Bipolar Disorder is a psychiatric medical condition characterized by chronic and recurrent episodes of depression and mania or hypomania. The symptoms of Bipolar Disorder generally can be seen at a very early age with the average being around 20 years. The root cause of bipolar disorder is still not yet known but researchers believe that certain genetic and environmental factors play a role in the development of this condition. Additionally, researchers have found out an important role of dopaminergic system in the development of bipolar disorder. This is because the most common dopaminergic drug levodopa has shown to cause episodes of mania and hypomania in people with bipolar disorder. These episodes however tend to improve with the administration of antipsychotics.[1,2,3]
Researchers have also found evidence that suggests that moving from a manic to a depressive state in people with bipolar occurs in sync. There is also evidence that the switch from a depressive to a manic state occurs concurrently with an increase in dopamine receptors. Parkinson disease on the other hand is a gradually progressive disease of the brain that cause degeneration of the brain cells resulting in the symptoms of tremor, rigidity, impaired and restricted mobility, and problems with speaking, swallowing, and balancing. According to the National Institute of Health the risk of getting Parkinson disease increases with age.[1,2,3]
People with Parkinson’s disease usually take a drug called levodopa to help slow the degeneration of the brain which has been known to cause an increase in the symptoms of bipolar disorder as mentioned above. Additionally, the treatment for bipolar disorder includes medications like lithium and antipsychotic medications which are closely associated with drug induced Parkinsonism which is quite similar to Parkinson disease in terms of the symptoms that it causes including bradykinesia, resting tremor, muscle rigidity, and postural instability.[1,2,3]
Since drug induced Parkinsonism is quite common in people with bipolar sometimes physicians misdiagnose Parkinson disease as drug induced Parkinsonism. Unlike bipolar disorder, Parkinson disease is far more common in the elderly population. There have been some studies which show that bipolar disease tend to be seen more in people with Parkinson disease when compared to the general population.[1,2,3] The article therefore highlights whether bipolar disorder can cause Parkinson disease.
Can Bipolar Disorder Increase The Risk Of Parkinson Disease?
A recent study has revealed that people with bipolar disorder are really at an increased risk for developing Parkinson disease. This risk is magnified with increasing severity of bipolar. To investigate the link further, researchers from the Taipei veterans General Hospital started going deep into this finding. The findings of their research have now been published in the journal named Neurology. The researchers analyzed the health records of about 56,000 people with a known diagnosis of bipolar disorder in Taiwan. The people that were selected were diagnosed between the years 2001 to 2009. The data of these individuals was then compared with the health records of about 225,000 people who had no diagnosis of either bipolar disorder or Parkinson disease.
The health status of both the groups was closely monitored through 2011. After a close analysis, the researchers found out that about 0.7% of people with bipolar disorder went on to develop Parkinson disease during the study and only 0.1% of the people in the control group had it. To substantiate their findings the researchers then adjusted their data by taking into account the past medical and medication history, age, gender, or history of any brain injuries which all could have a potential bearing on the development of Parkinson disease.
After making all the necessary adjustments, they came to the conclusion that the risk of a person developing Parkinson disease was approximately 7 times more in people with a known diagnosis of bipolar disorder than the general population. Another significant finding was that the average age of people who had bipolar disorder and later on developed Parkinson disease was much less at around 64 years in average when compared to people who did not have a history of bipolar disorder at around 73 years in average.
The researchers also found that the severity of the bipolar disorder also had a major role to play in the development of Parkinson disease. The people who had to repeatedly go to the hospital for treatment for bipolar disorder were at the highest risk for developing Parkinson disease than others. It was noted that people who went to the hospital at least twice a year for bipolar disorder were four times more at risk for Parkinson disease than people who had fewer hospitalizations for bipolar. This risk increased to about 6 times in people who were hospitalized more than twice per year for treatment of bipolar disorder.
However, there are certain loopholes or limitations of the study conducted by the researchers from the Taipei Veterans general Hospital. The first thing was that the researchers included only those people in the study who took medical help for treatment of bipolar disorder. Such people are quite few as many people avoid going to a physician for this condition.
The second limitation of the study was that the researchers did not take into account any family history of Parkinson disease and other environmental factors that may increase the risk of developing Parkinson at a later age. The researchers states that more such studies are required to study whether there is any mechanism that is common for both bipolar disorder and Parkinson disease that may explain the close association between the two conditions.
They believe that genetic makeup, inflammatory processes, or disruption in transmission of signals from the brain may have a role to play here. They believe that once the cause of this association between bipolar disease and Parkinson is found then it will go a long way in helping find treatments that would be effective for both these conditions.