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P‐032: Differentiation between Alzheimer's disease patients and healthy controls is not possible with 2‐[ 18 F]F‐A‐85380 pet imaging of nicotinic receptors
Author(s) -
Ellis Julia R.,
Nathan Pradeep J.,
Villemagne Victor L.,
Mulligan Rachel S.,
Gong Sylvia S.,
Smith Clare L.,
Tochon-Danguy Henri J.,
Woodward Michael,
Savage Greg R.,
Rowe Christopher C.
Publication year - 2007
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2007.04.248
Subject(s) - nicotinic agonist , neuropsychology , psychomotor learning , cognition , medicine , cholinergic , psychology , alzheimer's disease , neurology , neuroscience , cardiology , audiology , endocrinology , receptor , disease
Background: The cholinergic system and neuronal nicotinic acetylcholine receptors (nAChRs) are critical for higher order cognitive processes. Postmortem studies suggest reductions in nAChRs (particularly the 4 2 subtype) with ageing and in Alzheimer’s disease (AD), predominantly in frontal and temporal cortices. The radiotracer 2-[F]F-A-85380 binds with high affinity at nAChRs and its uptake is consistent with the known distribution of the 4 2 nAChR subtype. Objectives: This study aimed 1) to quantify the nAChR distribution in early AD patients compared to age-matched, normal elderly controls (HC) and 2) to correlate nAChR distribution with cognitive performance in AD and HC. Methods: Fourteen HC (MMSE 29 1, aged 72 9 years) and fifteen drug naı̈ve, early AD patients (MMSE 23 2, aged 77 10 years) all non-smokers, underwent neuropsychological testing designed to assess verbal learning, working memory, attention and psychomotor function along with a static 20-min PET scan acquired 100 min after injection of approximately 200MBq of 2-[F]F-A-85380. Brain regional 2-[F]F-A-85380 binding was assessed through a simplified estimation of Distribution Volume (DV(simplified)), defined as the ratio of regional activity to metabolite corrected venous plasma at apparent steady state (100-120min post-injection). Measures of cognition and DV(simplified) were analysed using t-tests and the relationship between DV(simplified) and measures of cognition were examined using correlational analysis. Results: The AD group differed significantly from the HC group on all cognitive measures employed (p .05 p .001). Statistical analysis showed no significant difference in nAChRs DV(simplified) between AD and HC. Furthermore, no significant correlations were found between cognitive measures and DV(simplified) for either group. Conclusions: Contrary to post-mortem research this in vivo study found no evidence of nAChR loss in early AD despite significant cognitive impairment. Furthermore, no correlation between nAChR and cognitive performance was found for either group. These results are in line with recent studies suggesting the stability of cholinergic markers during the early stages of AD.