Not just the public, but many clinicians, believe that Parkinson’s disease is exclusively a neurological disorder—that is, that it only entails tremors, stiffness, and difficulty with balance.
Yet there are many psychiatric aspects to the illness as well, psychiatrists who specialize in Parkinson’s disease stressed during recent interviews with Psychiatric News.
Parkinson’s patients can experience a raft of psychiatric symptoms, Daniel Weintraub, M.D., an associate professor of psychiatry and neurology at the University of Pennsylvania and a psychiatrist with the Parkinson’s Disease Research, Education, and Clinical Center at the Philadelphia Veterans Affairs Medical Center, reported. These symptoms include anxiety, depression, personality changes, memory problems, sleep problems, impulse control difficulties, psychosis, and dementia.
And these symptoms can occur at different stages of the disease and have different causes, Parkinson’s researcher Laura Marsh, M.D., pointed out. She is a professor of psychiatry and neurology at Baylor College of Medicine and director of the Mental Health Care Line at the Michael E. DeBakey Veterans Affairs Medical Center.
Among individuals with Parkinson’s, anxiety disorders develop at a higher rate than in the general population, Marsh indicated, and can have their onset up to 20 years or so before tremors and other motor aspects of the disease are apparent. Also, several studies show a high rate of a family history of anxiety conditions in such individuals. Thus it looks as if there could be genetic links between anxiety and Parkinson’s in some individuals.
As for depressive symptoms, they can also occur before the motor symptoms of Parkinson’s surface, Marsh noted, but closer than anxiety symptoms to the time that the motor symptoms appear. “I have seen a number of patients who had never had a mood disorder earlier in their life, but who developed a depressive disorder around age 55, followed by the motor symptoms of Parkinson’s three years later,” she said. And here too, it looks as if the depression may be an early sign of the parkinsonian disease process, not a reaction to the motor symptoms of the disease.
Indeed, “patients with depression will often say, ‘Why wouldn’t I be depressed? I have Parkinson’s,’ when in fact disability due to Parkinson’s motor symptoms is not correlated with depressive symptoms,” William McDonald, M.D., a professor of psychiatry at Emory University and a Parkinson’s researcher, told Psychiatric News. “Clinically we have found that some of the most disabled Parkinson’s patients are not depressed, and some of the most depressed Parkinson’s patients have only minor motor disabilities.”
The reason that anxiety and depression may be precursors of the appearance of Parkinson’s motor symptoms, Marsh suggested, may be due to the discovery, a few years ago, that the parkinsonian disease process starts in the brainstem and then advances to the midbrain. The brainstem contains serotonin and adrenergic neurons that could contribute to anxiety and depression, whereas the midbrain contains dopaminergic neurons that contribute to the motor symptoms of Parkinson’s, she explained.
The pathological gambling or hypersexuality that some Parkinson’s patients experience appears to be due, however, largely to the dopaminergic medications that patients are prescribed for their motor symptoms—not to the disease process itself, Marsh noted.
And the same is true for the hallucinations or delusions that some Parkinson’s patients experience, Weintraub added. However, as Marsh noted, “the evidence suggests that they are due not just to dopaminergic medications, but also to the disease process.”
Since psychiatric problems can be a significant part of Parkinson’s disease, what can psychiatrists do to help Parkinson’s patients? “Until relatively recently I couldn’t have answered this question very definitively,” Matthew Menza, M.D., chair of psychiatry at the Robert Wood Johnson Medical School and a Parkinson’s expert, said during an interview. “But I think that over the past decade, there have been a number of reasonably good studies that have begun to address the question.”
Regarding anxiety, for example, “One of the more interesting things that has been demonstrated recently is that exercise, which is a well-validated treatment for anxiety disorders in general, also appears to benefit Parkinson’s patients who are anxious,” Menza said.
Several randomized, double-blind, placebo-controlled trials have shown that antidepressants can help Parkinson’s patients who are depressed, Menza also pointed out. One of these was conducted by McDonald and his colleagues and is in press with Neurology. The trial has demonstrated that “Parkinson’s depression is very treatable using standard antidepressants and [these medications] can be remarkably effective in improving quality of life and even motor symptoms, with few adverse effects,” McDonald said.
