Parkinson's Disease is a neurological disease of unknown cause that involves a reduction in functioning of nerve cells in a deep part of the brain called the basal ganglia. This part of the brain plays an important role in normal movement and other functions. It usually begins in the 60s and 70s but may have an early onset as was the case with the actor, Michael Fox.
Classic symptoms mainly involve problems with movements and include tremor, rigidity, slowing of movements, and postural problems. There are other physical abnormalities which are fairly common such as a decreased sense of smell. What may be less well appreciated are the various mental health manifestations of the disease.
A common example is depression. This happens to about half of all patients with this disorder. Some may be due to the challenge of the loss of normal functioning that results. However, there is evidence that many cases are due to biochemical changes in the brain. For example, research has shown a decrease in the amount of serotonin in the brain of patients with Parkinson's Disease. Serotonin is considered important for the maintenance of normal mood. Depression is more common in people with a past history of depression.
Patients with depression usually benefit from standard treatments. Also, they typically respond well to ECT if the depression is severe enough to require it. Interestingly, a number of the patients also have a temporary improvement in some of their motor symptoms when given ECT.
Cognitive impairment is also fairly common with this illness. Many patients have no decline in mental functioning, but some do experience slowing in their thinking and disabilities that range from mild memory problems to full blown dementia. It can be difficult to know if cognitive problems are due to the Parkinson's Disease or to co-occurring Alzheimer's Disease, which is common in the usual age range in which Parkinson's Disease is found.
Patients with depression and cognitive decline have 50% less cognitive decline if their depression is treated. It has been shown by PET scans that depressed patients with Parkinson's Disease have lower metabolic activity in portions of the brain. Perhaps, this plays some role in the cognitive difficulties that may occur.
Sometimes, patients with Parkinson's Disease are thought to be depressed when they aren't. This is because they may look and sound depressed. These patients often develop muscle changes in their face such that they are relatively expressionless ("mask face"), and their voices tend to get very soft and without normal variation in pitch and tone such that it is rather flat. The lack of facial expression and soft, monotonous speech quality may give a false sense that the patient is depressed. However, when asked they will deny feeling sad or down.
Unfortunately, about 10% of patients develop psychosis that may be manifested by hallucinations and/or delusions. Unlike psychotic patients with schizophrenia, these patients do not often have auditory hallucinations. Rather, theirs is more likely to be visual. Sometimes, these hallucinations may be due to the illness itself, but in other cases it is a side effect of medications used to treat Parkinsonism.
If the patient has delusions that are paranoid in nature, they may become combative or verbally abusive. Sleep disturbances are quite common and may worsen the psychosis. The psychotic manifestations are frequent reasons for admission to a nursing home when they become too difficult for families to manage.
Anxiety disorders are also common in Parkinson's Disease. These include generalized anxiety disorder (feeling anxious frequently for no clear reason) and panic attacks. Such symptoms can be very distressing and may require treatment.
The bottom line is that Parkinson's Disease is a complex illness with a myriad of possible manifestations including psychiatric ones. Patients and their family members should watch for these symptoms and let your doctor know if they occur so they can be treated early in the course of the illness.
