Since legalisation in the USA, Canada and most recently in some European countries, there has been an interesting shift in the demographic of cannabis users. Recent epidemiological research indicates that older adults are reporting cannabis use in increasing numbers. ^{Reference Fernandez, Coughlin and Solway1,Reference Kuhns, Kroon, Colyer-Patel and Cousijn2} Despite this increase, much of the research directed at the implications of cannabis use is directed at a younger demographic. The research reported here by Yao et al. ^{Reference Yao, Maxwell and Ismail3} is timely in that it addresses the potential benefits and risks attached to older adults using cannabis either for recreational or medical purposes in treatment in a memory clinic for cognitive decline.

Whilst the authors note that there is a need for further investigations into the motivations for using cannabis in this demographic, they report that their sample was equally split between recreational and medical cannabis users. They also note that there was a significant relationship between cannabis use and a diagnosis of a mood disorder compared to non-users. This is a much-debated topic in the cannabis literature. Cannabis use for either self-medication or through a medical cannabis model for mood disorders is widely reported as a motivation for use. ^{Reference Turna, Patterson and Van Ameringen4} Although there is an extensive literature on the relationship between mood disorders and cannabis, the exact nature of that relationship is not clear. Research suggests that there is a bidirectional relationship between cannabis and mood, indicating that people who use cannabis do so because they have a negative mood, while cannabis itself may also be a cause of low mood. ^{Reference Feingold, Weinstein, Murillo-Rodriguez, Pandi-Perumal and Monti5}

The potential for negative consequences of the effects of cannabis on the brain and behaviour has implications for patients in treatment for neurological disorders who choose to use cannabis. As implied by Yao et al. ^{Reference Yao, Maxwell and Ismail3} patients in treatment for disorders related to cognitive decline may be seeking to treat both the primary cause of their decline and the comorbid symptoms associated with their diagnosis. This makes patients undergoing treatment for ageing-related diseases and disorders vulnerable to the consequences of using cannabis for either medical, self-medicating or recreational use. The data presented by Yao et al. ^{Reference Yao, Maxwell and Ismail3} provide an important insight into the incidence of cannabis use in relation to a population in treatment for cognitive decline. Future research targeting older adults in clinical populations is essential to better understand the potential positive and negative effects of cannabis use.