Given the lack of comprehensive neuropsychological tools and neuropsychological services in Sub-Saharan Africa (SSA), cognitive screeners for dementia can be useful tools to screen for suspected dementia at the population level. However, most available screeners have not been developed or validated in SSA populations. The Community Screening Instrument for Dementia (CSID) was developed for cross-cultural use, and it has a cognitive testing component and informant interview. We have previously demonstrated that lower years of education and female sex are associated with lower scores on the CSID. Here, we examine the utility of demographically adjusted CSID scores in a community sample of Congolese older adults.

354 participants (mean age=73.6±6.7, mean education (years) =7.3±4.7; 50% female) were randomly recruited in Kinshasa, Democratic Republic of the Congo, and completed the CSID and the Alzheimer's Questionnaire (AQ) to examine functional abilities. Raw scores were demographically adjusted for education and sex by adding 1 point for <12 years of education and 1 point for female. Cognitive impairment was classified as a total score below 25.5. Rates of impairment were compared between raw scores and demographically-adjusted scores. Demographic profiles were examined between both classifications

Average raw CSID scores were 25.23 (SD=4.19) and average demographically-adjusted scores were 26.59 (SD= 4.09). Approximately 43.1% of the sample was impaired based on the raw CSID scores compared to 30.4% with the demographically-adjusted scores (x2= 12.334, p<.001). There was a higher proportion of females (n=95; 26.8%) classified as impaired with the raw SCID scores compared to the demographically-adjusted scores (n=62; 17.5%; x2= 8.87, p=0.003). Approximately 27.4% (n=97) of the participants classified as impaired with the raw SCID scores had primary education or less (i.e., 1-6 years) compared to 18.9% with the demographically-adjusted scores (n=67; (x2= 107.77, p<.001). Forty-five participants were re-classified as not impaired with the demographically-adjusted scores with the majority of these participants being female (73.3%), having primary education (66.7%), and being functionally unimpaired on the AQ (91.1% unimpaired).

We demonstrate that raw scores on the CSID can lead to misclassification of impairment in females and in individuals with lower years of education. Demographically-adjusted scores on the CSID can help properly capture those with suspected dementia while reducing false positives. Given the effects of education and sex on performance, future studies should examine if demographically adjusted scores improve the sensitivity and specificity of the CSID in Congolese populations and compare its performance to other screening tools to determine the most appropriate screener for this population.

With participant recruitment being a top barrier to AD research progress, the rate of screen failure in Alzheimer’s disease (AD) clinical trials is unsustainable. Although steps have been undertaken to consider solutions to the continued recruitment shortage, there is unfortunately minimal emphasis on reducing screen failure rates based on study inclusion criteria. Here we present information attempting to understand the cognitive, emotional, and functional features of individuals who failed screening measures for AD trials.

The current study is a retrospective, cross-sectional analysis. Thirty-eight participants (aged 50-83) having (1) previously received a clinical diagnostic workup at a transdisciplinary cognitive specialty clinic and (2) previously screened for a specific industry-sponsored clinical trial of MCI/early AD (EMERGE) met inclusion criteria. Previously collected clinical data were analyzed to identify predictors of AD trial screen pass/fail status.

Of the 38 participants in the current study, 14 screen passed into this AD clinical trial, and 24 screen failed. Higher screen failure rates were significantly related to gender, with 83% of female participants screen failing this AD trial versus 45% of male participants. There was no difference in age or education between screen pass/fail groups, nor were differences present for performance on visual or verbal memory tasks, or the MOCA. Conversely, those participants screen failing this AD clinical trial performed significantly worse on nonmemory cognitive domains pertaining to general fund of knowledge, working memory, and executive functioning. Additionally, the screen fail group reported greater levels of anxiety, but not depression nor endorsements on a measure of functional status.

Worse performance on non-memory neuropsychological domains was related to screen failure status for the EMERGE AD clinical trial. This finding may be explained by the traditional recruitment pathway from clinic to trials, which beyond the diagnosis of interest is up to the opinion of the physician to determine “fit” for a trial. Higher screen failure rates may result from physicians erroneously viewing more globally-impaired patients as being more appropriate for an AD clinical trial, resulting in greater tendencies towards recruiting patients who are too severe to meet inclusion criteria for a trial. Recruiting patients into clinical trials earlier in their disease course - when disease severity is less - may result in reduced screen failure rates in AD trials. That we could not detect a relationship between memory-related tasks and screen fail/pass status may be explained by either (1) the measures used in the EMERGE trial were not as sensitive to subtle changes in memory, or (2) that memory dysfunction is necessary for a diagnosis of AD but not sufficient to distinguish who will be successfully screened into an AD clinical trial. Overall, these findings have the potential to advance the field by reducing screen failure rates in AD clinical trials by using information already available to clinical trial teams, which will enhance trial-recruitment infrastructure and encourage greater engagement of older adults in AD research.