“…As described previously [21], the cognitive assessment included four subdomains: Raven's Progressive Matrices-R, which measures nonverbal abstract reasoning and visual-spatial problem-solving abilities; Similarities-R, which assesses verbal abstraction and categorization; Otis-R, verbal comprehension, which assess the ability to understand and carry out verbal instructions; and Arithmetic-R, which assesses mathematical reasoning, concept manipulation and concentration [13]. The sum of the scores of all four tests constitutes a validated global score of overall intelligence [14]. Scored on a 90point scale, this overall score has demonstrated high correlation (r>0.8) with the Wechsler Adult Intelligence Scale (WAIS) total intelligence quotient (IQ) [13,14].…”