Carolien Zeetsen

72 Table 4.2. Mean ( SD ) Montreal Cognitive Assessment (MoCA) domain (MoCA–DS) and total scores (MoCA–TS) for the total sample and per primary–problem substance. Post–hoc gives a description of significant differences. MoCA–DS (score range) Total Alcohol (A) Cannabis (C) ( n = 656) ( n = 391) ( n = 123) Executive functioning (0–2) 1.31 (0.67) 1.27 (0.68) 1.45 (0.66) Visuospatial abilities (0–4) 2.77 (0.94) 2.73 (0.95) 2.91 (0.90) Attention (0–6) 5.40 (0.97) 5.44 (0.95) 5.42 (0.92) Language (0–5) 4.46 (0.72) 4.44 (0.76) 4.48 (0.67) Abstract reasoning (0–2) 1.52 (0.63) 1.51 (0.64) 1.58 (0.60) Memory (0–5) 3.30 (1.49) 3.21 (1.56) 3.65 (1.24) Orientation (0–6) 5.75 (0.61) 5.76 (0.62) 5.74 (0.54) MoCA– TS (0–30) 25.52 (3.12) 25.30 (3.23) 26.33 (2.69) n (%) scoring < 25 206 (31) 134 (34) 26 (21) Note: patients with sedatives or gamma–hydroxybutyrate (GHB) as the primary–problem substance are only included in the total sample and not separately described. Factors related to cognitive performance In the total sample, the MoCA–TS was negatively correlated with age ( r = −0.28, p < 0.001), with a shared variance of only 9%. None of the other investigated factors (i.e. years of regular use, abstinence duration, severity of dependence and/or abuse, depression, anxiety and stress) were significantly correlated with the MoCA–TS. Abstinence and polysubstance use were also not related to the MoCA–TS (all p –values > 0.05). Since age was significantly correlated with MoCA–TS in the total sample and there was a significant difference in mean age between substances, the correlation between MoCA–TS and age was calculated per primary–problem substance. For alcohol age was negatively correlated with MoCA–TS ( ρ = −0.331, p < .001), for cannabis this negative correlation was marginally significant ( ρ = −0.148, p = .051), for stimulants age was positively correlated with MoCA–TS ( ρ = 0.173, p = .042), and the correlation between age and MoCA–TS for opioids was negative but not significant ( r = −0.195, p = .170).