A new study suggests people with mental illness are more than seven times as likely to use marijuana weekly than people without a mental illness.

In total, 4.4 percent of individuals with a mental illness in the past 12 months reported using cannabis weekly, compared to 0.6 percent among individuals without any mental illness.

Cannabis use disorders occurred among 4 percent of those with mental illness versus 0.4 per cent among those without.

Researchers also noted that, although cannabis use is generally higher among younger people, the association between mental illness and cannabis use was pervasive across most age groups.