Doctors and researchers have studied depression for many years. Dozens of risk factors and behaviors that influence the condition have been discovered. Many of those factors and behaviors are modifiable. Now, researchers from Massachusetts General Hospital (MGH) have narrowed that field down to a key few modifiable factors.
There are many factors influencing depression. Some of those factors can not be modified. Genetics plays a role, for example. But what if several key, modifiable factors could be drawn out of the larger field? What if those factors could then be adjusted through behavior? It’s possible that treating depression may change, if the MGH researchers are right.
There are over 100 modifiable factors that may be useful targets for preventing adult depression. In the study by the Massachusetts General team, which was published in The American Journal of Psychiatry, social connection was found to be the strongest of these. They also believe that watching less TV and napping less during the day can have a positive impact on preventing depression.
“Depression is the leading cause of disability worldwide, but until now researchers have focused on only a handful of risk and protective factors, often in just one or two domains,” says Karmel Choi, PhD, investigator in the Department of Psychiatry and the Harvard T.H. Chan School of Public Health, and lead author of the paper. “Our study provides the most comprehensive picture to date of modifiable factors that could impact depression risk.”
The research used a two-stage approach. In the first, the team scanned a wide range of modifiable factors that might be associated with increased risk of depression using records of over 100,000 people the UK Biobank. The Biobank is a world-renowned cohort study of adults.
The factors scanned included environmental exposure, physical activity, sleep patterns, diet, media use and social interaction. The method used is called an exposure-wide association scan, or ExWAS. It’s similar to genome-wide association studies (GWAS,) which have been used to pinpoint genetic risk factors for disease.
In the second stage, they took the strongest modifiable candidates from the ExWAS and applied Mendelian randomization (MR) to them. This allowed them to further examine which factors might have a causal relationship to risk of depression. MR is a statistical method which regards genetic variation between people as a variety of natural experiment to find whether an association is likely to be actually causal, or just a correlation.
Using a two-stage approach like this let the MGH team whittle the field down to a smaller group of what were most likely causal targets for depression.
“Far and away the most prominent of these factors was frequency of confiding in others, but also visits with family and friends, all of which highlighted the important protective effect of social connection and social cohesion,” points out Jordan Smoller, MD, ScD associate chief for research in the MGH Department of Psychiatry, and senior author of the study. “These factors are more relevant now than ever at a time of social distancing and separation from friends and family.”
Even for those people whose depression risk was high because of early life trauma or genetic vulnerability, social connection showed protective effects.
Watching TV for extended periods was another factor for depression risk. The researchers think more research is needed to see if that risk is from media exposure itself or whether that time watching TV is simply a proxy for sedentary behavior. Daytime napping behaviors seemed to be a risk factor, as did regular use of multivitamins. More research is needed to figure out the connection for both of these.
The study provides a way to evaluate a broad range of modifiable factors. It also offers an approach to use these factors as a means of developing preventive interventions for depression.
“Depression takes an enormous toll on individuals, families, and society, yet we still know very little about how to prevent it,” says Smoller. “We’ve shown that it’s now possible to address these questions of broad public health significance through a large-scale, data-based approach that wasn’t available even a few years ago. We hope this work will motivate further efforts to develop actionable strategies for preventing depression.”
It may also be possible to apply this two-stage approach to develop interventions for other health issues.
Keep the faith and keep after it!
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Journal Reference – Karmel W. Choi, Murray B. Stein, Kristen M. Nishimi, Tian Ge, Jonathan R.I. Coleman, Chia-Yen Chen, Andrew Ratanatharathorn, Amanda B. Zheutlin, Erin C. Dunn, Gerome Breen, Karestan C. Koenen, Jordan W. Smoller. An Exposure-Wide and Mendelian Randomization Approach to Identifying Modifiable Factors for the Prevention of Depression. American Journal of Psychiatry, 2020; appi.ajp.2020.1 DOI: 10.1176/appi.ajp.2020.19111158