The usability and reliability of a smartphone application for monitoring future dementia risk in ageing UK adults.

BACKGROUND: The rising number of dementia diagnoses and imminent adoption of disease-modifying treatments necessitate innovative approaches to identify individuals at risk, monitor disease course and intervene non-pharmacologically earlier in the disease course. Digital assessments of dementia risk and cognitive function have the potential to outperform traditional in-person assessments in terms of their affordability, accuracy and longitudinal tracking abilities. However, their accessibility and reliability in older adults is unclear. AIMS: To evaluate the usability and reliability of a smartphone assessment of lifestyle and cognitive factors relevant to dementia risk in a group of UK-based older adults. METHOD: Cognitively healthy adults (n = 756) recruited through the Dementias Platform UK Great Minds volunteer register completed three assessments of cognitive function and dementia risk over a 3-month period and provided usability feedback on the Five Lives smartphone application (app). We evaluated cognitive test scores for age, gender and higher education effects, normality distributions, test-retest reliability and their relationship with participants' lifestyle dementia risk factors. RESULTS: Participants found the app 'easy to use', 'quick to complete' and 'enjoyable'. The cognitive tests showed normal or near-to-normal distributions, variable test-retest reliabilities and age-related effects. Only tests of verbal ability showed gender and education effects. The cognitive tests did not correlate with lifestyle dementia risk scores. CONCLUSIONS: The Five Lives assessment demonstrates high usability and reliability among older adults. These findings highlight the potential of digital assessments in dementia research and clinical practice, enabling improved accessibility and better monitoring of cognitive health on a larger scale than traditional in-person assessments.

VTA dopamine neuron activity encodes social interaction and promotes reinforcement learning through social prediction error.

Social interactions are motivated behaviors that, in many species, facilitate learning. However, how the brain encodes the reinforcing properties of social interactions remains unclear. In this study, using in vivo recording in freely moving mice, we show that dopamine (DA) neurons of the ventral tegmental area (VTA) increase their activity during interactions with an unfamiliar conspecific and display heterogeneous responses. Using a social instrumental task, we then show that VTA DA neuron activity encodes social prediction error and drives social reinforcement learning. Thus, our findings suggest that VTA DA neurons are a neural substrate for a social learning signal that drives motivated behavior.