Dementia, gliosis and expression of the small heat shock proteins hsp27 and alpha B-crystallin in Parkinson's disease

COGNITIVE impairment and dementia are common in the later stages of Parkins on's disease (PD). Neuropathological examination of demented PD (PDD) patie nts often reveals changes that are typical of Alzheimer's disease (AD). In AD, there is a massive reactive gliosis and increased expression of the sma ll heat shock proteins (hsp) hsp27 and alpha B-crystallin. Since these prot eins are characteristic for reactive astrocytes in AD, we investigated thei r expression in the brains of PDD patients. The results were compared with those obtained in the brains of non-demented PD patients. We found (1) no d etectable expression of hsp in PD without dementia, and low expression in P D with mild dementia; (2) reactive gliosis and increased expression of hsp in the cortex of PDD brains; (3) a strong association between hsp immunorea ctivity and the severity of the AD-specific changes, especially with the nu mber of tangles in the hippocampus; (4) a distinct immunoreaction of alpha B-crystallin in microglia in the substantia nigra and in the hippocampus in PDD. These results indicate that astrocytes react to the disease condition s in AD and in PDD in a similar way, namely by the increased expression of small heat shock proteins, and present additional evidence for the thesis t hat the pathology of the dementia in PD is related to that in AD. NeuroRepo rt 10:2273-2276 (C) 1999 Lippincott Williams gt Wilkins.