Evidence of Brain Damage in Chronic Ketamine Users: a Brain Imaging Study
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Abstract


Background
and objectives:


The objectives of this study were to ascertain
the pattern of grey and white matter volume reduction and regional metabolic
and activation abnormalities in chronic ketamine
users, and to evaluate the correlations between these brain abnormalities and
cognitive impairments in chronic ketamine users in Hong Kong.


Design:


Cross-sectional
observational study.


Setting:


Counselling Centre
for Psychotropic Substance Abusers in Hong Kong.


Participants:


One hundred and
thirty-six participants were recruited from October 2011 to April 2014. The participants
were divided into two groups: ketamine users (79) and healthy controls (57).


Main
outcome measures:


Psychiatric assessments
included screening with self-rating questionnaires and face-to-face interviews.
All of the participants completed a detailed cognitive battery that covered
general intelligence, verbal and visual memory, executive functions, motor
speed and language. All of the participants underwent magnetic resonance imaging
of the brain.


Results:


Many of the participants
in the ketamine group also frequently used cocaine and cannabis. Among the
ketamine users, 12.6% were diagnosed with a mood disorder and 8.9% with an anxiety
disorder. The participants in the ketamine group had worse performance than the
healthy controls on tests of general intelligence, verbal, visual and working
memory and executive functioning.


In terms of grey
matter volumes, the right orbitofrontal cortex, right medial prefrontal cortex,
left and right hippocampus and possibly the left orbitofrontal cortex were
smaller in the ketamine group. In contrast, the volumes of the left basal
ganglia, left putamen and possibly the left caudate were higher in the ketamine
group. In terms of white matter volumes, the ketamine group had a lower
periventricular white matter volume in the right hemisphere. The grey matter
volumes of the left and right orbitofrontal cortex, right medial prefrontal
cortex, left basal ganglia and left putamen, and right periventricular white
matter volume were negatively correlated with the severity of ketamine
dependence. The hippocampal volumes were correlated with performance on the
arithmetic, information and digit span tests. The periventricular white matter volume
also correlated with the information score.


A functional
connectivity examination of the default mode network revealed significantly
decreased connectivity in the medial part of the bilateral superior frontal
gyrus, left middle frontal gyrus, bilateral gyrus rectus, left superior
temporal pole, left inferior temporal gyrus, bilateral angular gyrus and
bilateral cerebellum crus II in the ketamine group. This group also displayed
increased connectivity in the bilateral precuneus and right inferior occipital
gyrus.


Conclusions:


The results provide
imaging evidence of brain damage in chronic ketamine users. Chronic ketamine
use was associated with reduced grey and white matter volumes in certain
regions of the brain. Chronic ketamine use was also associated with altered
functional connectivity with the default mode network. Abnormal brain
structures and altered functional organisation of the brain network may
underlie the hypersensitivity towards drug related cues but weakened cognitive
control in those with ketamine addiction. Longitudinal or prospective studies would
help to strengthen the evidence on the reversibility of the structural and
functional brain damage caused by ketamine.

Acceptance Date03/10/2016
All Author(s) ListLin Y, Liang HJ, Liang Y, Lai WY
Name of Conference17th Pacific Rim College of Psychiatrists Scientific Meeting
Start Date of Conference03/11/2016
End Date of Conference05/11/2016
Place of ConferenceKaohsiung
Country/Region of ConferenceTaiwan
Year2016
LanguagesEnglish-United States

Last updated on 2018-21-01 at 21:38