3.1 Demographic and clinical characteristics
Four values of years of regular use and age of onset were missing. These missing data have been imputed based on the regression between age and years of regular use / onset age of regular use in males and females, separately. The following formula were used for years of regular used: -4,11 + (0,31*age) for males and 10,62 + (0,6*age) for females. For onset age of regular use the following formula were used: 4,11+ (0,69*age) for males and 10,63 + (0,4*age) for females.
The CU and non-CU groups were matched on age. Yet, the CU group reported significantly higher scores on ADHD symptom severity, depressive symptoms, impulsivity, childhood trauma and drinking severity. Moreover, there was a sex by group interaction effect in childhood trauma, depressive symptoms and impulsivity, where female CUs reported significantly higher scores. Within the non-CU group, there were no sex differences in these variables. Accordingly, these clinical characteristics have been included as potential confounders in exploratory analyses of the cocaine and emotional cue-reactivity data. Male and female CUs were well matched on cocaine use severity, cocaine use per month, and years of regular use. However, females reported regular use of cocaine at an earlier age than males. An overview of all demographic and clinical data and statistics are presented in Table 1 and 2.