People like boxing legend Muhammad Ali and actor Michael J. Fox have helped to deepen the understanding of Parkinson’s disease as a movement disorder. Ali shows the most conspicuous symptoms of Parkinson’s; a slow, shuffling gait, rigid movements, hand tremors, and an expressionless face. Fox, on the other hand, shows many common side effects of treatment for the disease; dyskinesias—which are involuntary movements that produce rocking—unintended facial expressions, and random arm motion.
The motor symptoms of Parkinson’s—those related to movement—develop when a portion of the brain known as the substantia nigra stops producing enough of the neurotransmitter dopamine, which makes normal movement possible. But Parkinson’s also causes an array of non-motor problems. These symptoms may elude detection by doctors and even by patients themselves. Many of these symptoms seem to affect the mind more than the body; in reality, they illustrate the intimate connection between the mind and the body. For example, depression, anxiety, irritability, and social withdrawal are all recognized now as non-motor symptoms of Parkinson’s. Experts believe they are caused not by the person’s reactions to having Parkinson’s but by the disease itself and how it changes the physical brain. Because so many non-motor symptoms of Parkinson’s can be attributed to other causes, such as aging, stroke, or other neurologic disorders, it’s important for patients and caregivers to inform their neurologist about any changes in mood, attitude, and behavior, says Christopher G. Goetz, M.D., professor of neurological sciences and pharmacology and director of the Parkinson and Movement Disorders program at Rush University Medical Center in Chicago, IL, and Fellow of the American Academy of Neurology (AAN).“Patients and caregivers feel the burden of these non-motor symptoms,” Dr. Goetz says. “In my experience, they are relieved to find that the lack of energy, loss of endurance, and cognitive problems are part of Parkinson’s itself. It means that these symptoms are not the patient’s fault, nor are they part of another, separate disease the person has to contend with.”
OTHER NON-MOTOR SYMPTOMS OF PARKINSON’S
Many of the other non-motor symptoms of Parkinson’s may be overlooked as well. For example, the loss of the ability to smell is often an early symptom of Parkinson’s. In addition, people with PD frequently develop sleep problems, such as rapid eye movement (REM) sleep disorder, in which the normal paralysis that takes place during deep sleep fails. This causes sleepers to thrash about as they act out their dreams. Memory problems may develop in some people with Parkinson’s, along with difficulties in concentrating, problem solving, multitasking, and planning. These changes may be dismissed as the inevitabilities of aging or a reaction to the stress of having a chronic illness. Such problems, even when subtle, can have serious consequences. “I’ve had patients who are doctors and lawyers who can’t continue to work because of their cognitive impairment,” Dr. Kluger says. Problems with the autonomic nervous system, which is responsible for involuntary muscle function, may also accompany Parkinson’s and produce symptoms such as constipation, urinary incontinence, sweating, erectile dysfunction, and low blood pressure (hypotension)—symptoms often blamed on aging. Many patients also experience trouble swallowing. Even the treatments for Parkinson’s can cause non-motor symptoms. Treatments that restore dopamine function in Parkinson’s patients have been known to produce behaviors easily mistaken as character flaws, such as compulsive gambling and eating, excessive shopping and spending, sexual promiscuity, and Othello syndrome—the conviction, despite lack of evidence, that one’s partner is having sex with other people.