Keep off the grass? Cannabis, cognition and addiction

Abstract

In an increasing number of states and countries, cannabis now stands poised to join alcohol and tobacco as a legal drug. Quantifying the relative adverse and beneficial effects of cannabis and its constituent cannabinoids should therefore be prioritized. Whereas newspaper headlines have focused on links between cannabis and psychosis, less attention has been paid to the much more common problem of cannabis addiction. Certain cognitive changes have also been attributed to cannabis use, although their causality and longevity are fiercely debated. Identifying why some individuals are more vulnerable than others to the adverse effects of cannabis is now of paramount importance to public health. Here, we review the current state of knowledge about such vulnerability factors, the variations in types of cannabis, and the relationship between these and cognition and addiction.

Individual and combined effects of acute delta-9-tetrahydrocannabinol and cannabidiol on psychotomimetic symptoms and memory function

“…Possible consequences of use include dependency, cognitive impairment and increased risk of psychotic illness 2 . However, most people who try cannabis do not experience prolonged adverse effects.…”

Can we make cannabis safer?

“…The main possible adverse effects associated with cannabis use are dependence, cognitive and educational impairment and psychosis 22 . Crucially, evidence suggests that the incidence of adverse consequences of cannabis use is associated with the amount of THC and CBD it contains.…”

“…There has been considerable debate regarding whether the use of cannabis may have lasting negative effects on memory functioning, intelligence and other aspects of cognition in the normal population 22 . A recent study across three large samples found that cannabis use before the age of 17 was related to lower rates of high-school completion and degree attainment 50 .…”

Early cannabis use and its relation to the development of psychiatric disorders: a review

“…Studying the child-youth population is important because early onset of use (before age 15), associated with chronic use in young people increases cognitive impairment in executive and neurocognitive functions (Curran et al, 2016;Fontes et al, 2011), and may be associated with the development of dependency in adulthood (Gonzalvo, Barral, Grau-López, Esteve, & Roncero, 2011). This high use may be partly due to the fact that people tend to consider this drug as one of the least harmful in the short and long term, compared with other substances.…”