Abstract
The pathological basis for dementia in Parkinson's disease (PD) is related to the simultaneous presence of Alzheimer disease (AD)-like changes, thus suggesting a close link between PD and AD.
Recently AD is though to be associated with degeneration of cholinergic nervous system, as evidenced by selective loss of neurons in the Nucleus basalis of Meynert (NbM), the principal source of cholinergic projection to the neocortex. In order to examine the neuropathological changes of the cholinergic nervous system in PD with dementia, “diffuse Lewy body disease” and SDAT, comparative cell counts in the NbM were carried out.
The examined cases were as follows; PD without dementia (five cases, mean age 76.4 yeras), PD with dementia (five cases, 78.4 years), “diffuse Lewy body disease (DLBD)” (five cases, 84.2 years), SDAT (five cases, 76.4 years), PSP (three cases, 75.0 years), SND (two cases, 63.5 years) and five cases of normal control (mean age of 80.3 years). Compared to the control cases, the cell density (measuring 200um by 150um) and the total number of neurons (neurons mainly located between the optic tract and the anterior commissure) of the NbM in patients with SDAT, DLBD, and PD with dementia showed a statistical sifnificant reduction; the cell density was reduced by 26.6% (SDAT), 28.6% (DLBD) and 64.8% (PD with dementia), respectively. The total number of cells was also reduced by 26.05 (DSAT), 26.1% (DLBD) and 60.9% (PD with dementia), respectively. There was no statistical difference in cellular population of the NbM between PD without dementia, PSP, SND nd normal controls.
Our results show that the demented patients with PD as well as SDAT or “DLBD” have a loss of neurons in the NbM, suggesting a disturbance of cholinergic nervous system, which might be in part, related to dementia in these cases.
On the other hand, according to the distributing pattern of Lewy bodies, the demented patients with PD and “DLBD” may have a degeneration of meso-limbic-cortical dopaminergic pathways. Therefore, it may be postulated that PD with dementia and “DLBD” may have a system degeneration of both dopaminergic and cholinergic nervous systems in the brain. We also discussed the nosological situation of “DLBD”, regarding it as one distinct disease entity.
