The effects of a month's abstinence from cannabis on young people

L’cannabis use among teenagers is often associated with the idea poor school performance and’reduced cognitive capacity. At this age, the brain is still developing, and cannabis consumption could cause irreversible damage on adolescent development. With these considerations in mind, a team of researchers developed the a study to determine the effects of cannabis abstinence on cognition.

The study

The researchers involved 88 teenagers and young adults, aged 16 to 25, who smoked cannabis at least once a week. Some of them were asked to respect an abstinence period of four weeks.

Abstinence was remunerated by money and verified by urine tests. In total, 88.7% of the participants required to abstain succeeded in doing so. To ensure correct results, the researchers controlled for individual factors such as learning ability, mood, cognition and motivation, as well as the frequency and intensity of personal consumption.

Attention and memory tests were then carried out on the participants each week. An improvement in memory capacity, particularly verbal memory, was observed from the very first week in abstainers compared with smokers. The improvement was greatest in the first week, but continued in subsequent weeks. On the other hand, there was no difference in attention between the two groups. Randi Schuster, PhD student at Harvard's Center for Addiction Medicine and lead author of the study sums up: «Our findings provide two compelling pieces of evidence. The first is that adolescents learn better when they don't use cannabis. The second - which is the good news - is that deficits associated with cannabis use are not permanent and improve fairly quickly after stopping consumption».

She concludes that «the ability to learn or register new information, a critical aspect of success in school, improves with long-term abstinence from cannabis. Young users who stop using for a week or more are thus better equipped to learn effectively, and in fact are more likely to succeed academically. We can confidently say, based on what these results suggest, that abstinence helps young people learn, whereas continued cannabis use interferes with that learning».

Study limits and scope

Schuster adds, however, that many questions remain to be investigated, such as «does attention improve and memory continue to increase with longer periods of abstinence».

Another, larger study on cognition is planned soon, with even younger participants, aged 13 to 19, and a reference group of non-cannabis users. It will determine whether abstinence from cannabis leads to a return to levels of cognitive performance identical to those of non-users. The period of abstinence will be six months.

The results of this study provide an opportunity to implement intelligent, information-based prevention to help young people who still use cannabis to develop a more responsible consumption pattern. What's more, they show that, under the conditions of the study, cognitive impairment is not irreversible.

A previous study had denounced the fact that previous research tended to «exaggerate» the effects of consumption among young people.

A future 4-year study in California will attempt to answer the question of the long-term effects of cannabis on young people.