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The Effects of Cannabis Use on Cognitive Functioning in Adolescents and Young Adults


Type

Thesis

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Authors

Selamoglu, Ayla 

Abstract

Abstract

Effects of Cannabis Use on Cognitive Functioning in Adolescents and Young Adults Ayla Selamoglu

Cannabis use amongst adolescents and young adults is becoming ubiquitous. Access to cannabis is at a steady increase with rates of use now exceeding cigarettes and drawing nearer towards rates of alcohol use. With rapidly changing laws worldwide legalising the use of cannabis for medical or recreational purposes, there has been an overall decrease in the perceived harm of cannabis use. However, scientific evidence suggests that the developing brain is most vulnerable during the period of adolescence and young adulthood where it undergoes profound dynamic structural, neurochemical, and white matter changes. As such, this period may be a unique window during which cannabis exerts its heaviest impact on neurocognitive functioning. This has become a major public health concern, as cannabis use among adolescents and young adults is likely to increase with further legalisation and subsequent increased availability. The studies in this thesis aims to assess the domains and severity of cognitive impairments associated with cannabis dependency use in a population of adolescents and young adults, and explore the potential use of an existing pharmacological agent to treat cognitive impairments. While these studies cover a wide range of cognitive domains, the tests administered are predominantly non-verbal. Chapter 1 provides a review of adolescent neurodevelopment which continues into young adulthood until approximately the age of 25. It discusses the psychopharmacology of cannabis from a biological basis, its pharmacokinetics, and the primary endocannabinoid receptors. The levels of potency for varying types of cannabis, as well as the acute, residual and persistent effects of use are reviewed. Cognition, intelligence quotient (IQ), gender differences, socioeconomic status (SES), cognitive rehabilitation, and prevention and intervention methods are also discussed. Chapter 2 explains cannabis use in the context of neuroethics by analysing the issues surrounding use in adolescents, the legalisation debate for recreational and medical use, its impact on neurodevelopment and functioning, academic attainment, as well as psychiatric conditions and general wellbeing. It further assesses the motivations for cannabis use, SES, and the global burden of disease (GBD). Chapter 3 tests cognitive impairments in young adults with Cannabis Use Disorder (CUD) compared to controls by implementing reliable measures from the Cambridge Neuropsychological Test Automated Battery (CANTAB). Cannabis use and dependency during young adulthood revealed cognitive impairments in risky behaviour and memory. Chapter 4 evaluates a novel treatment for CUD by exploring the effects of the drug gabapentin vs. placebo for reducing cannabis related impairments in executive and daily functioning. Cognitive functioning was assessed with CANTAB and found no noticeable differences between gabapentin vs. placebo in cannabis related executive functioning and learning and memory. In the Discussion section, it was concluded that cannabis dependency is associated with cognitive impairments. There was no effect of gabapentin treatment and therefore, there is a need for effective treatments to be developed for cannabis dependency. Future studies with longitudinal design will help to clarify whether these cognitive impairments are pre-existing or follow a diagnosis of cannabis dependency. Prospective studies could also clarify whether people with cannabis dependency are particularly vulnerable to cognitive impairments when cannabis use begins in adolescence or young adulthood.

Description

Date

2019-12-01

Advisors

Sahakian, Barbara

Keywords

cannabis, cognition, neuropsychology, psychiatry, psychoactive, adolescents, young adults, CBD, THC, gabapentin, neuroethics, CANTAB

Qualification

Doctor of Philosophy (PhD)

Awarding Institution

University of Cambridge
Sponsorship
Department of Psychiatry