Derived trail making test indices in a sample of marijuana abusers: Demographic effects

Derived indices on the Trail Making Test (TMT), a test often used for screening for cognitive impairment, were examined in a sample of marijuana abusers in drug abuse treatment programs. A mixed-race sample of 259 subjects was drawn from electronic files of data from the Drug Abuse Treatment Outcome Study (DATOS). The DATOS was a naturalistic, prospective cohort study that collected data from 1991 to 1993 in 96 programs in 11 cities in the United States. Data were analyzed to determine the effects of demographic variables on derived indices created by adding, subtracting, multiplying, and dividing Parts A and B of the TMT in this large treatment sample of marijuana abusers. The variables of age, ethnicity, and education were statistically significant for the total (A + B), and interaction (A x B/100) derived indices of the TMT. The difference score (B - A) was significant only for ethnicity and the ratio score (B/A) was not significant for any demographic variable.