title: Fluctuations in plasma dopamine level impair memory in Parkinson's disease.
abstract: We found a causal relationship between variation in plasma dopamine level and memory impairment in Parkinson's disease. If the level of dopamine was changed between the time of original learning and a later time of attempted memory retrieval, memory performance was impaired when compared with a maintenance of similar dopamine levels on both occasions. The absolute level of dopamine did not influence memory performance. Side-effects of levodopa-carbidopa therapy include variation in dopamine level, parkinsonian symptoms, and possibly "state-dependent" impairment of memory.
mesh_terms: D002230:Carbidopa / Q000627:therapeutic use; D004298:Dopamine / Q000097:blood* / Q000502:physiology; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008568:Memory / Q000502:physiology*; D010300:Parkinson Disease / Q000097:blood / Q000188:drug therapy / Q000503:physiopathology*
chemical_list: D007980:Levodopa; D002230:Carbidopa; D004298:Dopamine