Obesity linked to poorer outcomes in people with bipolar disorders

Reviewed by Danielle Ellis, B.Sc.Sep 20 2023

The obesity pandemic is particularly hard on people with bipolar disorders. This has been shown in a study conducted at the University of Gothenburg. The results suggest that the group of adults with bipolar disorders will fall behind in life expectancy compared with the general population.

It is already known that adults with bipolar disorders are also more prone to obesity. The current study, published in the American Journal of Psychiatry, highlights the extent and rate at which the group is affected by the obesity pandemic.

The researchers examined BMI progression during a 12-year period, 2008-2019, in a sample of 22,127 individuals with bipolar disorders and 71,894 individuals from the general population in Sweden. Data were obtained from the national quality register BipoläR and the national surveys of living conditions by Statistics Sweden (SCB).

The proportion of obesity in the general population increased from 11% to 15% among men and from 10% to 13% among women during that period. In the group with bipolar disorders, the proportion of obesity increased from 22 to 29% among men and from 25 to 33% among women.

Less response to medicines

Bipolar disorders are found in two to three percent of the population and are characterized by periods of mania and depression. Without treatment, the disorder is often serious and disabling, but with the support of medication and educational and psychological treatment, most people can live a normal life.

However, the researchers warn about the consequences of the large increases and high levels of obesity in bipolar disorders. This concerns not only a poorer prognosis of cardiovascular disease, osteoarthritis, asthma, several forms of cancer and the risk of failed antibiotic treatment.

First author of the study, Hemen Najar, is a Senior specialist at the Department of Psychotic Disorders at Sahlgrenska University Hospital, and has a PhD in psychiatry and neurochemistry from Sahlgrenska Academy at the University of Gothenburg:

"In addition to the general negative effects, obesity has also been linked to a poorer response to antidepressants and to treatment with lithium and valproate in individuals with bipolar disorders. Obesity also aggravates the overall prognosis of bipolar disorders by increasing the likelihood of relapse and the severity of episodes with oscillating mood," he says.

Risk of trend reversal in mortality

The study shows how quickly BMI increases in the group with bipolar disorders compared with the general population. The increase per decade was 0.4 units for men and 0.6 for women in the general population, compared with 1.1 units for men and 1.4 for women with bipolar disorders.The widening BMI gap has consequences, according to the researchers. The combination of bipolar disorders and obesity is a co-morbidity that affects individuals and increases the risk of premature death in the group with bipolar disorders.

In fact, the health consequences of increasing obesity can reverse the decline in premature mortality and comorbidity observed over the last four decades. Women with bipolar disorders and those with the highest BMI are the most affected individuals."

Hemen Najar, Senior Specialist, Department of Psychotic Disorders, Sahlgrenska University Hospital