Sleep abnormality is a prevalent but under-recognized symptom affecting patients with various neurodegenerative diseases including Alzheimer's disease (AD) and Parkinson's disease (PD) from the early stage of the diseases. Sleep abnormality of these patients was conventionally attributed to AD or PD pathology that affects the brain regions regulating sleep-wake or circadian rhythm. On the contrary, various epidemiological studies have demonstrated the association of sleep abnormality with an increased risk of AD or PD. However, relevant disease models to prove the causal relationship between sleep abnormality and neurodegenerative diseases were lacking.
We recently succeeded in inducing chronic sleep abnormality closely resembling that of AD patients in AD model mice and revealed that chronic sleep fragmentation, a specific subtype of sleep abnormality frequently observed in the patients of neurodegenerative diseases, indeed exacerbates AD pathology in the mice brain. Our findings are in accord with previous epidemiological studies in humans and thus would contribute to the understanding of the underlying pathomechanisms and informing the development of disease-modifying therapy for neurodegenerative diseases.