Earlier this year, our laboratory published work demonstrating that rats whose mothers were given low-dose THC (or an analogous synthetic cannabinoid) while pregnant showed significant changes in synaptic plasticity and altered levels of several important proteins lasting well into adulthood. We found that the consequences of these changes manifested as a reduced sociability in the exposed offspring. Male rats in particular were much less likely to approach, play with, or sniff other rats.4
These findings parallel sociobehavioral changes seen in young adult humans exposed to cannabis during gestation. And scientists are now linking those effects to changes in the brain that are similar to what we observed in rats. Using functional MRI technology, for example, researchers participating in the Ottawa Prenatal Prospective Study observed a reduction in activity in the prefrontal cortices of adult offspring of mothers who smoked marijuana during pregnancy. This drop was associated with decreased working memory, echoing the attentional problems and memory dysfunction seen as early as infancy.5
Cannabis is also likely to affect the amygdala, which is critical for emotional development. In 2004, Yasmin Hurd of the Karolinska Institute and colleagues identified a significant reduction in dopamine D2 receptor mRNA in the amygdalae of fetal brains that correlated with the reported quantity of cannabis consumed by their mothers.6 (The fetuses were all between 18 and 22 weeks of gestation and donated by women who underwent voluntary abortions.) Given the known role of amygdala dopamine signaling in the regulation of mood and emotion, these findings could explain the increased depressive-like symptoms observed in children following cannabis exposure in utero, as well as these kids’ propensity towards inattention and impulsivity.
The problem of infant cannabis exposure extends well beyond pregnancy. THC and its lipophilic cannabinoid analogs are readily transferred through breast milk of humans and other mammals, and animal studies have pointed to these compounds’ influence on development throughout the pre-weaning period. Worse yet, given that these cannabinoids linger in the body for weeks, the “pump-and-dump” approach often employed to avoid feeding alcohol-laden milk to an infant isn’t as effective for cannabis users—a Friday night joint can continue to deliver active cannabinoids through breast milk throughout the weekend and into the next week.
Conflict-related neural activations. Between-group t-map of conflict-related activations (voxel-wise cluster-defining threshold of p
The development of neural circuits in youth, at a particularly important time in their lives, can be heavily influenced by external factors—specifically the frequent and regular use of cannabis. A new study in the Journal of the American Academy of Child and Adolescent Psychiatry (JAACAP) reports that alterations in cognitive control—an ensemble of processes by which the mind governs, regulates and guides behaviors, impulses, and decision-making based on goals are directly affected.
Cannabis-induced psychosis has reached crisis levels, forcing the NHS [National Health Service] to open the first clinic specifically treating addicts of the mind-altering drug, The Mail on Sunday can reveal.
The clinic has been launched by a leading psychiatrist who warns that psychosis among users of skunk – a very strong strain of cannabis flooding the streets – has become ‘a crisis that we can simply no longer ignore’, with tens of thousands of people affected.
Dr Di Forti, a consultant adult psychiatrist and lecturer at King’s College London, said she decided to launch the clinic after being overwhelmed by the number of psychosis patients with a history of cannabis use.
‘It became ridiculous how many psychosis patients were also cannabis smokers,’ she said.
‘It got to the point where two-thirds of my psychosis patients had a history of cannabis use.’
Talking about the former trainee teacher, Dr Di Forti said: ‘He has a degree and professional skills but because he’s stoned all day, he can’t even read a book at the moment. He was training to be a teacher before cannabis took over his life but right now his main goal is simply to be able to use his brain again.’
Calls for the legalisation of cannabis for recreational use have grown in the last year, helped by the Government permitting its limited use for medical treatment.
But Dr Di Forti warned against following the lead of Canada and the U.S. states of California and Colorado, where legalisation has seen usage increase.
‘My concern is that there is no way you can legalise recreational cannabis without cannabis use going up, as has happened in America, and there is a potential for a lot of people to come to harm,’ she said.
Treatment comprises a mix of anti-psychotic medication, sessions with therapists, and motivational meetings to wean patients off cannabis.
Dr Di Forti said: ‘The problem has been that while you’re trying to do all these things to help patients with their psychotic episodes, they are smoking from half-an-hour after they wake up until just before they go to bed, so they’re basically stoned all the time.
‘Trying to reintegrate them by getting them to join a local football team or do an art class is very difficult. Often they will be so stoned that they will have no motivation to address their psychosis. That is something we have to work through.’