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Cognitive outcomes in the ageing cannabis user

Dr Adrienne Withall, Prof Brian Draper
Research Centre DCRC Assessment and Better Care
Partner Institution
Project Description

Cannabis use is on the rise among older Australians, with national data indicating that between the years 1995 and 2013, the proportion of people aged 50–59 using cannabis in the past year rose from 1.5% to 7.3%. This increase is thought to be due to persistent use in the ageing ‘baby boomer’ generation, as well as increasing use for medicinal purposes.

Whilst there is accumulating evidence that heavy cannabis use in youth can be associated with lasting cognitive impairment (such as upon memory and attention), the majority of this research is on young adults. In contrast, little is known regarding the effects of cannabis on older individuals. Interestingly, it is also possible that cannabis has neuroprotective effects.

Recent preclinical findings suggest that cannabinoids can delay neurodegeneration, and there is increasing interest in cannabinoid medicines as possible treatments for various neurodegenerative disorders, including Alzheimer’s disease.

A better understanding of the effects of cannabis use upon cognitive outcomes in older adults is required to better inform consumers and health providers regarding the safety of cannabis in this group.

Therefore, the primary objectives of our project are to:

  1. Determine the cognitive performance of regular cannabis users aged ≥50 years compared to a matched control group of non-cannabis users, and
  2. To identify whether lifetime or current patterns of cannabis use are associated with impaired cognition in this age group.

Secondary objectives of the study are to:

  1. Examine whether patterns of cannabis use (including motivation for use – recreational or medicinal) are associated with physical and mental health, quality of life and psychosocial outcomes.
  2. To determine a validated cut-off point for the Montreal Cognitive Assessment (MoCA) as a cognitive screening tool for older, cannabis-using populations.

This case-control study will examine the effects of cannabis use upon cognition in a convenience sample (n=70) of regular cannabis users aged ≥50 yrs, compared to a matched control group with no history of regular cannabis use (n=30). Participants will undergo a cognitive screening test (the Montreal Cognitive Assessment) as well as comprehensive neuropsychological assessment. Additional measures of interest will include:

  • Recent and lifetime patterns of cannabis use and motivations for use
  • Other risk factors for cognitive impairment, including cerebrovascular disease, traumatic brain injury, mental health, other substance use, and family medical history
  • General health, quality of life and psychosocial functioning

The results of this study will better our understanding of the impact of cannabis associated cognitive impairment upon the health system. Specifically, such data will provide clinical advice to consumers and health providers regarding the effect of cannabis use in older populations – particularly relevant given increasing illicit and medical cannabis use in Australia in this group. In addition, the results of this study will help to inform future trials examining cannabinoid medications in the treatment of mild cognitive impairment and dementia. Lastly, the development of validated ‘cut-offs’ for cognitive screening instruments will enable to use of these tools in both clinical practice and in future trials of cannabinoid medications for various indications (e.g. chronic pain) in older populations.


Successful DCRC grant recipient 2016

 
Other team members:
 
Prof Nicholas Lintzeris, University of Sydney/South Eastern Sydney Local Area Health District
Dr Lauren Monds, University of Sydney/South Eastern Sydney Local Area Health District
Dr Nicole Ridley, South Eastern Sydney Local Area Health District
A/Prof Raimondo Bruno, University of Tasmania
A/Prof David Allsop, University of Sydney
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