Dr Daniel Hale

Project Title: Cannabis use – long-term mental health outcomes and predictors of harm

While cannabis use has been linked with a range of mental health issues, including depression, anxiety and cognitive impairments, it is difficult to examine the causal contribution of cannabis to these issues. The associations may stem partly or wholly from differences between cannabis-users and non-users.

Our research uses British longitudinal studies which follow participants over many decades. This allows us to account for pre-existing differences in regards to mental health and other key factors, and examine patterns of cannabis use throughout the life course. Much previous research has been criticized for not accounting for such factors. This richer data will allow for stronger causal inferences. It will also allow us to examine older age groups, for whom there has been little investigation regarding cannabis and mental health. Our emerging findings suggest that having ever used cannabis or using it within the past year is unassociated with early cognitive decline in people within their mid-50s. This is in contrast to the results of past studies, though our research takes account of more pre-existing psychological and behavioural factors and focuses on an under-studied age group.