Cannabis Effects on Brain Morphology in Aging
Condition: Study Focuses on Brain Morphology and Cognition in Older Subjects
MeSH terms: Marijuana Abuse
Study type: Observational

Summary: 
      Marijuana (Cannabis sativa) is the most widely used illicit drug worldwide, with 17.4 million
      Americans reporting past month use in 2010 and 4.6 million meeting criteria for dependence,
      underscoring the public health importance of understanding the biological implications of
      use. How heavy cannabis use affects brain structure and cognitive performance in late life is
      unknown. The ongoing maturation in the adolescent brain, including the developmental
      circuitry underlying memory performance and executive control puts the adolescent brain at
      high risk for detrimental effects of heavy cannabis use. With the aging of the 'baby boomer'
      generation, many people who used cannabis heavily as adolescents are now entering their
      senior years when age-related cognitive decline may begin. Cannabis use doubled in less than
      a decade during the 1970's when 38% of those surveyed in the U.S. Survey on Drug Abuse
      reported using cannabis and 12% of those users reported using cannabis more than 20 times a
      month. Understanding how heavy, early cannabis use may affect neurobiological and cognitive
      outcomes is of high importance for this aging population, which is already at risk for memory
      and cognitive deficits in aging. Because cannabis use appears to have a primary effect within
      the hippocampus, the main structure for memory and the structure affected most by age-related
      memory impairments and pre-clinical Alzheimer's disease, we expect that the effects of
      chronic cannabis use may be greatest during aging. To our knowledge, no study has
      investigated the long-term effects of adolescent cannabis use on hippocampal morphology and
      cognitive performance in an aging population.

      Investigators will investigate hippocampal integrity and cognitive performance using
      high-resolution magnetic resonance imaging (MRI), diffusion tensor imaging (DTI) and
      neuropsychological testing in an aging population of subjects (55-70 years old) who used
      cannabis more than 20 times a month for at least a year during adolescence. Investigators
      will compare data collected from heavy cannabis users to subjects who did not use cannabis
      but are matched for age, gender, education, light tobacco and light alcohol use. Finally,
      because family history and genetic risk are known to accelerate hippocampal morphology and
      memory decline in aging, the investigators will investigate whether possession of the APOE ε4
      variant in heavy cannabis users is synergistically related to thinner hippocampal cortex and
      white matter deficits.
    


Observational model: Case-Control
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        Subjects will be a community sample within the Los Angeles area. They will be recruited
        from the greater Los Angeles area using flyer postings in various areas of Los Angeles.
        Also, flyers will be posted in the Alzheimer's Disease Research Center at UCLA and the
        Longevity Center at UCLA as well as across the UCLA campus.
      
Keywords: Magnetic resonance imaging; Diffusion tensor imaging; Hippocampus; Cannabis; Geriatrics; Neuropsychology; Apolipoprotein E