sentence: Studies conducted in other substance using populations ( e.g ., alcohol , cannabis , cocaine , opioid ) have identified associations with demographics ( e.g ., older age , higher education ) , motivation ( e.g ., desire to quit ) , coping style , depressive symptoms , neurocognitive functioning , and other substance use-related factors ( e.g ., degree / recency of use , prior treatment outcomes ; Demmel and Rist , 2005 , Demmel et al ., 2006 , Demmel , 2004 , Dolan et al ., 2008 , Greenfield , 2012 , Ilgen et al ., 2007 , Majer , 2003 ) .