Depression a genetic cause for 20 diseases

New research shows that major depressive disorder is to blame for at least 20 distinct diseases; while alarming, this finding can help detect and manage high rates of physical illnesses in those diagnosed with depression.

A study from the Australian Centre for Precision Health, at the University of South Australia, found a causal relationship between depression and a range of respiratory, heart and digestive diseases including asthma, coronary heart disease, high cholesterol, oesophagitis, gastroenteritis, E. coli infections and urinary system disorders.

This can, the researchers said, provide vital information to help detect and manage high rates of physical illnesses in people diagnosed with depression.

UniSA researcher Anwar Mulugeta said that understanding the relationship between depression and other diseases can reduce the incidence of comorbidities – that is, “the presence of one or more additional conditions occurring with a primary condition – and improve the lives of millions of people worldwide”.

“Data shows that people living with serious mental diseases, like depression, have much higher rates of physical illness than those in the general population,” he said.

“But until now, these studies have been complicated by the possibility of other confounding factors, or even reverse causation where the physical condition is assumed to cause depression. This research puts the ‘chicken and egg’ conundrum to rest, showing that depression causes disease, rather than only the other way around.

“Importantly, this research signals that an individual diagnosed with depression should now also be screened for a defined set of possible comorbidities, enabling much better clinical management and significantly improved outcomes.”

The study assessed data from 337,536 UK Biobank participants to confirm the range of diseases affected by depression and was led by the director of the Australian Centre for Precision Health, Professor Elina Hyppönen, who said that appreciating the link between depression and distinct comorbidities has “important implications for individuals, practitioners and policymakers”.

“Today, nearly half of the population is estimated to experience a mental health condition in their lifetime,” she said.

“Understanding the connections between depression and other diseases is critical to ensure people with depression receive the support they require. The more we can look at the individual patient, the better their outcomes are likely to be.

“Our results suggest that it is important to look beyond the obvious, and that we need to screen and effectively manage depression-related comorbidities if we want to minimise the longer-term negative implications on health.”

It is also important to focus on diet and encourage healthy lifestyles in this context, Professor Hyppönen continued.

“It was concerning to see that depression was associated with multiple inflammatory and even haemorrhagic gastrointestinal complications, which may be due to side effects from medications used to treat depression, or even due to the greater occurrence of E. coli infections, both of which could be prevented,” she said.

“Through this study, we provide critical evidence to help navigate the complexities of depression and its comorbidities, with the ultimate goal of delivering customer-centric treatment strategies for people suffering from this debilitating disease.”

The research was published in Molecular Psychiatry.