Neuroimaging Findings in Methamphetamine Abusers

Abstract

Methamphetamine (MA) is a drug which has got a considerable prevalence of abuse in the world. Therefore, it is of great importance to understand the deficits and problems that it makes in brain, structurally and functionally, in order to increase knowledge of people about it and help finding better ways of treatments. Neuroimaging techniques as the most powerful tools to study the brain functions and structures, in the recent decades have been used to find out the brain deficits caused by the MA abuse. Here we would have a short review on the neuroimaging findings in MA abusers and the children with prenatally exposure to MA, with the focus on electroencephalography (EEG), magnetic resonance imaging (MRI) and functional MRI studies.

Full text

Neuroimaging Findings in Methamphetamine Abusers
Maryam Yasaminshirazi1 and Mehran Ahmadlou1,2*
1Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
2Dynamic Brain Research Group, Tehran, Iran
*Corresponding author: Mehran Ahmadlou, Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands, Tel: 0031649308887; E-
mail: m.ahmadlou@nin.knaw.nl
Received date: March 01, 2016; Accepted date: June 22, 2016; Published date: June 29, 2016
Copyright: © 2016 Yasaminshirazi M, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
Methamphetamine (MA) is a drug which has got a considerable prevalence of abuse in the world. Therefore, it is
of great importance to understand the deficits and problems that it makes in brain, structurally and functionally, in
order to increase knowledge of people about it and help finding better ways of treatments. Neuroimaging techniques
as the most powerful tools to study the brain functions and structures, in the recent decades have been used to find
out the brain deficits caused by the MA abuse. Here we would have a short review on the neuroimaging findings in
MA abusers and the children with prenatally exposure to MA, with the focus on electroencephalography (EEG),
magnetic resonance imaging (MRI) and functional MRI studies.
Keywords: Methamphetamine; Magnetic resonance imaging;
Electroencephalography
Introduction
Methamphetamines are increasingly popular drugs of abuse in
many countries, such as Australia, China, Taiwan, Iran and USA,
causing dramatic individual, social and economic problems [1-4].
Methamphetamine (MA) abusers exhibit decits behaviourally, from
anxiety and impulsivity to perceptual disturbances and hallucinations,
neurochemically, mainly in dopaminergic and serotonergic systems,
and cardiovascularly [1,5-8]. Here we would have a brief review of the
eects of MA abuse on central nervous system based on neuroimaging
ndings. e review consists of the ndings of high temporal
resolution techniques such as electroencephalography (EEG), suitable
to nd changes in temporal dynamics of cortical activities, and high
spatial resolution techniques such as structural and functional
magnetic resonance imaging (MRI and fMRI, respectively), suitable for
detecting and allocating decient cortical and subcortical regions.
EEG
EEG has helped researchers to discover abnormalities of cortical
dynamics in many brain disorders. ere are several studies using
linear and nonlinear analyses, synchronization algorithms, graph-
based algorithms, etc. have reported changes in dierent aspects of the
cortical dynamics and cortical connectivity in MA abusers. Table 1
briey shows the details of the EEG studies reviewed in this article.
Reference
Number of subjects
(Number of males)
Age (year)
mean (Std)
Abuse
Duration (year)
Abstinence
Duration (day) Task Finding
MA/C MA/C Mean (Std) Mean (Std)
Newton et
al. [9] 11/11 (8/8)
32.7 (7.5)/
36.5 (7.3) 11.0 (3.5) 4 (0) no task
increased
delta and
theta power
Newton et
al. [10] 9/10 (7/8)
Age (year)
mean (Std)
At least 0.5 (no
more info.) 4 (0)
working memory and reaction time tasks (N-back,
computerized reaction time battery, and etc.)
increased
theta power
correlated with
accuracy in
working
memory
performance
and reaction
time
Yun et al.
[11] 48/20 all males
37.0 (5.8) /
34.5 (7.7) 11.8 (6.5) 30.5 (27.2) no task
decreased
cortical
complexity
Ahmadlou
et al. [12] 36/36 all males
31.7 (8.8)/
32.7 (6.8) 6.42 (3.13)
Range 7 to 21 days
(no more info.) no task
disrupted
functional
connectivity of
