Digital biomarkers in early Alzheimer's disease from wearable or portable technology: A scoping review

The pursuit of accurate biomarkers for early detection and disease monitoring of Alzheimer's disease (AD) has driven a growing interest in digital biomarkers. We aimed to map the research landscape of digital biomarkers in early AD obtained with wearable or portable digital health technologies (DHTs).

In our scoping review, we included original research on portable or wearable DHTs where digital biomarkers were measured in populations of early AD (mild cognitive impairment (MCI) or mild dementia). We searched MEDLINE, Web of Science and EMBASE with a wide search strategy with independent review and data extraction by two review team members. We charted data in tabular/graphical form.

After deduplication and screening of 8893 records, we included 109 studies describing a wide array of wearable or portable DHTs that obtained digital biomarkers. The study population consisted of 3019 individuals with MCI due to AD (54 % female, weighted mean age 73 years), and 1942 individuals with mild AD (55 % female, weighted mean age 73 years). The most studied biomarkers were rest/activity (39 %), speech (17 %), and gait (14 %), with most studies focusing on one domain. Few studies reported outcomes associated with diagnosis (16 %) and prognosis (3 %).

We identified a growing evidence base investigating digital biomarkers in early AD. There is a paucity of studies examining diagnostic and prognostic properties, representing a knowledge gap. This overview may help to guide future research efforts to bridge the gap between the development and clinical implementation of digital biomarkers in early Alzheimer's disease.