Grant: Doctoral Research Award: Canada Graduate Scholarships

Subjective Cognitive Decline (SCD) is a preclinical stage of Alzheimer Disease (AD) characterized by the presence of non-objectified cognitive complaints during the assessment of cognitive functioning by conventional tests. However, although SCD constitutes a sensitive marker for the development of AD, it is not very specific. To improve its specificity, one solution would be to combine it with other early markers of AD. Olfaction is a potential candidate. Indeed, altered olfactory abilities have been demonstrated in AD and more recently, this alteration has also been observed in people with SCD. However, no study has looked at the neurophysiological changes responsible for these olfactory changes in individuals with SCD. A few recent studies report abnormal brain activity patterns (longer latencies and smaller amplitudes) in patients with AD using electrophysiological measurements of the olfactory system (olfactory event-related potentials - OERPs). Thus, this project aims to evaluate the functioning of the olfactory system in a preclinical stage of AD using behavioral and electrophysiological measures. Our hypotheses are that (1) individuals with SCD have lower behavioral olfactory scores than controls; (2) individuals with SCD have longer OERPs latencies and smaller OERPs amplitudes than controls; (3) Latencies and amplitudes observed in the OERPs of individuals with SCD will predict their scores on olfactory tests. To test these hypotheses, 80 individuals with SCD and 80 control participants matched by gender and age will be recruited and invited to the laboratory for evaluation. Olfaction will be assessed on behavioral and electrophysiological levels. Other cognitive tests will complement the evaluation. This research will allow the development of new tools for early detection of AD that will help to initiate rapid action before the onset of cognitive symptoms.