Adolescent cannabis use, change in neurocognitive function, and high-school graduation: A longitudinal study from early adolescence to young adulthood

Abstract

The main objective of this prospective longitudinal study was to investigate bidirectional associations between adolescent cannabis use (CU) and neurocognitive performance in a community sample of 294 young men from ages 13 to 20 years. The results showed that in early adolescence, and prior to initiation to CU, poor short-term and working memory, but high verbal IQ, were associated with earlier age of onset of CU. In turn, age of CU onset and CU frequency across adolescence were associated with (a) specific neurocognitive decline in verbal IQ and executive function tasks tapping trial and error learning and reward processing by early adulthood and (b) lower rates of high-school graduation. The association between CU onset and change in neurocognitive function, however, was found to be accounted for by CU frequency. Whereas the link between CU frequency across adolescence and change in verbal IQ was explained (mediated) by high school graduation, the link between CU frequency and tasks tapping trial and error learning were independent from high school graduation, concurrent cannabis and other substance use, adolescent alcohol use, and externalizing behaviors. Findings support prevention efforts aimed at delaying onset and reducing frequency of CU.

Figure 1

Unconditional latent growth model of self-reported cannabis use frequency from 14 to 17 years (a) centered at 14 years and (b) the average cannabis use frequency across adolescence. As depicted by the growth factor (slope) loadings (0, 1, 2, 2.4), frequency of cannabis use increased steadily (linearly) from 14 to 16 years with the increase becoming flatter from 16 to 17 years. Can, Cannabis; r, residual variance.

Figure 2

Change in response perseveration (card playing task) and working memory, planning, and trial and error learning (conditional association task) from early adolescence to early adulthood by adolescent cannabis use scores. In the card playing task, playing more than 75 cards is considered response perseveration (Séguin et al., 2002). Cond Association, conditional association task.