Familial analysis of MMN in cannabis users: A case study
Felicity
Webster1*,
Samantha
Broyd1,
Rodney
Croft1,
Erika
Van Hell1,
Lisa-marie
Greenwood1,
Stuart
Johnstone1,
Juanita
Todd2, 3,
Pat
Michie2, 3 and
Nadia
Solowij1, 3
-
1
University of Wollongong, School of Psychology and Centre for Psychophysics, Psychophysiology and Psychopharmacology, Australia
-
2
School of Psychology and Priority Research Centre for Translational Neuroscience and Mental Health, Australia
-
3
Schizophrenia Research Institute, Australia
Aims: The Mismatch Negativity (MMN) is a brain event-related potential marker of sensory memory and prediction error, and is thought to index N-methyl-D-aspartate receptor-mediated glutamate neurotransmission functionality. MMN is reduced in patients with schizophrenia and in their unaffected first degree relatives. MMN is also reduced in chronic cannabis users and in ex-cannabis users (33-month abstinent). Reduced MMN in ex-users suggests that cannabis-related deficits may persist after cessation of use, or alternatively this may reflect a pre-existing condition. One way of potentially elucidating this issue, is to conduct a familial analysis of the MMN in cannabis users and their non-user first degree relatives: attenuated MMN in relatives might indicate a familial vulnerability to cannabis use or to glutamatergic dysfunction. Method: One sibling pair (one cannabis user, one non-user sibling) and three non-user, unrelated, matched controls completed a multi-feature MMN paradigm with duration (100ms), frequency (1200Hz) and intensity (90dB) deviants (deviants 6%; standards 82%, 50ms, 1000Hz, 80dB). Results: Visual inspection of MMN waveforms and patterns of means suggests that non-user siblings have MMN amplitudes intermediate to their user-siblings (whose MMN is most attenuated) and controls. Examination of confidence intervals for controls (reflecting MMN amplitude variability across conditions) indicated that the user-sibling had smaller MMN amplitudes for all deviant conditions, and the non-user sibling had reduced duration MMN amplitude, compared to controls. Conclusions: These preliminary data provide early evidence that MMN might reflect a pre-existing vulnerability that is antecedent to cannabis use, but exacerbated by subsequent cannabis use, and may inform current conceptualisations of cannabis as a component cause of schizophrenia. However future research should attempt to replicate these findings in a larger sample.
Keywords:
mismatch negativity,
sibling,
Cannabis,
familial,
Glutamate
Conference:
ASP2013 - 23rd Annual meeting of the Australasian Society for Psychophysiology, Wollongong, Australia, 20 Nov - 22 Nov, 2013.
Presentation Type:
Poster Presentation
Topic:
Other...
Citation:
Webster
F,
Broyd
S,
Croft
R,
Van Hell
E,
Greenwood
L,
Johnstone
S,
Todd
J,
Michie
P and
Solowij
N
(2013). Familial analysis of MMN in cannabis users: A case study.
Conference Abstract:
ASP2013 - 23rd Annual meeting of the Australasian Society for Psychophysiology.
doi: 10.3389/conf.fnhum.2013.213.00022
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Received:
25 Oct 2013;
Published Online:
05 Nov 2013.
*
Correspondence:
Ms. Felicity Webster, University of Wollongong, School of Psychology and Centre for Psychophysics, Psychophysiology and Psychopharmacology, Wollongong, NSW, Australia, faw122@uowmail.edu.au