Biological basis for sleep disturbance and behavioral symptoms in dementia: a biobehavioral model

Behavioral symptoms and sleep disturbance occur in more than 56% of older adults with mild to moderate dementia and are challenging and costly. This article proposes a biobehavioral causal model to explain sleep disturbances and behavioral symptoms in dementia (BSD) based on an integrative science perspective using the life cycle model of stress (chronic stress) integrating genetic, neuroendocrine, and personality factors. The model proposes that: (a) BSD are an outcome of sleep disturbance; (b) hypothalamic-pituitary-adrenal (HPA) axis dysregulation is key to sleep disturbances and BSD; (c) genotype influences response to stress hormones; (d) HPA is influenced by genotype; (e) trait anxiety moderates the relationship between HPA axis and BSD and/or sleep disturbances; and (f) trait anxiety is influenced by genotype. Examining these relationships simultaneously will advance our theoretical understanding of BSD and sleep disturbances, potentially providing a basis for the design of targeted interventions and prevention strategies with an understanding of risk.