January 7, 2011
Dear Mayo Clinic:
Does Parkinson's disease affect memory and thinking? My 70-year-old husband has this condition and is showing signs of cognitive impairment.
Unfortunately, Parkinson's disease is not simply a problem of tremor, walking and movement. With advancing age, and the longer a person has the disease, difficulties with memory and thinking may surface. Typically, these problems are subtle at first, but may become progressively worse in some people with Parkinson's disease.
Parkinson's disease is a disorder of the nervous system that develops gradually over time. The development of cognitive problems reflects the progressive nature of the disease process. Early in the course of the disease, most symptoms — such as tremor, muscle rigidity and difficulty with movement — are usually mild and can often be effectively managed with medications.
After many years of Parkinson's disease, though, symptoms may become less responsive to medication, and new problems can develop. New symptoms can include additional movement problems and cognitive difficulties, as well as bladder and bowel issues and, in some people, low blood pressure.
The underlying cause of the advancing Parkinson's disease process cannot be seen on brain imaging studies, such as magnetic resonance imaging (MRI). However, we know from postmortem studies that, as Parkinson's progresses, microscopic changes increasingly develop in broad regions throughout the brain, including areas responsible for cognition that govern functions like thinking and memory.
At this time, we have no drugs that slow the progression of Parkinson's disease. Many symptoms, however, can be effectively treated with medications as well as other forms of treatment, such as physical therapy and surgery. Medications are available that improve memory, including those used to treat Alzheimer's disease, but they usually provide only modest benefit.
People with Parkinson's disease, such as your husband, who have recently developed cognitive problems, should be evaluated by their physicians to make certain that some other factor is not responsible for these symptoms. Often, the evaluation includes a head scan to exclude a stroke, blood clot or tumor, which could affect thinking. In addition, blood tests are also appropriate because general medical problems, such as thyroid dysfunction, nutritional deficiencies and other medical conditions, might affect thinking and memory.
Physicians should also review patients' drug lists, as medications for other health problems may sometimes compromise mental clarity. Finally, adequate sleep is important to sound thinking, and occasionally treating sleep disorders, such as sleep apnea, can improve cognition.
If factors such as these are ruled out, then it's very likely that progression of Parkinson's disease is the cause of impaired memory and thinking. If this is the case for your husband, talk to his physician about possible treatment options, as well as techniques your husband and you can use to help cope with advancing Parkinson's disease.
— J. Eric Ahlskog, M.D., Ph.D., Neurology, Mayo Clinic, Rochester, Minn.