• To determine the cross-sectional diagnostic accuracy of [index test] at various thresholds for ADD and other dementias [target condition] in [target population].

OR

• To 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.