Cognitive-behavioral therapy (CBT) can also benefit depressed Parkinson’s patients, Roseanne Dobkin, Ph.D., along with Menza and other colleagues at the Robert Wood Johnson Medical School, reported in the October 2011 American Journal of Psychiatry. Eighty depressed Parkinson’s subjects participated in a randomized controlled trial in which CBT was compared with clinical monitoring. CBT was modified to meet unique needs of the Parkinson’s population and was provided for 10 weeks. Assessments were completed by blind raters at baseline, midway through treatment, at the end of treatment, and finally four weeks later. The CBT group experienced significantly less depression by the end of treatment than the control group did, and these gains were maintained four weeks later.
Most people with Parkinson’s have some sleep problems. “It looks as if many of the drugs that we psychiatrists use for sleep disorders probably have some [positive] effect in people with Parkinson’s disease,” Menza observed.
Regarding the memory problems that are common later in Parkinson’s disease, the drugs available to treat Alzheimer’s disease “can help a bit,” he said.
“So psychiatrists, I think, have available to them a variety of medications and nonmedication therapies that may be useful for people with Parkinson’s,” he noted.
And still more psychiatric tools to help Parkinson’s patients may be emerging in the near future, Marsh indicated. For example, when most antipsychotic medications are given to Parkinson’s patients for hallucinations or delusions, the antipsychotics may eliminate the symptoms, but they may also block the action of the dopaminergic drugs given to control motor symptoms. As a result, the patients’ motor symptoms can get worse. New antipsychotics in the development pipeline might be able to treat psychotic symptoms successfully without increasing the patients’ motor symptoms.
“One of the great things about taking care of individuals with Parkinson’s disease, of all the neurodegenerative disorders, is that it has very effective treatments,” Marsh declared. “So even though it is a chronic, progressive, neurodegenerative disease, and even though it has no cure, people can live with it and do well despite its challenges, especially if the psychiatric problems are treated.”
Not that many, Laura Marsh, M.D., a professor of psychiatry and neurology at Baylor College of Medicine and a Parkinson’s researcher, told Psychiatric News. “And when they do, it is often because the problems have gotten out of hand—say, someone is really depressed or suicidal.”
And do neurologists ever seek out psychiatrists to help them with Parkinson’s patients’ psychiatric problems? “It really depends,” said Daniel Weintraub, M.D., an associate professor of psychiatry and neurology at the University of Pennsylvania. “If you are in a place such as I am, which is a large academic medical center, I do work closely with neurologists…. At other places where there may not be the same access to psychiatrists, where Parkinson’s care may not even be provided by movement-disorders neurologists but by a general neurologist, then I think that the collaboration is less likely to exist.”
Thus “in Parkinson’s disease, the psychiatric complications remain underrecognized or undertreated,” Marsh asserted.
So how might psychiatrists reach out to help Parkinson’s patients?
One way is to become involved in interdisciplinary care teams and learn about the motor and other somatic and cognitive features of the disease, Marsh suggested. “It is a rewarding condition to treat psychiatrically because treatment works.”
Also, psychiatrists should stay alert for Parkinson’s in older adults who are depressed, George Grossberg, M.D., a professor of psychiatry and neurology at St. Louis University and a geriatric psychiatrist with an interest in Parkinson’s, advised during an interview. “Often we psychiatrists may be the first ones to suspect Parkinson’s in such patients,” he said.
Moreover, psychiatrists who consult to assisted-living facilities or nursing homes should be especially vigilant for Parkinson’s disease in patients, Grossberg said, since neurologists who specialize in Parkinson’s rarely provide such consultation.
“There is an energetic effort right now to find treatments that slow the progression of Parkinson’s,” Matthew Menza, M.D., chair of psychiatry at the Robert Wood Johnson Medical School and a Parkinson’s expert, said during an interview. The effort is focused on neuroprotective treatments such as nonsteroidal inflammatory drugs, since there is substantial evidence that inflammation is involved in the Parkinson’s disease process.
“Many of the disorders that we deal with in psychiatry start early in life—in childhood or adolescence—and some of them appear to get worse over the years,” he said. “So if we had a treatment that was neuroprotective, it might have application in psychiatric disorders. True, nothing is ready for prime time right now. But it is certainly something that people are thinking about.”
“Parkinson’s disease is in many ways the prototypical neuropsychiatric disorder in that it causes clear damage to the brain, but also has many psychiatric aspects to it,” Menza observed. “The hope of those of us who work in this interface between psychiatry and neurology is that if we understand more about Parkinson’s, it’s going to lead to a better understanding of many other diseases that we believe are based in the brain, such as attention-deficit/hyperactivity disorder, bipolar depression, and schizophrenia….[And] if we understood Parkinson’s better, we might have better insights into how to treat these other purely psychiatric disorders.