Obesity is associated with risk of depression in the elderly

A new study in PLOS ONE discusses the relationship between depression and obesity.

Study: Associations between obesity measures and depression and well-being scores: A cross-sectional analysis of middle-aged to older adults. Image credit: Creative Images / Shutterstock.com

Obesity and depression

Previous research suggests a close relationship between obesity and depression, with obesity reported in nearly 60% of people in a group with severe depression. This study also showed that obesity was 1.2-1.5 times more likely in people with major depression. However, conflicting results regarding this association have been reported in other studies.

A healthy lifestyle is associated with mental health benefits, while an unhealthy lifestyle has been shown to increase the risk of depression. This is important as lifestyle factors can be modified to reduce the risk of poor mental health.

The present study sought to generate consistent and reproducible data using two different measures of fat mass or obesity to assess the association with mental health. More specifically, both body mass index (BMI) and waist height ratio (WHR) were examined for their potential association with depression and mental health after accounting for potential confounders.

About the study

The current study obtained data from the Cork and Kerry Diabetes and Heart Disease phase II clinical trial conducted between 1 May 2010 and 30 April 2011. Random sampling was performed from a primary care centre, with the final cohort comprising 1,800 participants.

BMI and WHR measurements were obtained after testing study participants for diabetes in the fasting state. Health and lifestyle characteristics were also assessed by questionnaire, along with a food frequency questionnaire to assess dietary factors presented as a Dietary Approaches to Stop Hypertension (DASH) diet score.

Smoking, alcohol consumption, demographic factors including gender, age and education, physical activity and chronic diseases, namely diabetes, cardiovascular disease and cancers, were considered as potential confounders.

What did the study show?

More severe depression and lower mental well-being were associated with being female, younger, and diabetic, but negatively associated with physical activity. Study participants with less education and those who did not drink heavily had higher well-being scores.

BMI reflects total body fat, while WHR reflects central fat deposition or visceral fat. In the current study, both measures of body fat were significantly associated with depression.

People with higher body fat were more likely to be depressed in both sexes, even after controlling for lifestyle and obesity-related specific diseases. This association was stronger in women compared to men. However, both were important.

Increased obesity is associated with mental health.”

How does obesity affect mental health?

The study’s findings confirm previous research suggesting an increased risk of new-onset depression among obese individuals. This association could be mediated by reduced self-esteem, self-image, self-satisfaction due to obesity, which can increase the risk of depression.

Social factors may also influence this association, as obese people are often ridiculed or discriminated against in social situations. Obesity can also contribute to chronic joint pain or cause fibromyalgia, which can worsen symptoms of depression.

Both obesity and depression interfere with the chemical balance of neural transmission circuits, thereby disrupting the endocrine axis to cause inflammation, increased oxidative stress, mitochondrial dysfunction that compromises the body’s energy metabolism, and ultimately neurodegeneration.

Disruption of the neural and endocrine signaling system that regulates the body’s energy production and consumption may also contribute to the association between obesity and depression, as hormones such as insulin and leptin are also involved in food consumption. Furthermore, obesity and depression may be associated with neural pathways linking these homeostatic responses to circuits that help regulate mood.

Childhood poverty and other indicators of disadvantage predict adult depression. This could be due to adverse environmental and lifestyle factors, family instability and increased stress in life.

What are the consequences;

It remains unclear whether obesity causes depression or vice versa from the findings of this cross-sectional study. Therefore, further research is needed to elucidate the mechanisms responsible for this association.

Targeted interventions to reduce depression should include better weight management measures at the population level, particularly in middle-aged to older populations.”