Introduction Methods Results Conclusions

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Student: Miranda Heneghan Supervisor : Dr Kyle Dyer (KCL) & Dr James .... Montgomery C, Ashmore K V, Jansari A (2011) The effects of a modest dose of ...
Mediating effects of executive functioning on alcohol-induced prospective memory failure

Student: Miranda Heneghan Supervisor : Dr Kyle Dyer (KCL) & Dr James Smith-Spark (LSBU) Department of Neuroscience and Department of Addictions, Institute of Psychiatry, Kings College, University of London

Introduction

It is well established that alcohol affects both executive function and prospective memory (PM). However less is known about the mediating effects executive function (EF) may have on PM while under the influence of alcohol. This study investigated whether participants under the influence of alcohol display poorer performance on PM tasks compared to those in the placebo condition and whether EF mediates PM task performance when alcohol is consumed.

Methods Eighteen male participants completed a series of baseline executive functioning tests, focusing on “set-shifting”, “inhibition” and “updating” abilities. They then completed a task based measure of prospective memory (the MIST) twice-under the influence of alcohol (0.06g/kg BAC) and again in the placebo condition

On arrival

Paper based tasks*

• Consent form • Audit & Eligibility Questionnaires • PMRQ • Verbal Fluency tests • Plus/Minus Task • Go/No Go task • Opspan task

Computer tasks* • Placebo or • Alcohol

Alcohol Administration • Wait until BAC is 0.6g/kg in alcohol condition

Breathalyse • Administer Form A on Visit 1 • Administer Form B on Visit 2

MIST

End of session * Visit one only

• Instruct on delayed PM task • Inform participant which condition they were in • Sign release form *if consumed alcohol.

Results

A paired-samples t-test was conducted to compare total MIST scores in the placebo and alcohol conditions. There was a significant difference in the scores for the placebo condition (M=45.67, SD=3.18) and the alcohol condition (M=42.17, SD=5.29) conditions; t (17) = 3.58, p = .006. The MIST was carried out in the alcohol condition when participants reached a BAC of 0.06g/kg. These results suggest that a moderate does of alcohol does have an effect on prospective memory. Specifically, our results suggest that when the participants consume alcohol, they perform less well on the MIST. Further paired sample t-tests were then conducted to examine which domains within the MIST questionnaire were significantly different in the placebo and alcohol conditions. Table 1: Descriptive Statistics and t-test results for each domain of the MIST in the placebo and alcohol conditions n=18 95% CI for Placebo Alcohol Outcome n t df sig Mean M SD M SD Difference Two- minute delay

7.83

.51

7.5

.99

18

-0.18, 0.85

1.374

17

.187

Fifteen- minute delay

7.39

.78

6.56

1.42

18

0.24, 1.43

2.945

17

.009*

Time cue

7.44

.86

6.61

1.42

18

0.10, 1.56

2.413

17

.027*

7.78 7.61

.65 .85

7.44 7.05

.92 .99

18 18

-0.18, 0.85 0.01, 1.10

1.374 2.149

17 17

.187 .046*

7.61

.71

7

1.14

18

0.02, 1.21

2.170

17

.045*

Event cue Verbal response Action response

A series of linear regressions were conducted to determine if the difference between MIST scores in the placebo and Alcohol conditions could be predicted by performance in the various tests of executive function employed in this study- looking at total scores and the individual subscales.

Table 2: Summary of regression analyses, n=18 Independent variable Plus Minus Go/ No Go OpSpan Go/ No Go Go/ No Go OpSpan

Dependent variable MIST MIST MIST MIST MIST MIST

total score difference total score difference total score difference 15-minute delay difference Time-Cue difference Time-Cue difference

R square .112 .118 .036 .254 .254 .167

B .185 -.170 -.088 -.073 -.079 -.066

Std Error .130 .124 .113 .033 .036 .037

Beta value .335 -.343 -.191 -.504 -.504 -.409

T

Sig

1.423 -1.366 -.776 -2.183 -2.186 -1.791

.174 .194 .449 .047* .046* .092

Conclusions

This study demonstrated that the acute consumption of alcohol may cause impairments in prospective memory performance. It also suggests that certain constructs of executive functioning; especially inhibition and updating abilities may have a mediating effect on Time- based PM performance under the influence of alcohol. References Abernathy K, Chandler LJ, Woodward JJ (2010) Alcohol and the prefrontal cortex. Int Rev Neurobiol 91:289–320 Heffernan TM (2008) The impact of excessive alcohol use on prospective memory: a brief review. Curr Drug Abuse Rev 1:36–41 Montgomery C, Ashmore K V, Jansari A (2011) The effects of a modest dose of alcohol on executive functioning and prospective memory. :208–215.