This is the protocol for a review and there is no abstract. The objectives are as follows: To determine the cross-sectional diagnostic accuracy of [index test] at various thresholds for ADD and other dementias [target condition] in [target population].ORTo determine the accuracy of [index test] at various thresholds for diagnosing ADD and other dementias [target condition] in [target population] after a follow-up period (delayed-verification studies).To investigate the heterogeneity of test accuracy in the included studies.To highlight the quality and quantity of research evidence available on the effectiveness of the index test in the target population.To identify gaps in the evidence and determine where further research is required.