The effect of the lockdown during the COVID‐19 pandemic on the risk of developing dementia; A cohort study

Abstract Background Increased social activity, relationships and being cognitively active have been associated with decreased risk of dementia. The COVID‐19 pandemic has significantly influenced these and increased the feeling of loneliness throughout society. Protective measures against the virus, such as social distancing and isolation, were enforced to reduce contact between people. We hypothesised that this would lead to an increased risk of transition to dementia. Method We obtained data from the Brains for Dementia (BDR) cohort, which has been collecting roughly annual data on 3,726 older adults with and without dementia since 2008. Data continued to be collected during the lockdowns, although by telephone and /or video call instead of in person. Individuals diagnosed with dementia at study entry were excluded from this study as were individuals with only one visit. Cognitive status was classified using the CDR global score. Poisson regression with cubic splines to account for differences in age was used to compare the rate ratio of developing dementia before/after March 1 st 2020. Result Out of 2,242 individuals, 205 individuals developed dementia before and 40 developed dementia after 1/3/20. The rate ratio of developing dementia after 1/3/20 was 0.770 (95% CI 0.438 – 1.356, p = 0.366) but there was evidence that this differed with age. Conclusion The chance of individuals developing dementia did not change significantly after the first lockdown, although power was low. We will now perform sensitivity analyses to assess whether the type of assessment or using the CDR sum of boxes/MMSE to define cognitive status alters this relationship.