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Pathologic and nicotinic receptor binding differences between mild cognitive impairment, Alzheimer disease, and
Marwan N Sabbagh1, Flora Shah, Richard T Reid
1Cleo Roberts Center for Clinical Research, Sun Health Research Institute, Sun City, AZ 85351, USA. Marwan.sabbagh@sunhealth.org
Archives of Neurology
|December 19, 2006
Summary
Mild cognitive impairment (MCI) often precedes Alzheimer disease (AD). Nicotinic receptor binding remains stable in MCI but declines significantly in AD, suggesting a critical transition point.
Area of Science:
- Neurology
- Neuroscience
- Pathology
Background:
- Mild cognitive impairment (MCI) is a recognized precursor to Alzheimer disease (AD).
- Neuropathologic studies of MCI are limited by sample size.
- Neocortical nicotinic receptor binding changes in AD but remain unstudied in MCI.
Purpose of the Study:
- To compare nicotinic receptor binding and neuropathologic features in non-demented (ND) individuals, MCI patients, and AD patients.
- To investigate the transitional nature of MCI between normal aging and AD.
Main Methods:
- Clinicopathologic analysis of autopsy-confirmed cases.
- Inclusion of 21 ND, 8 MCI, and 70 AD subjects.
- Assessment of nicotinic acetylcholine receptor binding, tangle density, plaque density, and Braak stage.
Main Results:
- MCI subjects exhibited intermediate cognitive and pathological profiles between ND and AD groups.
- Nicotinic acetylcholine receptor binding was similar in ND and MCI groups but significantly reduced in AD.
- Some MCI cases lacked neuritic plaques, challenging their classification as early AD.
Conclusions:
- MCI represents a clinical and neuropathological transition to AD in most cases.
- The absence of neuritic plaques in some MCI cases suggests heterogeneity.
- Nicotinic receptor binding loss appears to occur during the progression from MCI to AD.
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