Study finds obesity increases risk of mental disorders

People suffering from obesity are at a significantly greater risk of also developing mental disorders. This applies to all age groups, whereby women are more at risk than men for most diseases, as a recent study by the Medical University of Vienna and the Complexity Science Hub Vienna shows. The results were published in the journal Translational Psychiatry.

In the context of this study, the research team analyzed a population-based dataset of all inpatient hospitalizations in Austria from 1997 to 2014 in order to determine the relative risks of concomitant diseases in obesity and to identify statistically significant gender differences. Consequently, it became evident that an obesity diagnosis significantly increases the probability of a broad spectrum of mental disorders in all age groups—including depression, nicotine addiction, psychosis, anxiety, eating and personality disorders.

"From a clinical point of view, these results emphasize the need to raise awareness of psychiatric diagnoses in obese patients and, if necessary, to consult specialists at an early stage of diagnosis," explains study leader Michael Leutner from the Department of Internal Medicine II at MedUni Vienna.

Obesity as the first diagnosis

"In order to find out which illness typically appeared prior and subsequently to the obesity diagnosis, we had to develop a new method. This allowed us to determine whether there are trends and typical patterns in the occurrence of diseases," explains co-first author Elma Dervic from the Complexity Science Hub. "In case of all co-diagnoses, with the exception of the psychosis spectrum, obesity was in all likelihood the first diagnosis made prior to the manifestation of a psychiatric diagnosis. "

Until now, physicians often assumed that psychopharmacological drugs were the cause for the link between mental disorders and diabetes.

"This may be true for schizophrenia, where we see the reverse chronological order, but our data does not support this for depression or other psychiatric diagnoses," explains first author Alexander Kautzky from the Department of Psychiatry and Psychotherapy at MedUni Vienna. However, whether obesity directly affects mental health or whether early stages of psychiatric disorders are inadequately recognized is not yet known.

Greater impact on women

Surprisingly, the researchers found significant gender differences for most disorders—with women showing an increased risk for all disorders except schizophrenia and nicotine addiction. While 16.66% of all obese men also suffer from nicotine addiction, this is only the case in up to 8.58% of obese women.

The opposite is true for depression. The rate of diagnosed depressive episodes was almost three times higher in obese women (13.3 % obese; 4.8 % non-obese). Obese men were affected twice as often (6.61 % obese; 3.21 % non-obese).

Screening for mental health problems needed

Obesity affects more than 670 million people worldwide. The fact that the disease promotes metabolic disorders and serious cardio-metabolic complications (diabetes mellitus, arterial hypertension and dyslipidemia) has already been extensively researched.

The fact that, according to the current study, obesity often precedes severe mental disorders emphasizes its importance as a risk factor for health problems of all children. This is primarily true for young age groups, where the risk is most pronounced. For this reason, thorough screening for mental health problems in obese patients is urgently needed to facilitate prevention or ensure that appropriate treatment can be given, so the researchers conclude.