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30 March 2021

Engagement and Adherence to Remote Testing in Middle-Aged Adults at Risk of Dementia

At the virtual ADPD 2021 event, Emily Thorp discussed engagement and adherence to remote testing in middle-aged adults at risk of dementia.

Remote testing solutions most commonly involve participants completing assessments via an online platform in the comfort of their home, on their own device. Conducting trials in this way can often improve study efficiency by reducing the time and costs required to collect large volumes of reliable data. During the COVID-19 global pandemic, these methods have become increasingly popular as they have allowed research to continue uninterrupted. They have also encouraged organisations to switch to a more patient-centric approach for data collection, which increases accessibility of volunteers to trials meaning more people are able to participate.


The COVID-19 pandemic has accelerated the need for digital solutions to allow Alzheimer’s research to continue, albeit in a modified form. Remote administration platforms are powerful tools that can enable rapid, cost-effective assessments to be conducted by participants from their own homes.

Using data collected through the Healthy Brain Project, an online study of at-risk middle-aged adults, we aimed to describe demographic, motivational and adherence characteristics of participants who completed CANTAB Paired Associates Learning (PAL) assessments unsupervised, within their own homes.


  • The Healthy Brain Project aims to understand how genes may influence the risk for developing diseases, such as Alzheimer’s disease, depression, and post-traumatic stress disorder
  • The project hopes to gather a comprehensive amount of information from 10,000 volunteers and has currently collected baseline data from over 7,000 volunteers


  • Participants complete assessments remotely on their own devices via the Healthy Brain Project Portal
  • The study asks each participant to complete a number of assessments each year for at least five years. Due to the large volume of data that is being collected, participants are given a 6-month window in which to complete all sections
  • These assessments include lifestyle, mood, personality, medical history and demographic questionnaires, as well as a number of cognitive assessments including CANTAB’s Paired Associates Learning (PAL) task, a sensitive measure of episodic memory


To better examine participant's engagement and adherence to remote testing, we categorised participants into two groups based on whether they had yet completed multiple assessments or not. From the current enrolment of 7,000, just over 4,300 subjects have completed assessments at multiple timepoints.

Initial analysis included examining participant’s engagement with the sessions and it was found that over 96% of participants who had chosen to complete CANTAB’s PAL had complete the session in full. We then grouped the participants who had completed multiple timepoints into groups based on how many visits they had completed, as well as calculating an average time between assessments for each participant to examine their adherence to the testing protocol.

Unpublished data collected through the Healthy Brain Project

The density plots above show the distribution of the average testing interval, in days, between groups. These show that the majority of participants did complete the assessments on average around 365 days apart, as instructed. However, it is also shown that there are much higher levels of variation in average testing interval in those subjects who have only completed assessments at 2 or 3 time points, compared to those who have completed 4 visits. Due to the fact that participants are given 6 months to complete the assessments, it can also be seen that there are a large number of participants who are completing the assessments, on average, either side of the 365 days expected average, between 6 months (183 days) and 18 months (548 days) apart.

Unpublished data collected through the Healthy Brain Project

In order to better understand this, average testing interval was plotted regardless of the number of visits completed. Any subjects who completed the assessments as per the study protocol are represented within the two blue lines, and the majority of participants do fall within this group. However, this is a very apparent number of participants who appear to have completed the assessments in quick succession, as shown by the cluster on the far left-hand side of the above graph. We can also see another cluster of participants at around 700 – 750 days, which represents a group with an average testing interval of around 2 years. This is likely to represent a small group, around 1.5% of subjects, who missed a time point, and then completed the subsequent assessment as expected. This figure is promising and shows good adherence to remote testing practices in an at-risk, middle-aged population.


Overall, participants adhered well to the study protocol and appear to be engaged with the remote testing procedures. Over 96% of PAL sessions that were started by participants were fully completed.

There is little difference in memory performance between all groups, and the mean time between visits does not appear to relate to the level of cognitive impairment. However, there appear to be slight differences in terms of memory scores between the group who repeat the assessments almost immediately (<7 Days), and those who complete the assessments shortly after (<6 Months). 

Next Steps

​The next steps include an analysis of longitudinal PAL scores to determine whether these relate to adherence to the study protocol as well as further expanding this exploration to assess other measures, such as personality traits and anxiety levels, and their relationship to participant's adherence and engagement to remote testing.

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Tags : cantab | cognitive testing | cognition | digital tools | web-based testing | pal | dementia

Author portrait

Operational Scientist, Cambridge Cognition - Emily Thorp