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The Cognitive Online Self-Test Amsterdam (COST-A): Establishing norm scores in a community-dwelling population
Leonie N C Visser1,2, Mark A Dubbelman1, Merike Verrijp1
1Alzheimer Center Amsterdam Department of Neurology Amsterdam Neuroscience Amsterdam UMC VU University Medical Center Amsterdam the Netherlands.
Background:
Heightened public awareness about Alzheimer's disease and dementia increases the need for at-home cognitive self-testing. We offered Cognitive Online Self-Test Amsterdam (COST-A) to independent groups of cognitively normal adults and investigated the robustness of a norm-score formula and cutoff.
Methods:
Three thousand eighty-eight participants (mean age ± standard deviation = 61 ± 12 years, 70% female) completed COST-A and evaluated it. Demographically adjusted norm scores were the difference between expected COST-A scores, based on age, gender, and education, and actual scores. We applied the resulting norm-score formula to two independent cohorts.
Results:
Participants evaluated COST-A to be of adequate difficulty and duration. Our norm-score formula was shown to be robust: ≈8% of participants in two cognitively normal cohorts had abnormal scores. A cutoff of -1.5 standard deviations proved optimal for distinguishing normal from impaired cognition.
Conclusion:
With robust norm scores, COST-A is a promising new tool for research and clinical practice, providing low cost and minimally invasive remote assessment of cognitive functioning.
