Parkinson’s Disease is a complex condition. Actually, it’s more accurate to say that Parkinson’s is a family of closely related conditions, each of which affect the brain in different ways.
Parkinson’s progresses differently in different patients. In fact, it’s problematic to say that there’s a “standard” progression of the disease. Particular Parkinson’s symptoms become more likely to appear at different stages, but any patient hoping to set his or her watch by the disease’s presentation is likely to be sorely disappointed.
These caveats aside, recent research suggests a link between depression and PD. A landmark study of more than 100,000 Parkinson’s patients found that patients who have been diagnosed with depression at some point in their lives are more likely to be diagnosed with Parkinson’s sometime down the road.
This isn’t necessarily a causative relationship. It’s not accurate to say that depression causes Parkinson’s disease or vice versa. However, the link between depression and Parkinson’s is certainly worth exploring. Here’s a brief rundown of the study’s findings and a look at what they mean for the average person.
Study Term and Parameters
The study, overseen by researchers from Sweden’s Umea University, followed about 140,000 people who were diagnosed with depression between 1987 and 2002. Study participants ranged widely in age, but all had turned 50 by 2005.
Each study participant was matched with a similar individual (in terms of age, gender, demographics, and health status) who was not diagnosed with depression during the study period. Over the course of 26 years, the study administrators compared rates of Parkinson’s diagnosis among the study group with those among the control group.
The headline finding was this: study group members were more than twice as likely to develop Parkinson’s Disease during the course of the study than members of the control group. Roughly 1 percent of the study group had been diagnosed with PD by the end of the study, compared to about 0.4 percent of the control group.
Other Notable Findings
Study participants with depression were significantly more likely to develop Parkinson’s Disease earlier in life. According to the study authors, people with depression were diagnosed with PD within a year of the study’s start and at more than three times the rate of people without depression, suggesting a link between depression and early-onset PD.
Additionally, there appeared to be a direct correlation between the severity of depression symptoms — as measured by hospitalization rates and other objective factors — and the likelihood of PD development. Study participants who had been hospitalized for depression at some point were more than three times as likely to develop PD as those who’d never been hospitalized.
Reality Check?
The apparent link between depression and Parkinson’s Disease is decidedly not cause for alarm. If you were diagnosed with depression in early life, and/or you still struggle with the disease today, you shouldn’t expect to develop other Parkinson’s symptoms as you age. Likewise, you might develop Parkinson’s without ever experiencing the symptoms of depression.
Parkinson’s and depression are both dependent on a host of different factors, many of which we’re still learning about, and some of which we likely aren’t even aware of at present. Right now, the best thing you can do is keep this news in perspective and carry on with your life.
John Gorecki MD 