Food for thought? Prevalence of mental health disorders driven by obesity, experts flag

31 May 2023 --- The risk of developing mental disorders increases with obesity, according to scientists at the Complexity Science Hub and the Medical University of Vienna, Austria. The study found that this goes for all age groups and that obese women are at higher risk for most disorders, except schizophrenia and nicotine addiction, compared to obese men. 

NutritionInsight speaks with two co-authors of the study from the Medical University Vienna, Austria – Alexander Kautzky, a scientist at the Department of Psychiatry and Psychotherapy and Michael Leutner, a consultant at the Department of Medicine III – Division of Endocrinology and Metabolism.

“Sex differences in the prevalence of psychiatric disorders are well-known but are further boosted in the presence of obesity, as shown in the current study. Several factors may contribute to female overrepresentation in mental health disorders, including biological factors such as differences in sex hormones and immune response,” says Kautzky.

“Psychosocial risk factors for women include higher risk of adverse and traumatic life events, socioeconomic marginalization and dysfunctional gender roles leading to stress. All these factors are impacted by obesity.”

“Despite often leading to discrimination in everyday life, obesity is often not fully recognized as a severe disorder in health care settings,” Leutner tells us.

It is still unknown whether obesity directly affects mental health or whether the early stages of psychiatric disorders are inadequately recognized.Diagnoses and obesity
To determine typical patterns, the researcher developed a new method to find which illness occurred before and after the participants were diagnosed with obesity.

Published in Translational Psychiatry, the study evidenced that obesity increases the risk of depression, nicotine addiction, psychosis, anxiety, personality and eating disorders. The scientists analyzed a population-wide national registry of inpatient hospitalizations in Austria from 1997 to 2014.

They found that, except for the spectrum of psychosis, obesity was the first diagnosis of all co-diagnoses.

“Until now, physicians often considered psychopharmacological medications to cause the association between mental disorders and obesity and 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,” says Kautzky.

However, it is still unknown whether obesity directly affects mental health or whether the early stages of psychiatric disorders are inadequately recognized.

Depression among obese women was three times higher than in non-obese women, 13.3% compared to 4.8%. 

The scientists further say obesity affects 670 million people worldwide, and its implications on metabolic disorders and cardio-metabolic complications such as diabetes and hypertension have already been studied extensively. Still, its impact on mental health conditions is “urgently needed,” they stress.

The gut microbiome
The researchers did not study the gut microbiome, but Kautzky explains that earlier findings point toward a role of nutrition and gut microbiota in obesity and mental health. 

“Psychological and cell stress are well-known negative moderators of gut microbiota, shifting toward unfavorable bacterial composition. Furthermore, unhealthy diets such as high fat intake that is common in mental health and metabolic disorders negatively impact the gut microbiota and mental health.”

He further notes that the gut microbiome was suggested to mediate autoimmune disorders in dependence on gender. On a speculative note, the higher risk for mental health disorders in women than in men with obesity may be linked to the gut microbiota, but further research is needed.

A recent French study found a link between toddlers’ gut microbiota and a prediction of child obesity. It evidenced that the bacteria Firmicutes and Bacteroidetes are directly involved with obesity, as individuals with more Bacteroidetes were shown to be leaner.

Meanwhile, a US-based study found a link between suppressing emotions and gut health among women. China-based research found an increased risk of Crohn’s disease – a chronic inflammatory bowel disease – when following a Western diet.

Brain healthGovernments should implement better preventive and early counteracting measures, says Leutner.
Kautzky explains that as obesity is among the most prevalent disorders worldwide, which often affects people from an early age, the link to a broad spectrum of mental health disorders is crucial for public mental health. 

“While mental health disorders are often difficult to diagnose in primary health care settings correctly, obesity can easily be recognized and diagnosed. Guidelines for managing psychiatric disorders such as depression, bipolar disorder and schizophrenia have already adopted the link to obesity and diabetes. However, most focus on monitoring drug side effects.”

“On the other hand, guidelines for obesity currently do not reflect the need to pay special attention to psychiatric comorbidities, except for high-risk cohorts such as patients eligible for bariatric surgery. Our study indicated that public health should aim at a higher sensitivity for ill mental health in all patients with obesity,” Kautzky concludes. 

Leutner adds that governments should implement better preventive and early counteracting measures, such as programs starting from an early age that strengthen healthy physical activity and give dietary counseling. 

“Dietary interventions often bear less risk of side effects than pharmacological treatment options and are in control of patients, therefore also representing a chance of patient empowerment. We would wish to see the food industry taking on this responsibility.” 

“It is necessary that there is a close cooperation and interdisciplinary approach between endocrinologists and specialists for psychiatry, especially in obese patients who have clinical symptoms of mental disorders. In general, a higher awareness in the clinical practice for mental disorders in patients with obesity is necessary,” Leutner underscores.

By Beatrice Wihlander

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