemia, and stroke. Evidence has also shown an association between obesity and psychiatric comorbidities.
Adipose tissue secretes large amounts of proinflammatory cytokines. Hypercytokinemia, from a chronic inflammatory state of obesity, has been found to be associated with depressive symptoms. Studies have also indicated that leptin has its role in the association between obesity and psychiatric comorbidity.
Leptin, the “satiety hormone,” is a hormone made by adipose cells that helps to regulate energy balance by inhibiting hunger. It is associated with the sensation of “feeling full.”
To explore the association among leptin levels, adiposity, psychiatric symptoms, and their interaction in bariatric surgery candidates, a team of researchers led by Yung-Chieh Yen from the Department of Psychiatry, E-Da Hospital in Kaohsiung, Taiwan, measured the serum leptin levels and body mass index (BMI) in 39 obese participants. All participants were assessed with The Chinese Health Questionnaire and Taiwanese Depression Questionnaire.
Results revealed that the mean BMI was 39.4 kg/m2 (±6.8), and the mean leptin level was 24.5 ng/mL (±9.4). Results derived from the multivariate analysis revealed that the Chinese Health Questionnaire-by-BMI and Taiwanese Depression Questionnaire-by-BMI interaction terms were predictors of leptin level. The results also showed that female patients had significantly higher leptin levels compared with male patients. This is significant because it is believed that in obesity, a decreased sensitivity to leptin occurs, resulting in an inability to detect satiety despite high energy stores.
The researchers concluded that some of the study findings validate the results of previous studies and have shown the importance of interactive effects among depression, anxiety, and obesity relative to leptin in psychoendocrinology, even in obese patients
The researchers suggest that future studies should focus on further measures of leptin receptors or signaling on the basis of these interactive effects in psychiatry.