Is there a link between depression and developing Parkinson’s disease?

Up to 60 percent of people who are living with Parkinson’s disease experience mild to moderate symptoms of depression and anxiety. But a new study has found data that may suggest another connection between the diseases that could link being diagnosed with depression with an increased risk of developing Parkinson’s disease.

Understanding the research

The study was conducted by researchers in Sweden who were exploring the relationship between depression and Parkinson’s. Other researchers had found that people who were diagnosed with Parkinson’s disease reported higher than average rates of depression before their diagnosis, most notably in the years just prior to the development of motor symptoms such as balance problems, tremors, uncontrollable movements and difficulty walking.

In the current study, the team reviewed a database that included all citizens of Sweden who were 50 or older in 2005, a total of 3 million people. From the larger group, they identified 140, 688 people who had been diagnosed with depression during a span of 25 years. They matched each study subject with depression with three people from the database who did not have depression and who were the same age and sex to act as a control group.

The researchers examined the health records of all participants, checking for Parkinson’s disease diagnoses, following some of the study participants for 26 years. Approximately 1.1 percent of those who were diagnosed with depression were ultimately also diagnosed with Parkinson’s. In contrast, only .04 percent of people who did not have depression were eventually diagnosed with Parkinson’s.

Participants were diagnosed with Parkinson’s an average of 4.5 years after their depression diagnosis. Researchers also found that people who were hospitalized for depression were 3.5 times more likely to be diagnosed with Parkinson’s disease and the risk was even higher for those who were hospitalized more than one time. For those hospitalized five times or more, the risk was 40 percent greater than for those hospitalized only once.

The research team noted that the findings of the study can be interpreted two ways. Either depression may be an early symptom of Parkinson’s disease or depression is a factor that increases the risk of developing Parkinson’s. They hypothesize that depression may damage certain areas of the brain in a way that makes it more susceptible to Parkinson’s or, because Parkinson’s disease damages areas of the brain that control moods, that the early stages of the disease may trigger depression.

Significantly, they also noted that most people who are diagnosed with depression are never diagnosed with Parkinson’s, so more study is needed to understand the link between these two diseases.

Proactive steps you can take

Because the causes of Parkinson’s disease have not yet been uncovered, there is no definitive approach to preventing the disease. Several studies have linked regular aerobic exercise in your 30s and 40s with a lower risk. Other studies have found that following a Mediterranean diet and eating less red meat and dairy may offer some protection.

If you have a history of depression, make sure your primary care physician knows about it. That information can help him or her develop a strategy to monitor you for any early symptoms of Parkinson’s disease.

If you’ve recently been diagnosed with Parkinson’s disease, it’s wise to get a second opinion. Other diseases, including Alzheimer’s disease, share similar symptoms, but call for very different types of treatment, so it’s important to get a clear diagnosis.