Nonmotor Manifestations of Parkinson’s Disease

The idea that Parkinson’s disease involves more than its classic motor symptoms (tremor, slowness, shuffling, etc.) is not new. Even James Parkinson recognized this in his seminal publication describing this disease in 1817. However, it is only in the last 25 years or so that neurologists have taken a serious, in-depth look at the nonmotor manifestations of Parkinson’s disease. What they have found has evolved into a rich field of study that has both permitted a greater understanding, and revealed greater levels of complexity, of Parkinson’s disease than previously known.

So many nonmotor manifestations have been attached to Parkinson’s disease now that for the sake of discussion they must be organized into subgroups. Classification schemes vary, but usually follow major functions of the nervous system. A typical breakdown would include cognitive and psychiatric complications, autonomic nervous system disturbances, sensory abnormalities and sleep disorders. Each of these categories comprises a number of distinct problems, although they are often interrelated.

The term “cognitive” is meant to capture those higher functions of the nervous system usually recognized by the terms “thinking”, “processing”, decision-making, memory, communication, and so on. “Dementia” refers to a state of loss of more than one of these capacities. People with Parkinson’s disease have a higher risk of dementia. It is an ominous development, not only due to the symptoms it produces, but also because it imposes limitations on our ability to treat the other manifestations of Parkinson’s disease.

There are a number of psychiatric complications of Parkinson’s disease. In this context, “psychiatric” is a jargon term that does not refer so much to a part of the nervous system as to a group of disorders that physicians recognize as usually falling under the purview of psychiatrists. Foremost among these is depression, which will affect about 50% of people with Parkinson’s disease at some point. Many people assume that it results from a reaction to disability, but depression often occurs before people even know they have Parkinson’s disease, and is a nonmotor manifestation that may precede the motor symptoms by many years. Another common psychiatric complication is hallucinations, which usually represent an interaction between the brain disease and the medications people take. Psychiatric manifestations of Parkinson’s disease are frequently considered alongside of cognitive complications because they often coexist. They are both major sources of care partner/caregiver stress.

The autonomic nervous system is that part of the nervous system that functions “autonomously”, meaning on its own. It includes a variety of bodily functions that are usually governed by a system of reflexes that are not under our conscious control. Major responsibilities of the autonomic nervous system include regulation of blood pressure and heart rate, bladder and sexual function, digestive and bowel function, and control of perspiration and body temperature. All of these are potentially disrupted by Parkinson’s disease. The most common symptom of autonomic impairment is constipation. Two that seem to cause the most disability are an inability to maintain blood pressure when upright, resulting in lightheadedness and fainting, and loss of bladder control.

Sensory disturbances are an underappreciated aspect of Parkinson’s disease. They include the loss of the sense of smell, also a feature that can precede motor manifestations by years. Another common sensory complication is the restless legs syndrome. This disorder occurs in about 3-4 % of the general population, but in about 20% of those who have Parkinson’s disease.

Sleep disorders in Parkinson’s disease have been the object of considerable study in recent years. They include insomnia, excess daytime sleepiness, and a peculiar tendency to act out one’s dreams known as REM-sleep behavior disorder. This last complication has become a major tool of researchers, because of its striking ability to predict the development of Parkinson’s disease and related disorders many years beforehand.

Nonmotor manifestations are responsible for much of the disability and loss of quality of life of Parkinson’s disease. For many, nonmotor symptoms represent their greatest challenge in dealing with this disease. It is impossible in this introductory article to even mention all nonmotor complications of Parkinson’s disease, much less give adequate attention to any of them. Each has important implications for the course of the disease and how it needs to be addressed. In future articles, I hope to revisit each of these topics in the degree of detail that it deserves.

David E. Riley, M.D.

Based on a talk given at InMotion on June 4, 2015

Posted in Dr. David Riley, For Care Partners, For Clients, For Referral Partners, What I tell my Patients.
Dr. David Riley

Dr. David Riley

Dr. David Riley has been active in the field of movement disorders for over 30 years. He retired as director of the Movement Disorders Center at University Hospitals in Cleveland in 2013 and as Professor in the Department of Neurology of Case Western Reserve University School of Medicine in 2014. A native of Montreal, Quebec, Riley received his M.D. from McGill University School of Medicine. Following a fellowship in Movement Disorders at Toronto Western Hospital under Dr. Tony Lang, Dr. Riley returned to Cleveland in 1988 to establish Cleveland's first movement disorders clinic at Mt. Sinai Medical Center.