Causes of neuronal death in Parkinson's disease.

The etiology of PD is complex and may depend on multiple factors, both hereditary and environmental. A proportion of PD disease patients show a deficiency in mitochondrial respiratory chain function, in particular a defect of complex I, within neurons of the substantia nigra. Both mitochondrial mutations and toxic agents (endogenous and exogenous) have been demonstrated to cause a deficiency in complex I function. This is achieved by increasing the degree of, or susceptibility to, oxidative stress, which may contribute to apoptopic cell death. Future research directed toward developing neuroprotective strategies may reduce oxidative stress and stabilize or improve mitochondrial function.