Parkinson’s disease

Common chronic disorder of the part of the nervous system responsible for muscular co-ordination (the so-called extrapyramidal system), causing disturbed posture and movement, usually starting in middle age. The cause is low dopamine (a brain protein) levels because of a decay of certain cells in the deeper parts of the brain, with no clear cause; it may be encephalitis or a series of small strokes. Lowered dopamine content causes domination by the cholinergic cerebral proteins and affects brain cells, causing stiffness, reduced mobility and tremor. The first feature to attract attention is reduced swinging of the arms when walking. Because automatic movements are affected, the patient notices that he has to think consciously before he can perform certain movements. Walking becomes slower and more difficult, with an increasingly bent posture; sudden turning or stopping is difficult. On the other hand the patient may be able to move very rapidly in situations involving stress. Hand movements also become slower and more difficult: handwriting may become smaller and indistinct. The face is mask-like, and speech monotonous and indistinct. The tremor is most marked in the hands, which look as though they are counting money or rolling pills. Head and feet may also tremble. The tremor is most pronounced when the patient is at rest, and declines when purposeful movements have to be carried out. It is worsened by emotion. In the later stages the mind can be affected, and dementia may occur, together with psychological disturbances such as depression, confusion and sometimes even psychosis.