Bipolar people are seven times more likely to develop Parkinson's disease later in life

New research shows that bipolar disorder can increase the risk of Parkinson's later in life.

The underlying issues related to both brain disorders are not yet clear, but scientists suspect factors such as inflammation, genetics, and communication problems between brain cells.

Bipolar disorder affects approximately 5.7 million people in the United States and becomes a serious disability for the vast majority of them at some point in their lives – more than any other mood disorder.

Parkinson's disease remains incurable and complications are the 14th leading cause of death in the United States.

Researchers at the Taipei Veterans General Hospital in Taiwan hope that finding the link between these two devastating conditions could make them easier to treat or even prevent.

According to a new study from Taiwan, people with bipolar disorder are about seven times more likely to develop Parkinson's disease later in life.

The team tracked more than 56,000 people diagnosed with bipolar disorder between 2001 and 2009, as well as 224,360 people who had never been diagnosed with this disorder until 2011.

Several differences between the two have become clear.

About seven times more people with bipolar disorder have developed Parkinson's disease than people with no mood disorder.

To be exact, 0.7% of the bipolar group had Parkinson's disease, while only 0.1% of the non-bipolar group had it.

Not only were people with bipolar disorder more likely to develop Parkinson's disease, but the symptoms appeared earlier in life.

The average Parkinson's patient without bipolar disorder was diagnosed at age 73, and those with bipolar disorder were diagnosed nearly ten years earlier, at age 64.

The results of the study, published in the journal Neurology, suggest that people with more serious bipolar disorder may also be more prone to Parkinson's disease.

People who needed to be hospitalized because of a mood disorder were more likely to develop Parkinson's disease.

And the more they had to be hospitalized, the more likely they were to develop Parkinson's disease.

The three percent of bipolar people hospitalized more than twice a year were six times more likely, and those hospitalized once or twice were four times more likely to lose motor control than those without a mood disorder.

Few studies have examined the links between mood disorders in general and Parkinson's disease despite their common neurological nature.

However, many have noted links between depression and Parkinson's disease.

In fact, depression is even considered a harbinger of Parkinson's disease because the disease changes brain chemistry to cause tremors and depression.

Like depression and Parkinson's disease, scientists believe that bipolar people can also have roots in the inflammatory response.

Parkinson's disease is mainly marked in the brain by a shortage of dopamine.

Scientists have barely touched on the causes of bipolar disorder, but some have suggested that disturbed circadian rhythms and increases in dopamine may explain the manic phases of bipolar disorder.

And the hippocampus, a part of the brain that is key to memory and emotion management, seems to contract faster in people with bipolar illness.

Scientists have observed disturbances of signaling in the same part of the brain in patients with Parkinson's disease.

But, in the end, "further studies are needed to determine whether these diseases share underlying processes or brain changes," said Dr. Mu-Hong Chen, author of the study.

"This could include genetic alterations, inflammatory processes, or message transmission problems between brain cells. If we could identify the underlying cause of this relationship, it could potentially help us develop beneficial treatments for both cases. "