Parkinson's disease is a degenerative neurological disorder. It generally has a slow onset, usually in those over the age of 60, though it can be found in people in their 40s. While the disorder is thought to affect more than six million people worldwide, no specific diagnostic test for primary PD has been found.
Neurological Exam Plus Medical History
Parkinson's disease cannot be detected by a specific test; instead it is diagnosed through the taking of a thorough medical exam and the manifestation of four specific symptoms: a tremor in the hands, face or legs while at rest; slow movements, especially when trying to initiate a movement; balance and coordination problems, also called postural instability; rigidity in the trunk or limbs.
These four main symptoms may start on only one side of the body--for example, a tremor in one hand, or rigidity of one leg--but eventually migrate to the other side. These symptoms generally progress slowly, but that isn't always the case.
Because there is no definitive test for PD and because so many of the early symptoms may easily be attributed to the aging process, the disease is frequently misdiagnosed. To limit that possibility, it's a good idea to seek out an experienced neurologist if you suspect you or a loved one has Parkinson's.
Tests To Rule Out Other Conditions
In addition to a medical history and neurological exam, your doctor may order imaging tests, such as a CT or MRI exam. These are not done to diagnose PD--they most often appear normal in those who have the disease--but may be needed to rule out other conditions. The results of these tests may lead to a diagnosis of secondary Parkinson's disease or Parkinsonism, or a condition that mimics some of the primary symptoms of PD. Parkinsonism may result from the use of certain types of medications, encephalitis or atherosclerosis. In some instances, symptoms of Parkinsonism are reversible.
Biomarkers and Genetic Testing
Research is being conducted to find tests to help with early diagnosis of Parkinson's. One promising area is in discovering a biomarker--an abnormality in the cells that could be identified in people with the disease. The hope is that if such a biomarker could be found, a simple screening test could be given to those most at risk or those showing any of the early signs of Parkinson's.
While much research is focused on the genetics of PD, only a very small percentage of Parkinson's is known to be inherited and, therefore, subject to genetic testing. For inherited PD, genetic testing may identify mutations that determine a person's risk of getting PD. However, these tests are still in the research stages, and so are not yet available to the general public. When they do become more widely available, it may be a wise to give some thought to the many ethical, social and even legal questions that arise with any genetic testing.
