Cholinergic deficit in Alzheimer's disease: a study based on CSF and autopsy data

Area of Science:

• Neuroscience
• Biochemistry
• Neurology

Background:

• Cholinergic neurotransmission plays a crucial role in cognitive functions.
• Alzheimer's disease (AD/SDAT) is characterized by progressive neurodegeneration.
• Identifying reliable biomarkers for AD/SDAT diagnosis is essential.

Purpose of the Study:

• To evaluate cholinesterase (ChE) activity in cerebrospinal fluid (CSF) as a potential biomarker for Alzheimer's disease (AD/SDAT).
• To investigate the distribution and extent of cholinergic deficits in various brain regions of AD/SDAT patients.

Main Methods:

• CSF samples from 93 AD/SDAT patients and 29 controls were analyzed for ChE activity.
• Autopsy brain tissue from 20 AD/SDAT patients and 14 controls was analyzed for cholineacetyltransferase (ChAT) and ChE activity in ten brain areas.

Main Results:

• CSF ChE activity was significantly reduced in AD/SDAT patients, correlating with dementia severity, but the reduction was moderate and not significant in early stages.
• Cholineacetyltransferase (ChAT) activity was profoundly decreased (50-85%) in cortical and hippocampal areas of AD/SDAT brains.
• Other brain areas, such as the striatum, showed less significant reductions in ChAT and ChE activity, indicating localized cholinergic neuron involvement.

Conclusions:

• CSF ChE activity is not a sufficiently sensitive or specific marker for diagnosing AD/SDAT.
• Cholinergic deficits in AD/SDAT are primarily localized to projections from the nucleus basalis to the cortex and hippocampus.
• The study highlights the importance of brain tissue analysis for understanding the specific neurochemical pathology of Alzheimer's disease.