“…Importantly, however, duration, quantity, and frequency of use, as well as polysubstance abuse, are associated with pronounced impairments (Lundqvist, 2009;Schrimser et al;Zinn et al, 2004). It also should be acknowledged that individuals with a history of substance abuse have a high prevalence of traumatic brain injury, which might impair neuropsychological functions (Kelly, Johnson, Knoller, Drubach, & Winslow, 1997;Lange, Iverson, & Franzen, 2008;Morris & Lawson, 1999). In other words, assessment of neuropsychological functions is preferably regarded as a complex process in which a variety of factors and circumstances have to be considered (Lundqvist, 1995;Prosser et al, 2008).…”