OBJECTIVES : Alzheimer's disease (AD) represents a major humanistic and economic burden worldwide. Effective strategies to prevent, delay, or treat the disease are unavailable, and current treatments offer only moderate symptom relief. Early detection and monitoring of pre-symptomatic AD – when treatment benefit might be greatest – are crucial. There is increasing interest in using digital technologies, including mobile and wearable devices, to identify early functional impairments in AD. We aimed to systematically review recent evidence to assess the place of these technologies in AD research.

METHODS : Following PRISMA guidance, we searched MEDLINE and Embase for observational studies (published from January 2014–May 2019) on digital technologies used to measure functional outcomes in AD. A protocol guided study selection. For included studies, reported data on the types of technology, functional outcomes, and study design were extracted into a pre-designed form and summarized qualitatively.

RESULTS : The search retrieved 532 articles. Of the 31 studies included, most used digital technologies to assess gait function (with accelerometers or body-worn sensors; n=12) and sleep-wake or physical-activity patterns (with wrist-worn actigraphs; n=11). The technologies captured additional data (e.g., three-dimensional gait analysis, gait symmetry and regularity, rest-activity rhythm fragmentation) that aided assessment of mild cognitive impairment (MCI) progressing to AD. Eight studies described using remote digital technologies to assess driving, mobility, or computer-use patterns, which were significantly impaired in preclinical AD and MCI compared to normal ageing.

CONCLUSIONS : Using digital technologies in AD research remains developmental. Gait monitoring has been the most active area of research and might allow detection of those at risk of developing AD. Real-world data from digital technologies may increase the quality and completeness of evidence and patient acceptance. Further research is needed to validate digital technologies in early AD detection and enable their integration in clinical trials.