Parkinson's disease is a slowly progressive, neurodegenerative disorder affecting one in 1,000 of the general population; its incidence increases with age, but the cause remains unknown. The disease is characterized pathologically by a loss of neurons from the pigmented substantia nigra pars compacta, and a triad of physical symptoms of rigidity, tremor, and bradykinesia or akinesia . Thus the clinical condition of Parkinson's disease is a rather complex disorder with a variety of physical symptoms due to neuronal damage in a number of brain regions. Additional brain regions also affected in clinical Parkinson's disease include the ventral tegmental area, locus coeruleus, serotonergic dorsal raphe system, and the dorsal motor nucleus of the vagus ( I) . Furthermore, it has been suggested that damage to these various regions of the brain leads to a variety of motor and mental disorders (depression and dementia) that are specific to the damage in each of these neuronal systems (2) . Loss of norepinephrine may lead to depression; the incidence of depression varies between 20 to 90 percent in Parkinson's disease, and many of these patients show favorable responses to tricyclic antidepressants.
Gupta, MD, B.K.
"Synthetic Heroin-Induced Parkinsonism,"
Jefferson Journal of Psychiatry: Vol. 4
, Article 11.
Available at: http://jdc.jefferson.edu/jeffjpsychiatry/vol4/iss2/11