Obesity increases risk of mental disorders throughout life

"We analyzed a population-wide national registry of inpatient hospitalizations in Austria from 1997 to 2014 in order to determine the relative risks of comorbidities in obesity and identify statistically significant sex differences," explains Elma Dervic of the Complexity Science Hub. Consequently, it became evident that an obesity diagnosis significantly enhances the likelihood of a wide range of mental disorders across all age groups -- including depression, nicotine addiction, psychosis, anxiety, eating and personality disorders. "From a clinical point of view, these results emphasise the need to raise awareness of psychiatric diagnoses in obese patients and, if necessary, to consult specialists at an early stage of diagnosis," says Michael Leutner of the Medical University of Vienna.

FIRST DIAGNOSIS: OBESITY

"In order to find out which illness typically appeared prior and subsequently to the obesity diagnosis, we had to develop a new method," explains Dervic. This allowed the researchers to determine if there were trends and typical patterns in disease occurrence.

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 considered psychopharmacological medications to cause the association between mental disorders and obesity as well as diabetes. This may be true for schizophrenia, where we see the opposite time order, but our data does not support this for depression or other psychiatric diagnoses," explains Alexander Kautzky from Department of Psychiatry and Psychotherapy of the Medical University Vienna. However, whether obesity directly affects mental health or whether early stages of psychiatric disorders are inadequately recognised is not yet known.

GREATER IMPACT IN 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 obese men also suffer from nicotine abuse disorder, 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 twice as likely to be affected (6.61% obese; 3.21% non-obese).

COUNTERACT AT A YOUNG AGE

At present, obesity is a highly prevalent disease worldwide and affects more than 670 million people. The fact that the disease promotes metabolic disorders and serious cardio-metabolic complications (diabetes mellitus, arterial hypertension, and dyslipidaemia) has already been extensively researched.

Since this study now also shows that obesity often precedes severe mental disorders, the findings underscore its importance as a pleiotropic risk factor for health problems of all kinds. 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.