2.2. Cognitive tests: A comprehensive battery of tests encompassing the cognitive domains of executive function, attention, memory, perception, and general intellect is administered twice at baseline and at the end of 16-week treatment by a trained psychologist. Scoring follows standardized procedures. The Wisconsin Card Sorting Test (WCST) (Heaton et al, 1993) is administered as a measure of executive function. The N-back (0-3 back) test is administered as a measure of working memory. Logical Memory I and II, Verbal Paired Associates I and II, Visual Reproduction I and II and Digits Forward from the Wechsler Memory Scale-Revised (WMS-R) (Wechsler, 1987) are administered as a tests of episodic memory. The Distractibility version of Gordon Continuous Performance Test (CPT)is administered as a test of attention. A four-subtest version of the Wechsler Adult Intelligence Scale-Revised (WAIS-R), (Wechsler, 1981; Missar et al, 1994) consisting of the Arithmetic, Similarities, Picture Completion, and Digit Symbol Substitution tests is administered to obtain an estimate of current Full-Scale Intelligence Quotient (FSIQ).