Jean-François Gagnon, Université de Montréal

REM sleep behaviour disorder and REM sleep without atonia in probable Alzheimer disease

Alzheimer's disease and Lewy body Dementia are two of the most frequent neurodegenerative disorders found in the elderly. Given the differences in the way these disorders evolve and in their therapeutic management, arriving at precise diagnoses for these two diseases remains a challenge for clinical practice and research in the field of aging. Dr. Jean-François Gagnon has undertaken a study of REM sleep behaviour disorder, a disorder characterized by the appearance of undesired motor behaviour during sleep. Although REM sleep behaviour disorder is frequent in cases of Lewy body Dementia, its frequency in Alzheimer's disease had not been confirmed previously in a sleep study conducted in a laboratory.

Research results now indicate that REM sleep behaviour disorder is rare in Alzheimer's disease patients. Thus, the presence of this sleep disorder in individuals with severe cognitive difficulties suggests a diagnosis of Lewy body Dementia rather than Alzheimer's disease. Sleep assessment done in a laboratory is an appropriate method in cases whenever a diagnostic dilemma exists for a patient with dementia or when a clinical interview suggests the presence of a REM sleep behaviour disorder.

During his doctoral and postdoctoral studies, Dr. Gagnon maintained an interest in sleep-related problems occurring within the context of neurodegenerative disorders, most especially in Parkinson's disease. In conducting this research on Alzheimer's disease, Dr. Gagnon has sought to widen his horizons and skills with a view to future research efforts. As part of his new duties as an independent researcher at the Centre d'étude du sommeil et des rythmes biologiques (centre for studies on sleep and biological rhythms) at Hôpital du Sacré-Coeur de Montréal, Dr. Gagnon will be directing work funded by FRSC (Fonds de la Recherche en Santé du Québec) on the impact sleep disorders have on cognition in both Parkinson's disease and REM sleep behaviour disorder.