Parkinson's disease is a motor disorder characterized by the onset of a "pill rolling" rhythmic tremor, muscle rigidity, difficulty and slowness in movement, and stooped posture. As the disease progresses, the face of the patient becomes expressionless, the rate of swallowing is reduced, leading to drooling, and depression and dementia increase.
Although initially beneficial in causing a significant remission of symptoms, L-dopa frequently is effective for only 5 to 10 years, and serious side effects accompany treatment. Cotreatment with an inhibitor of the enzyme that breaks down L-dopa and thus allows the substance to remain in the brain longer has yielded an effective therapy, which allows many patients to live reasonably normal lives. Treatment of the disease with fetal tissue transplants, while raising ethical and legal issues, also has shown promise in alleviating symptoms. Nevertheless, although treatment may slow the progress of the disease, it does not alter its course. This suggests that factors other than variation in neurotransmitter levels are responsible for the disease.
Parkinson's disease affects about 1 of 250 people older than 40 and about 1 of 100 people older than 65. It commonly begins between the ages of 50 and 79. It is twice as common among whites as among blacks.
Parkinson's disease is a slowly progressive degenerative disorder of the nervous system characterized by tremor when muscles are at rest (resting tremor), slowness of voluntary movements, and increased muscle tone (rigidity).
PD is a chronic, progressive neurological disease that affects about 500,000 people in the United States. It results from the loss of brain cells that produce the neurotransmitter dopamine and causes tremor, stiffness of the limbs and trunk, impaired balance and coordination, and slowing of movements. Patients also sometimes develop other symptoms, including difficulty swallowing, disturbed sleep, and emotional problems. PD usually affects people over the age of 50, but it can affect younger people as well. While levodopa and other drugs can ease the symptoms of PD, none of the current treatments has been shown to slow the course of the disease.
Parkinsonism is a disorder with many or all of the symptoms of Parkinson's disease. Various conditions can cause parkinsonism. It may be a complication of viral encephalitis, a rare disorder that follows a flu-like infection. Parkinsonism may also result when other degenerative diseases, drugs, or toxins interfere with or block the action of dopamine and other neurotransmitters. For example, antipsychotic drugs, used to treat paranoia and schizophrenia, block dopamine's action. Use of the substance MPTP (which was produced accidentally when illicit drugs users tried to synthesize the opioid meperidine) can cause sudden, severe, and irreversible parkinsonism in young people. Other causes include structural brain disorders (such as brain tumors and strokes) and head injury, particularly the repeated injury that occurs in boxing.
Animal studies have shown that coenzyme Q10 can protect the area of the brain that is damaged in PD. Dr. Shults and colleagues also conducted a pilot study with PD patients which showed that consumption of up to 800 mg/day of coenzyme Q10 was well-tolerated and significantly increased the level of coenzyme Q10 in the blood.
The results of this study suggest that doses of coenzyme Q10 as high as 1,200 mg/day are safe and may be more effective than lower doses, says Dr. Shults. The findings are consistent with those of a recently published study of patients with early Huntington's disease -- another degenerative neurological disorder -- that showed slightly less functional decline in groups that received 600 mg/day of coenzyme Q10.