Alzheimer's disease and related dementias (ADRD), including mild cognitive impairment (MCI), are becoming among the most prevalent causes of disability, death and healthcare costs worldwide. Sleep and circadian rhythm disturbances are common among individuals with MCI as well as their spouses/ partners and may increase risk of the development of ADRD in both patients and partners. This is the first study to systematically investigate sleep as a shared health behavior within couples in which one member has MCI, and the degree to which sleep and circadian disturbances impact both partners health and well-being, including cognitive decline and risk for ADRD.

Individuals with mild cognitive impairment (MCI) demonstrate cognitive decline without major functional impairment but also experience a 7-fold increased risk for developing Alzheimer's disease, a leading cause of poorer quality of life (QOL), premature mortality, and health care expenditures. Sleep and biobehavioral rhythm disturbances (disruptions in 24h oscillations in physiology and behavior, including rest-activity patterns and mealtimes) are more than twice as common among patients with MCI than cognitively intact older adults. Emerging evidence demonstrates a mechanistic role of sleep and biobehavioral rhythm disturbances in cognitive decline and the development and progression of Alzheimer's disease. Importantly, the consequences of sleep and biobehavioral rhythm disruption in MCI extend beyond the patient, also affecting the spouse/partner, as sleep is a "shared" health behavior for most adults. However, sleep and biobehavioral rhythms are typically considered at the level of the individual.

The overall goal of the study is to investigate sleep and biobehavioral rhythms as fundamental dyadic processes that contribute to the health and cognitive functioning of individuals with MCI or mild AD and their partners. The project will evaluate the daily and longitudinal effects of two dyadic processes in sleep:interdependence (partners' sleep patterns influence on each other) and concordance (i.e., the couples' similarity in rest/activity and social rhythms such as meal timing). The protocol involves a 14-day naturalistic study protocol in order to examine the mechanistic associations between sleep and biobehavioral rhythms and proximal indicators of daytime functioning, within a sample of 170 couples in which one partner evidences cognitive impairment (MCI to mild Alzheimer's disease). During the naturalistic study protocol, measures will capture sleep and biobehavioral rhythms via objective (actigraphy) measures of sleep and circadian rest-activity rhythms and daily social rhythms, respectively. Also, measures include daily assessments of mood and relationship quality and an an innovative smartphone cognitive assessment that has been validated to measure cognitive function in daily life. The longitudinal assessment will include comprehensive neuropsychological assessments at baseline and again at two-year follow-up to examine how sleep and biobehavioral rhythm disruptions at baseline predict cognitive decline over 2 years in both partners.

Results of study will advance the understanding of the daily and longitudinal relationships between the individual and couple-level processes in sleep and biobehavioral rhythms that influence the progression of cognitive decline in a population at increased risk for developing Alzheimer's disease.

Inclusion Criteria:

• Married or partnered in a romantic relationship, cohabiting for at least two years
• age >50
• smartphone user
• one partner meets criteria for cognitive impairment without severe impairment in daytime dysfunction according to telephone screening, while other partner must not meet this criteria for impairment.

Exclusion Criteria:

• Unstable or severe medical or psychiatric conditions that would interfere with study participation (including but not limited to current cancer treatment, psychosis, history of major stroke, head injury with loss of consciousness >30 min, other neurologic/systemic illness that may affect cognition, alcohol or other substance abuse)
• current use of antipsychotic or anticonvulsant medications
• inadequate vision, hearing, or dexterity to participate in the assessment
• night shift work >1x per month (defined as beginning work after 9:00 pm or work in the overnight hours [12:00 am-5:00 am])

Participants will be married or cohabiting couples recruited from community locations in the United States who meet the study criteria.

Data available upon request.