Explain how alcohol and marijuana use affect the developing brain.

Question

What will be an ideal response?

Answer 1

Alcohol use is associated with changes in the structure and function of the adolescent brain. Compared with those who do not use alcohol, adolescents who drink alcohol moderately, show smaller brain volumes and grey matter density in areas responsible for executive control, including parts of the temporal and parietal lobes, and especially, the frontal cortex. Executive control is responsible for higher level cognitive functions such as planning, directing attention, and decision making. It also controls response inhibition, the ability to resist temptation, such as the rewards that come with risky but exciting activities, including drinking.
There is a strong dose-response relationship: Greater consumption of alcohol predicts decreased brain volume and less white matter integrity. The effects of adolescent alcohol use on brain function may be long lasting because alcohol use is associated with impaired neurogenesis and long term reductions in synaptic connections and memory in animals. Yet there is room for optimism because some research has shown that the adolescent brain can increase in volume and show improved executive function when alcohol use is discontinued. The extent and limits of this rebound effect are unclear.
Whereas regular alcohol use is associated predominantly with deficits in attention and executive function, regular marijuana use is associated with a broad set of neurocognitive deficits in attention, learning and memory, processing speed, visuospatial functioning, and executive control. Like alcohol use, regular marijuana use is associated with brain alterations, including reduced brain and grey matter volumes in the frontal lobe, followed by the parietal, and temporal lobes. Early onset of marijuana use, before age 18 and especially prior to age 16, is associated with more severe neurocognitive consequences, especially learning, memory, and executive function. One study suggests that cognitive function improved after 3 weeks of abstention, but attention deficits remained. It is unknown whether abstinence over a long period is associated with a rebound in function. Other research suggests that attention, verbal and working memory, and processing speed remain impaired up to 2 months later. Given the plasticity of the brain, some recovery of neurological function after abstention is expected, but the degree of recovery it not clear.