Acute glycine administration increases mismatch negativity in chronic schizophrenia
Lisa-marie
Greenwood1*,
Sumie
Leung1,
Patricia
Michie2, 3,
Amity
Green4,
Pradeep
Nathan5, 6,
Paul
Fitzgerald7,
Patrick
Johnston8,
Nadia
Solowij1, 9,
Jayashri
Kulkarni4 and
Rodney
Croft1
-
1
University of Wollongong, School of Psychology, Australia
-
2
University of Newcastle, School of Psychology and Priority Research Centre for Brain and Mental Health, Australia
-
3
Schizophrenia Research Institute, Australia
-
4
Monash University, Monash Alfred Psychiatry Research Centre, Australia
-
5
Monash University, School of Psychology and Psychiatry, Australia
-
6
University of Cambridge, Department of Psychiatry, United Kingdom
-
7
Monash University, Monash Alfred Psychiatry Research Centre, Australia
-
8
University of York, Department of Psychology and York Neuroimaging Centre, United Kingdom
-
9
Schizophrenia International Research Institute, Australia
NMDA receptor hypofunction, indexed by reduced mismatch negativity (MMN), is proposed to underlie deficits in early auditory processing in schizophrenia (SCZ). Glycine increases NMDA neurotransmission and has been reported to improve functioning as an adjunct to antipsychotic medication. The effects of glycine on MMN in SCZ are unknown and warrant further investigation.
Duration (100ms; Standards 50ms, 100Hz, 80dB) and frequency (1100Hz) MMN were compared, at baseline, between 23 participants with a primary diagnosis of SCZ or schizoaffective disorder and 21 matched controls. MMN was reassessed in the patient group after administration of either 0.2g/kg glycine or placebo. Patients were rated on the Positive and Negative Syndrome Scale (PANSS) at baseline and provided blood samples pre- and post-glycine administration to monitor glycine serum levels.
At baseline, duration MMN was reduced in SCZ compared to controls (p=.002), but frequency MMN was reduced at trend level only (p=.065). Smaller duration MMN at baseline was associated with greater PANSS negative symptoms (p=.023) in patients. The difference between pre- and post-treatment duration MMN was increased after glycine when compared to placebo (p=.009); that is, glycine increased MMN. No difference was observed for frequency MMN and correlations between MMN and glycine serum were not found.
These findings suggest that duration MMN is associated with negative symptoms and that acute (0.2g/kg) glycine increases duration MMN in SCZ. Our findings offer insight into the pathophysiology of reduced MMN in SCZ. MMN is a latent biomarker of NMDA function and further research should determine whether prolonged glycine treatment ameliorates reduced MMN in SCZ.
Keywords:
Glycine,
Schizophrenia,
NMDA,
MMN,
mismatch negativity
Conference:
XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014.
Presentation Type:
Poster
Topic:
Memory and Learning
Citation:
Greenwood
L,
Leung
S,
Michie
P,
Green
A,
Nathan
P,
Fitzgerald
P,
Johnston
P,
Solowij
N,
Kulkarni
J and
Croft
R
(2015). Acute glycine administration increases mismatch negativity in chronic schizophrenia.
Conference Abstract:
XII International Conference on Cognitive Neuroscience (ICON-XII).
doi: 10.3389/conf.fnhum.2015.217.00139
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Received:
19 Feb 2015;
Published Online:
24 Apr 2015.
*
Correspondence:
Ms. Lisa-marie Greenwood, University of Wollongong, School of Psychology, Wollongong, Australia, lgreenwo@uow.edu.au