Individuals at risk for Alzheimer’s disease show differential patterns of ERP brain activation during odor identification

Abstract

BackgroundStudies suggest that older adults at risk of developing Alzheimer’s disease may show olfactory processing deficits before other signs of dementia appear.MethodsWe studied 60 healthy non-demented individuals, half of whom were positive for the genetic risk factor the Apolipoprotein E ɛ4 allele, in three different age groups. Event-related potentials to visual and olfactory identification tasks were recorded and analyzed for latency and amplitude differences, and plotted via topographical maps.ResultsVarying patterns of brain activation were observed over the post-stimulus epoch for ɛ4- versus ɛ4+ individuals on topographical maps. Individuals with the ɛ4 allele demonstrated different ERP peak latencies during identification of olfactory but not visual stimuli. High correct ApoE classification rates were obtained utilizing the olfactory ERP.ConclusionsOlfactory ERPs demonstrate functional decline in individuals at risk for Alzheimer’s disease at much earlier ages than previously observed, suggesting the potential for pre-clinical detection of AD at very early stages.

Increased N200 and P300 latencies in cognitively impaired elderly carrying ApoE ε‐4 allele

“…Most of the studies with normal cognition subjects support an increase in the latency of ERP in ApoE 4+ patients. Morgan and Murphy observed, after olfactory stimulus in 60 non‐demented individuals, that N100 latency was the major discriminator between ApoE 4+ and ApoE 4−. Corby et al studied 40 non‐elderly individuals, half ApoE 4+, who received visual and olfactory stimuli.…”

Smell identification function and Alzheimerʼs disease

“…Studies suggest that declines in odour identification occur before declines in other measures of dementia in persons at risk for Alzheimer's disease because of their APOE allele genetic status [62][63][64]. Individuals with APOE e4 demonstrated different event-related potential (ERP) peak latencies during identification of olfactory but not visual stimuli, suggesting the potential for preclinical detection of Alzheimer's disease at very early stages [65]. A study that utilized an olfactory-visual semantic congruency task to investigate cross-modal odour identification disturbances in persons at genetic risk for Alzheimer's disease showed significant differences in olfactory performance as assessed by olfactory ERPs between e4 carriers, who are genetically predisposed to enhanced Alzheimer's disease risk, and non-carriers [66].…”

Η Σχέση Της Γνωστικής Γήρανσης Με Την Οσφρητική Ικανότητα: Σύγκριση Νέων, Μεσηλίκων Και Ηλικιωμένων Ως Προς Την Ικανότητα Ταυτοποίησης Οσμών

“…Sohrabi et al, 2009. Μάλιστα, έχει διαπιστωθεί πως ο συνδυασμός οσφρητικής επεξεργασίας με τη γνωστική επεξεργασία κατά την ταυτοποίηση οσμών, μπορεί να είναι αρκετά ευαίσθητος, ώστε να διαφοροποιηθεί πολύ νωρίς σε εκείνους που έχουν υψηλή πιθανότητα ανάπτυξης ΝΑ, σε σύγκριση με εκείνους με χαμηλή πιθανότητα (Morgan & Murphy, 2012).…”