Project
Determining The Cognitive Sequelae Of Adolescent Cannabis Use: A Longitudinal Cohort Study
The complicated relationship between patterns of cannabis use, cognition and personality is well recognised but poorly understood. Studies of adult heavy and long-term cannabis users consistently show deficits in memory, attention and executive functions that vary as a function of frequency, duration and age of onset of cannabis use. However, the extent to which these cognitive deficits are pre-existing is still unclear. It may be that individuals with premorbid cognitive deficits and certain personality characteristics tend to be more vulnerable to problematic patterns of cannabis use and greater adverse sequelae.
Evidence that the age of onset of cannabis use has been decreasing over recent decades is particularly concerning, as there is a growing literature to suggest that early onset use is associated with greater adverse consequences. Moreover, with adolescence representing a significant period of neural development and maturation of cognitive abilities, any compromise to these functions may substantially impair developmental outcomes, and further exacerbate cannabis-related sequelae. Conversely, preserved cognitive abilities and certain personality characteristics may act to buffer individuals from developing problematic patterns of cannabis use and related sequelae. For example, high executive ability combined with high constraint and low negative affect may protect against problematic use.
These complex relationships between cognition, patterns of cannabis use and personality characteristics have not been explored from a contemporary neurodevelopmental perspective. The current project offers a unique opportunity to examine these important relationships by following up a sample of 750 adolescents (the Wollongong Youth Study [WYS]) that we have comprehensively assessed annually since 2003 on measures of personality and academic ability. The broad aim of the proposed study is to dissociate pre-existing cognitive and personality factors from the neuropsychological sequelae of adolescent cannabis use, building upon our existing dataset from this unique cohort. Based on current data available from the sample and further comprehensive assessment of substance use this year, we will identify a group of cannabis users (n≈80) with a range of patterns of exposure to cannabis. In 2008, we propose to further assess this cannabis-using adolescent group by means of a battery of specific experimental cognitive and neuropsychological tests and compare their performance to matched groups of non-substance-using adolescents and alcohol-using adolescents without cannabis use from the same cohort.
The findings will shed light on the complicated relationship between personality, cannabis use and cognition during a key developmental period. In turn, this will enable identification of individuals at “high-risk” for cannabis use as well as associated cognitive sequelae, informing both prevention and early intervention strategies for youth.
Investigators
CIs – Dr Nadia Solowij, Assoc Prof Murat Yücel, Assoc Prof Dan Lubman, Dr Joseph Ciarrochi, Assoc Prof Patrick Heaven
The Effect Of THC On Cognition, Driving Performance, Fatigue And Drug Detection Systems
The current project has three main research questions
- To examine the effect of THC on driving performance during the acute and residual phases of cannabis consumption, along with measures of fatigue and vigilance.
- To examine the performance (accuracy and effectiveness) of a potential Roadside Drug Detection Device, The Cognitive Drug Research Device (CDRD) in detecting driving impairment due to recent cannabis use. The study will also compare the performance on the CDRC to the PIT to determine which method is more effective in detecting impairment.
- To examine the sensitivity of several new or updated saliva and sweat drug screening devices to test for the presence of THC.
Investigators
CIs - Prof Con Stough, Ms Rebecca King, Prof Andrew Scholey, Dr Edward Ogden, Dr Michael Keane, Assoc Prof Murat Yücel
Quantifying the neurocognitive and neurobiological impact of cannabis across the life span: the evolution of memory and executive control deficits
Cannabis is the most widely abused illicit drug and its early use by adolescents has been associated with a wide range of adverse outcomes, including cognitive impairments, poor socio-occupational functioning and mental health problems. Recent research has identified impairments in memory, attention and executive functions in adult chronic users in the unintoxicated state. These deficits have variously been attributed to dose, frequency or duration of cannabis use and further research is necessary to elucidate the parameters of use that lead to clinically significant dysfunction. In addition, evidence that the age of onset of cannabis use has been decreasing over recent decades is particularly concerning, as there is a growing literature to suggest that early onset use is associated with greater adverse consequences. Through collaborations with Dr Nadia Solowij, we are now investigating the effects of frequency and duration of cannabis use on verbal learning and visuospatial memory in cohorts of adult and adolescent cannabis users utilising sophisticated brain imaging techniques.
Investigators
Dr Nadia Solowij, Dr Marc Seal, Assoc Prof Dan Lubman, Assoc Prof Murat Yücel, Prof Philip McGuire, Dr Alex Fornito, Dr Ben Harrison, Prof Christos Pantelis
Students
Valentina Lorenzetti, Ian Harding, Claudia Marck
Research Assistants
Michael Takagi, Karissa Searle
Ethics
Melbourne Health: MHREC