The Prevention of Parkinson Disease

Parkinsonism is a general term to describe symptoms caused by degeneration of part of the brain devoted to control of bodily movements. Under this overall heading we include not only Parkinson disease (PD) in its strict sense, but also analogous conditions, such as the tremor that affects many older people who do not have PD itself.

PD is caused by the loss of neurons in a circuit that controls movement and that normally produce dopamine, a neurotransmitter that propagates the nerve impulse across the synapse. It is not difficult to see that such a loss will disturb neurotransmission and thus the control of movements, giving rise to tremor, stiffness of the limbs, slowness of movements and even the loss of the ability to move, that are the best known characteristics of the disease. Initially PD is different from Alzheimer disease in that it attacks motor function rather than cognition, but ultimately many PD patients suffer from a psychological degradation.

Parkinsonism is due in about 80% of cases to PD itself. Its name is derived from that of James Parkinson (1755–1824), an English physician who first described it in 1817. His description concentrated on muscular rigidity and spasms associated with tremor. In 1860 French neurologist Jean-Martin Charcot (1825–1893) proposed to name the disease after Parkinson. It is estimated to affect between 6 and 16 million people in the world, and is likely to double by 2040. In most countries it affects between 1 to 3% of the population. Symptoms usually appear in people over 50, but in 5% of cases it is diagnosed before the age of 40. Men are affected slightly more frequently than women.