Norms for change in episodic memory as a prerequisite for the diagnosis of mild cognitive impairment (MCI).

The new diagnostic criteria for mild cognitive impairment (MCI) from the International Working Group on Mild Cognitive Impairment (Winblad et al., 2004, p. 243) list "evidence of decline over time in objective cognitive tasks" as one diagnostic sign, implying the repeated neuropsychological testing. This study aimed to compare different assessment methods of longitudinal change based on the performances of 366 cognitively healthy participants (237 men, 129 women) examined with a German version of the California Verbal Learning Test (Delis, Kramer, Kaplan, & Ober, 1987) at baseline and 2 years later. Age, education, gender, and baseline performance were taken into account. Results revealed marked practice effects after 2 years. Normal ranges for change that controls for practice effects and regression to the mean proved to be superior to other reliable change indexes. This new method allows for more valid interpretation of change in neuropsychological functioning and thus diagnosis of MCI.