There is further evidence that smoking cannabis during pregnancy can have lifelong consequences for offspring.
In a new study, Western University researchers examined the effects prenatal cannabis exposure can have on brain development. What they found was that it led to lasting, substantial cognitive and memory function problems.
Researchers used rats, not humans, for the study. They injected pregnant rats daily with mild to moderate amounts of THC. Once born, the THC exposed rats were tracked through adulthood. Scientists measured the effects of prenatal THC, the primary psychoactive component in cannabis, on the rodents through social interaction, spontaneous alternation, and object recognition tests.
“Over the past two decades, concentrations of THC have risen from three per cent to 22 per cent. THC can pass through the placenta and impact the developing fetal brain,” said Mohammed H. Sarikahya, study co-author and member of the Addictions Research Group at Western’s Schulich school of medicine and dentistry. “Our research shows that prenatal THC exposure can lead to serious cognitive and memory deficits that are sex-dependent, enduring and potentially lifelong.”
Among the adverse effects were changes to the offspring’s desire to socialize, memory of previous social encounters, and learning capabilities. These changes were found in both males and females, researchers said. Females showed very active brain activity in the part of the brain involved with emotion and memory called the ventral hippocampus. Males had less activity in that same part of the brain.
“This suggests prenatal cannabis exposure can have sex-specific effects on the developing brain, leading to different patterns of cognitive and behavioural disturbances in males and females,” said Steven Laviolette, study co-author and professor at Western’s Schulich school of medicine and dentistry.
Through their work, researchers believe they may have found a potential way to reduce the adverse effects of prenatal THC exposure by targeting irregularities in brain fatty acids.
The study comes at a time when the Canadian Centre on Substance Use and Addiction reports cannabis usage has risen up to 22 per cent among Canadian pregnant women aged 18-24.
The study has been published in the journal Molecular Psychiatry.
