Longitudinal association between daytime sleepiness and cognitive decline in dementia: A study protocol

INTRODUCTION: Dementia is a major cause of disability worldwide. About 25%-40% of patients with mild to moderate dementia are affected by sleep-awake cycle disturbances, including increased daytime sleepiness and insomnia. However, little is known about the specific impact of excessive daytime sleepiness on the cognitive decline of dementia patients. OBJECTIVES: To evaluate the impact of daytime sleepiness on the cognitive decline of dementia patients. Additionally, longitudinal associations with functional impairment and neuropsychiatric symptoms will be explored. METHODS: A longitudinal study will be conducted in a psychogeriatric consultation. Patients will be consecutively invited according to predefined eligibility criteria. Those aged ≥65 years, with dementia diagnosis or Mini-Mental State Examination (MMSE) <24, and with a knowledgeable caregiver, will be included. The exclusion criteria are: a caregiver <18 years, terminally ill, incapable to communicate or with a known diagnosis of insomnia, sleep related respiratory disorders, central hyperinsomnia, restless legs syndrome or sleep paralysis. Participants will undergo an assessment with a comprehensive protocol including: Montreal Cognitive Assessment (MoCA), Barthel and Lawton Index, Epworth Sleepiness Scale (ESS), Neuropsychiatric Inventory (NPI) and Global Deterioration Scale (GDS). Participants will be re-assessed 6 months after the initial evaluation. The Health Ethics Committee of Hospital Universitário de São João granted the study authorization (nº 260/2020). RESULTS: Findings will be disseminated via publication in peer-reviewed journals and presentations at national and international scientific conferences. CONCLUSIONS: This study will address key questions on the relation of daytime sleepiness and dementia outcomes, in order to undertake corrective and preventive non-pharmacological and pharmacological approaches.