Relationship between Parkinson's and Alzheimer's diseases. Involvement of extrapyramidal, dopamnergic, cholinergic and somatostatin mechanisms in relation to dementia

Dementia with Lewy bodies

The advent of new immunostains have improved the ability to detect limbic and cortical Lewy bodies, and it is evident that dementia with Lewy bodies (DLB) is the second most common neurodegenerative dementia, after Alzheimer's disease (AD). Distinguishing DLB from AD has important implications for treatment, in terms of substances that may worsen symptoms and those that may improve them. Neurocognitive patterns, psychiatric features, extrapyramidal signs, and sleep disturbance are helpful in differentiating DLB from AD early in the disease course. Differences in the severity of cholinergic depletion and type/distribution of neuropathology contribute to these clinical differences.

Neuropeptides in Alzheimer's disease: a review and morphological results

The anatomic distribution of classical neurotransmitters, i.e. NA, DA, 5HT, ACH and GABA in the post-mortem autopsied brain of Alzheimer's disease (AD) has been reviewed. In addition, the results and reviews reported in this paper give evidence for the change of a large number of neuropeptides in AD on the basis of immunohistochemical criteria. Among numerous peptidergic systems, abnormalities in SP, SS, NT and VIP have been observed. Therefore, no changes in the concentrations of CCK and TRH were reported. In this study, using immunohistochemical methods for SS changes in post-mortem brain material of three cases of AD and two controls, the following changes were observed: An important reduction of the SS-positive cell bodies and fibres in the cortex, the hippocampus, parahippocampic cortex, and neocortex, particularly in the parietal and frontal areas, as well as a reduction of SS cell bodies and fibres in the sub-cortical white matter. An amorphous SS-positive material in or close to the corona of a number of senile plaques. An important decrease of SS fibres and cell bodies in the lateral septi nuclei. An increase of the number and immunoreactive intensity of SS-positive fibres in the substantia innominata. In animal studies, an interaction between SS- and ACH turnover in the substantia innominata is reported. The GABA decrease as well as the SS deficit in the cortex area and sub-cortical white matter may lead to the interaction between SS and other neurotransmitters in AD.