There are usually two reasons people give when asked why they don’t enjoy cannabis: either it makes them feel too sleepy or too paranoid.

While it is known that the same strain can affect consumers in completely different ways, researchers are still trying to pinpoint why reactions vary from person to person.

It turns out that there might be an underlying genetic factor that contributes to the negative effects of cannabis, like paranoia and cannabis-induced psychosis. A study published on July 5 this year, from researchers at the University of Western Ontario has found a relationship between THC and nucleus accumbens in the brain responsible for reward behaviour and aversion processing.

If the THC is processed in the front area of the nucleus accumbens, then the user is likely to have a positive experience and feelings of euphoria. However, if the THC attaches to the receptors in the anterior of the nucleus accumbens, the user is likely to experience adverse symptoms such as paranoia.

The kicker is that whether the THC attaches to the frontal or anterior nucleus accumbens isn’t caused by mood or personality type, but rather a genetic predisposition.

For some, #cannabis causes a rewarding high. For others, it can cause psychiatric side effects. Researchers at @WesternUstudied THC's effect on a rat brain to show that how marijuana affects us may come down to the region of the brain it is acting on. https://t.co/Cp7yesQwRI

— Schulich WesternU (@SchulichMedDent) July 9, 2019

“These findings are important because they suggest why some people have a very positive experience with marijuana when others have a very negative experience,” said Christopher Norris, PhD candidate at Western University, in a statement about the research. “Because the reward and aversion are produced by anatomically distinct areas, the different effects between individuals is likely due to genetic variation leading to differential sensitivity of each area.”

The preliminary findings will open the door to further research and discovery in the factors that contribute to paranoia, and possibly even cannabis-induced psychosis, in cannabis consumers.