Failure to sustain prepulse inhibition in adolescent marijuana users

Abstract

BackgroundMarijuana use is typically initiated during adolescence, which is a critical period for neural development. Studies have reported reductions in prepulse inhibition (PPI) among adults who use marijuana chronically, although no human studies have been conducted during the critical adolescent period. MethodsThis study tested PPI of acoustic startle among adolescents who were either frequent marijuana users or naïve to the drug (Controls). Adolescents were tested using two intensities of prepulses (70 and 85dB) combined with a 105dB startle stimulus, delivered across two testing blocks. ResultsThere was a significant interaction of group by block for PPI; marijuana users experienced a greater decline in the PPI across the testing session than Controls. The change in PPI of response magnitude for users was predicted by change in urine THC/creatinine after atleast 18h of abstinence, the number of joints used during the previous week before testing, as well as self-reported DSM-IV symptoms of marijuana tolerance, and time spent using marijuana rather than participating in other activities. ConclusionsThese outcomes suggest that adolescents who are frequent marijuana users have problems maintaining prepulse inhibition, possibly due to lower quality of information processing or sustained attention, both of may contribute to continued marijuana use as well as attrition from marijuana treatment.