Student thesis: Doctoral Thesis


The purpose of this thesis was to assess whether heavy social drinking cannabis and smoking polydrug use results in more significant working memory task impairment when compared to heavy social drinkers. Analysis of the academic literature indicated that both binge drinking and cannabis consumption acts as a depressant on the central nervous system. Resulting in impaired Neurotransmission and disruption to Long Term Potentiation, the process through which memories are formed and maintained. Both binge drinking and cannabis consumption result in structural alterations to the brain, specifically the prefrontal cortex and dorsolateral prefrontal cortex, which is associated with impairments to working memory and attendant executive functions.

The study began with a scoping search in the; The PsycInfo, Pubmed, cinall and Web of Science databases in which either 'binge drinking', cannabis, and the polydrug was paired, working memory, memory, executive functions, and the corresponding synonyms. Results identified nine papers on visuospatial working memory and nine on verbal working memory that were suitable for analysis. No statically significant effect for visuospatial working memory reported. However, there was a large and statistically significant mean weighted effect size showing lower task performance by the polydrug users for verbal working memory

A 3-participant group design with a control group consisting of (N= 28) non-binging alcohol users (CO) and two experimental groups of (N=20) binge drinkers (HSD) and (N=22) binge drinking-cannabis smoking polydrug users (HSDCC). The study recruited participants via opportunity sampling from Edge Hill University. Participants completed a battery of assessments, including a background and drugs history questionnaire. The study also employed a series of computerised working-memory and Executive Functions tests. The study measured the Haematological response via fNIRS. Results found significant between groups effects for IC, IR, VSWM and ESS (2 and 3 Back conditions) With the HSDCC group reporting quicker reaction times for IC. The study found no other significant between groups effects. Results reported no between-groups effects for fNIRS through a multivariate impact on the left hemisphere for the N-Back. The study did report a significant negative correlation between the use of cannabis and Oxy-Hb changes in the left inferior PFC related to task performance on the COWAT was reported.
Date of Award17 Dec 2020
Original languageEnglish
Awarding Institution
  • Edge Hill University
SupervisorPHILIP MURPHY (Director of Studies), Cathy Montgomery (Supervisor) & Joanne Powell (Supervisor)

Cite this