Carolien Zeetsen

61 CHAPTER Prevalence of cognitive i mpairments in patients with SUD 4 Introduction Substance use disorder (SUD) refers to ‘a cluster of cognitive, behavioural and physiological symptoms indicating that the individual continues using the substance despite significant substance–related problems’ (APA, 2013, p. 483). Substances like alcohol, cannabis, stimulants and opioids are psychoactive drugs that may change brain function and structure after chronic use, and result in cognitive and behavioural deficits that remain even after detoxification. The prevalence of cognitive impairments in patients with SUD is still unclear (Toledo–Fernández et al., 2018) and is estimated between 30% and 80% (Copersino et al., 2009). This wide range includes, for instance, differences in the mode of action between substances, years and amount of regular use, and effects of sex. As each substance has different effects on brain functioning the consequences of prolonged substance use, such as cognitive impairments, will also differ between substances. Acute alcohol intoxication primarily acts upon cognitive functions associated with the prefrontal cortex, such as planning, verbal fluency, memory and complex motor control (Peterson et al., 1990; Lyvers et al., 2010). The effects of alcohol on cognitive functioning post–detoxification are found to affect all cognitive domains (Stavro et al., 2013). After one to three weeks of abstinence, chronic alcohol use is still associated with decrements in memory, visuospatial abilities and inhibition (van Holst et al., 2011). After six months of abstinence, cognitive recovery generally has occurred (Pitel et al., 2009) but impairments have still been demonstrated in the domains of visuospatial abilities and decision making (Fernández–Serrano et al., 2011) which may last at least up to one year after abstinence (van Holst et al., 2011; Stavro et al., 2013). There is some evidence that in the long term, the cognitive consequences of alcohol use disorder (AUD) may be fully reversible (Arts et al., 2017), but cases of persistent cognitive impairments like Korsakoff’s syndrome are not uncommon (Bowden, 1992). The acute consequences of cannabis intoxication primarily involve working memory, executive functioning and attention (Lundqvist, 2005). Post–detoxification effects have been found to impact executive functioning after 17 hours until up to 21 days of abstinence (Pope Jr et al., 2001; Solowij et al., 2002; Crean et al., 2011). In the long term (i.e. after more than one month of abstinence), full cognitive recovery can occur (Pope Jr et al., 2001; van Holst et al., 2011; Gonzalez et al., 2017). Concerning stimulant abuse, including cocaine, amphetamine and ecstasy, cognitive impairments are considered relatively mild (Goldstein et al., 2004) and seem to follow an inverted U–shape (Wood et al., 2014). Acute intoxication with low doses has mostly enhancing effects on response inhibition, attentiveness, speed and psychomotor