PARKINSON'S DISEASE - A neurological disease first described in 1817 by James Parkinson. The pathology is not completely understood, but there appears to be consistent changes in the melanin-containing nerve cells in the brainstem (substantia nigra, locus ceruleus), where there are varying degrees of nerve cell loss with reactive gliosis along with eosinophilic intracytoplasmic inclusions (Lewy bodies). Biochemical studies have shown below normal levels of dopamine in the caudate nucleus and putamen. Symptoms include shuffling gait, stooped posture, resting tremor, and an eventual slowing of mental processes.