comprised of Wisconsin Card Sorting Test (WCST) number of categories attained, WCST number of perseverative errors, Shipley Institute of Living Scale abstractions subtest, WAIS-R Comprehension, Similarities, Picture Completion and Picture Arrangement subtests. Prior to deriving cognitive domain scores, raw test score from each neuropsychological test variable was converted to a z score (Mean=0, SD=1) based on norms established using 382 healthy volunteers. Scores were reversed where necessary. A larger negative score indicates poorer performance below the mean. Using these z scores, each domain score is the summed average of its component neuropsychological test variables.
