Table 1.

Summary of major findings of effects of cannabis and alcohol on developing, adolescent brain

	Neuropsychological	Neuroanatomical	Neurotransmitter	Brain response
Cannabis	- ⬇ performance in attention, memory, processing speed, and visuospatial functioning; decreased processing speed and executive function (Jacobus et al. 2015) - ⬇ psychomotor processing, attention, story memory, and planning and sequencing ability; with abstinence, subtle neuropsychological deficits remained [22] - ⬇verbal learning and working memory improved following 3 weeks of abstinence whereas attention deficits remained [23]	- ⬆ thickness of cortices in left entorhinal cortex; thinner temporal and frontal cortices (Jacobus et al. 2014) - ⬇hippocampal, prefrontal cortex, and amygdala volumes and larger cerebellum and striatum volumes (Lorenzetti, Solowij, and Yücel 2016) - ⬇ grey matter volume in amygdala, prefrontal cortex, parietal cortex, and striatum (Battistella et al. 2014)	- ⬆activity of frontal and paralimbic regions, in addition to cerebellum (Chang and Chronicle 2007) - ⬇resting function of cerebellum and frontal regions (Iversen 2003)
Alcohol	⬇ attention and executive function (Thoma et al. 2011) ⬆emotional reactivity, distress tolerance recovered with abstinence (Winward et al. 2014) -⬇ verbal memory and visuospatial ability, and more post-drinking effects and drug use were associated with slower psychomotor speed [42] - ⬇ visuospatial performance for females with more past year drinking [43] - ⬇ sustained attention for males with more past year hangover symptoms [43]	-⬇left cingulate decreased cerebellar volumes and cerebellar activity during reward processing (Lisdahl et al. 2013; Cservenka Jones, and Nage 2015) -⬆ thickness of cortices in all four lobes (Jacobus et al. 2014) -⬇volume of left ventra diencephalon, left inferior and middle temporal gyrus, and left caudate and brain stem (Squeglia et al 2014) - ⬇ grey matter volume in lateral frontal and temporal regions ⬇ rates of white matter growth in corpus callosum and pons [40]		- differences in response in bilateral caudate, orbitofrontal cortex, medial frontal cortex/anterior cingulate and left insula (Dager et al. 2014) - changes in response for spatial working memory tasks despite adequate performance (Tapert et al. 2004) - ⬆response in bilateral parietal cortices and diminished response in other regions (left precentral gyrus, bilateral cerebellum) (Tapert et al. 2004) - ⬆BOLD activation in the bilateral striatum/globus pallidus, left anterior cingulate, bilateral cerebellum, and parahippocampal gyrus extending to the thalamus/substantia nigra; increased BOLD activation in response to alcohol cues in left anterior cingulate cortex and in right cerebellar region, though activation reduced to non-significance following abstinence [41]