Prevalence and Stages
Parkinson's disease is a progressive neurological disease caused by the loss of neurons in a region of the brain that produces dopamine---a neurotransmitter necessary for proper functioning of most of the body, according to the Johns Hopkins School of Medicine. More than 1 million Americans have PD, which causes gradual deterioration in movement including gait, balance and coordination. In later stages, cognitive and affective functions are also impaired.
Symptoms of the disease develop when 80 percent of the dopamine in the brain is destroyed. Symptoms of PD usually appear in those 60 and older, although signs and symptoms present in people 40 or younger in 5 to 10 percent of PD patients. The cause of PD has not been established.
An early sign of Parkinson's is a noticeable reduction in the swing of one arm when walking. Gradually, both arms are affected and the patient develops a shuffling gait. Resting tremor of the hands, arms and legs is a common sign.
"Staging" of PD to determine how far the disease has progressed is based on functional limitations rather than symptoms, according to the Parkinson's Disease Foundation. Minor dysfunction on only one side of the body without limitations in daily activities defines stage one, for instance. The final stage refers to bed- or wheelchair-bound patients with significant limitations who require assistance with activities of daily living.
Progression is divided into five stages that range from early signs and symptoms that are mild, not disabling and often overlooked to the fifth, or end, stage in which the patient is unable to stand or walk and is completely dependent on others for care. In the second stage, symptoms such as rigidity of limbs, slowed body movement and postural changes present bilaterally. In stage three, early difficulties with equilibrium when standing or walking are evident.
In stage four, symptoms include marked changes in posture, problems with speech and sleeping, impairment of the autonomic nervous system and frequent falls. Psychiatric problems including depression and cognitive impairment develop. The fifth, or end, stage is characterized by complete loss of mobility and the need for constant nursing care.
The fifth, or end, stage of Parkinson's disease is a broad worsening of existing symptoms. Bowel and bladder incontinence are commonplace, as is loss of the ability to turn over in bed. Depression grows deeper as patients typically lose the ability to speak easily, accompanied by the inability to find the correct word. Speech becomes quieter and more difficult for the patient. Intellectual deterioration is evident.
Vulnerability to infections such a pneumonia increases, and the subsequent choking can cause death, although PD itself is not fatal. In end-stage Parkinson's, patients experience a loss of appetite and lose weight, have severe agitation, and difficulty breathing and swallowing. Because PD progressively destroys balance and coordination, falls become more frequent, with many trips to the hospital for injuries.
Anxiety disorders are common as PD progresses toward its end stage. Increased anxiety results from the underlying neurodegenerative process, and patients may develop phobias about such things as going out in public or being in confined spaces. Hallucinations, delusions and personality changes also can occur.
Parkinson's responds well in its earlier stages to treatment with dopamine-stimulating drugs such as roprinirole and pramipexole combined with levodopa, a dopamine precursor that converts to dopamine in the brain. However, after five years of treatment with these drugs, their effectiveness decreases.
Psychiatric symptoms, including profound depression, are often managed with the administration of antidepressant medications. Because some psychoses may be drug-induced, reduction in doses of these medications is often necessary.
Surgical deep-brain stimulation has been found to improve neuromuscular functions and reduce the need for other medications. Physical therapy can help with movement disorders, and speech therapy can effectively treat speech and voice disorders. Nutritional counseling can help relieve the chronic constipation associated with PD.