Poster(s)
The Effects of Cannabis, 'Ecstasy' (MDMA) and IQ on Visuopatial Memory Performance
P.N. murphy
Edge Hill University
P.G. Erwin
Edge Hill University
M. Wareing
Liverpool John Mores University
L. Blackman
Edge Hill University
K. Yanulevitch
Edge Hill University
E. Keane
Edge Hill University
J.E. Fisk
University of Central Lancashire
L. MacIver
Edge Hill University
T. O'Connor
Edge Hill University
C. Montgomery
Liverpool John Moores University
Background
This project investigated further the respective contributions of ecstasy (MDMA) and cannabis to aberrant visuospatial processing, with earlier studies having reported both drugs to be associated with deficits in such functioning.
Method
Passive visuospatial memory (PVM) was operationalised by recalling sequentially highlighted computer generated grid squares. Visuospatial working memory (VWM) was operationalised by a similar task requiring concurrent processing for a pointing task. The dependent variable for both tasks was the number of correct grid locations recalled in sequence. Participants (N = 47, 24 male) had a mean age of 22.0 years (SD = 3.6 years). All participants claimed to have been drug-free for at least 7 days. Measures of IQ and mood were also taken.
Results
Hierarchical regression analyses for both tasks employed IQ in the initial model, with measures of time since last cannabis use and estimated cannabis consumption added to the final model. For PVM the final model significantly improved prediction, with time since last use being significantly and inversely predictive of performance. IQ was not predictive in the final model. For VWM, IQ was significantly and positively predictive of performance in both models. Prediction was not significantly improved in the final model. However, time since last use approached significance, being inversely related to performance once again. Ecstasy related variables appeared to have no relationship to performance on either task.
Conclusions
Lower levels of ecstasy consumption, compared to previous studies, may account for the lack of any relationship to VWM performance here. The predictive ability of the cannabis related variables is consistent with earlier findings from our laboratories that cannabis may affect both PVM and VWM, whilst ecstasy may only affect executive based VWM processes. However, the inverse nature of performance prediction by time since last use requires further research.
