Marijuana trajectories and associations with driving risk behaviors in Canadian youth

Objective: Research on risky driving practices involving marijuana use among youth and young adults often relies on cross-sectional data, which fail to account for longitudinal changes in substance use patterns. A better understanding of the longitudinal patterns of marijuana use and its effect on risky driving practices during young adulthood is needed in order to better inform prevention efforts. The current study examined whether different longitudinal patterns of marijuana use across the transition from adolescence to young adulthood are associated with impaired driving risks in young adulthood.

Methods: Data were from the longitudinal Victoria Healthy Youth Survey, which interviewed youth biennially on 6 occasions across 10 years (2003 to 2013).

Results: Youth who reported consistently high levels of marijuana use from adolescence to young adulthood (chronic users) and youth who reported increasing levels of use across this period (increasers) were more likely to engage in risky impaired driving behaviors compared to the other 3 user groups (occasional users, decreasers, and abstainers). Frequency of marijuana use was also predictive of impaired driving risks in young adulthood after controlling for individual characteristics (age, sex, socioeconomic status, age of onset of marijuana use), frequency of other substance use (heavy episodic drinking and illicit drug use), and simultaneous use of marijuana and other substances (alcohol and illicit drugs). By young adulthood, youth who use marijuana more than once a week are more likely to simultaneously use alcohol and engage in heavy episodic drinking. They are also more likely take driving risks.

Conclusions: Harm reduction strategies and legislative approaches targeting impaired driving risks associated with marijuana use should include approaches to target these high-risk groups and to reduce simultaneous use of alcohol.     

Foraging bumblebees do not rate social information above personal experience

Foraging animals can acquire new information about food sources either individually or socially, but they can also opt to rely on information that they have already acquired, termed “personal information”. Although social information can provide an adaptive shortcut to new resources, recent theory predicts that investing too much time in acquiring new information can be detrimental. Here, we investigate whether foraging bumblebees (Bombus terrestris) strategically prioritize personal information unless there is evidence of environmental change. All bees in our study had personal information that one species of artificial flower was rewarding, and bees in the scent group then experienced social information about an alternative-scented species inside the nest, while a control group did not. On their next foraging bout, bees in both groups overwhelmingly used personal information when deciding where to forage. When bees subsequently learnt that the rewards offered by their preferred species had dwindled, bees that had social information were no quicker to abandon their personal information than control bees, but once they had sampled the alternative flowers, they showed greater commitment to that species than control bees. Thus, we found no evidence that social information is particularly important when personal information fails to produce rewards (a “copy when established behaviour is unproductive” strategy). Instead, bees used social information specifically to complement personal information.     

The dynamics of social learning in an insect model,the bumblebee (<Emphasis Type="Italic">Bombus terrestris</Emphasis>)

Bumblebees (Bombus terrestris) are attracted to those particular inflorescences where other bees are already foraging, a process known as local enhancement. Here, we use a quantitative analysis of learning in a foraging task to illustrate that this attraction can lead bees to learn more quickly which flower species are rewarding if they forage in the company of experienced conspecifics. This effect can also be elicited by model bees, rather than live demonstrators. We also show that local enhancement in bumblebees most likely reflects a general attraction to conspecifics that is not limited to a foraging context. Based on the widespread occurrence of both local enhancement and associative learning in the invertebrates, we suggest that social influences on learning in this group may be more common than the current literature would suggest and that invertebrates may provide a useful model for understanding how learning processes based on social information evolve.