Journal of Addiction Research &
Therapy
Yasaminshirazi and Ahmadlou, J Addict Res Ther
2016, 7:3
http://dx.doi.org/10.4172/2155-6105.1000285
Review Article Open Access
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brain network
in gamma
band
Table 1: Information about the subjects, the performing tasks (if there is any), and the main ndings of the EEG studies, MA: MA Abusers; C:
Control; STD: Standard Deviation.
Newton et al. comparing resting-state EEGs of 11 MA abusers
(abstinent for 4 days) and 11 healthy subjects reported an increased
EEG power at slow frequency bands (delta and theta) in the MA
abusers [9]. Later, in another small sample-size study, Newton et al.
reported a correlation between EEG power at beta frequency band and
episodic memory performance in the MA abusers [10]. Using
approximate entropy (AE) analysis of EEGs, Yun et al. quantied the
degree of cortical complexity in former MA dependent adult males
(abstinent for more than 6 days) and reported decreased cortical
complexity, compared to the healthy adult males [11]. e decreased
cortical complexity may indicate a general reduction of cortical
interactions and functional connectivity. Ahmadlou et al. using
functional connectivity and graph theoretical analysis of resting-state
EEGs, showed that topology of the functional brain connectivity is
disrupted in male MA abusers (abstinent for more than 7 days) in
gamma band, which makes the brain network inecient in the range
of gamma frequency band (30-60 Hz) [12].
MRI
In the last two decades, structural brain abnormalities of MA
abusers have been investigated with dierent volumetric and pattern
analysis methods and the studies have shown correlation of some of
the structural decits with the cognitive/behavioural decits. Table 2
shows a summary of information about the subjects, the performing
tasks (if there is any), and the main ndings of the MRI studies.
Using MRI and surface-based computational image analyses,
ompson et al. found signicant grey matter impairments in
cingulate, limbic, and paralimbic cortices of MA abusers [13]. ey
also reported a signicantly lower hippocampal volumes (compared to
the control group) and signicant white-matter hypertrophy. ere
was a signicant correlation between hippocampal decits and
episodic memory performance (using a test of recall and recognition of
pictures and words). Chang et al. reported enlarged striatum in
recently abstinent methamphetamine abusers (abstinent for more than
7 days) and surprisingly the striatum size was correlated with their
cognitive performance on verbal uency and Grooved Pegboard (the
reason is not clear yet) [14]. Kim et al., comparing short-term (with
mean (Std) of 2.6 (1.6) months) and long-term (with mean (Std) of
30.6 (39.2) months) abstinent MA abusers and healthy subjects in a
decision making task (Wisconsin card sorting task), showed that MA
abusers have prefrontal grey matter decit correlated with total errors
in decision making, which may partially recover with long-term
abstinence [14].
Reference
Number of
subjects
(Number of
males)
Age (year) mean
(Std)
Abuse Duration (year)
mean (Std)
Abstinence
duration
(month) mean
(Std) Task Finding
MA/C MA/C
Thompson et
al. [13] 22/21 (15/10)
31.9 (1.5)/35.3
(1.7) 26.1 (1.8) No abstinence
Episodic memory task
(recall and recognition
of pictures and words)
Gray matter impairments in cingulate,
limbic and paralimbic cortices; lower
hippocampal volumes; white-matter
hypertrophy; hippocampal deficits
correlated with episodic memory
performance
Chang et al.
[14] 50/50
32.1 (7.1)/31.7
(7.4) 9.2 (5.7) 4.0 (6.2)
Battery of
neuropsychological
tests designed to
assess cognitive
functions
Enlarged Striatum correlated with
cognitive performance on verbal
fluency and Grooved Pegboard
Kim et al. [15] 29/20 (27/15)
36.5 (5.5)/33.2
(6.5) 5.3 (3.7) 20.0 (33.5)
Decision making task
(Wisconsin card
sorting)
Prefrontal grey matter deficit
correlated with total errors in decision
making
Table 2: Information about the subjects, the performing tasks (if there is any), and the main ndings of the MRI studies, MA: MA Abusers; C:
Control; Std: Standard Deviation.
e chronic abuse even can aect the brain and cognitive functions
of the children prenatally exposed to MA for at least two thirds of
pregnancy of their MA-dependent mothers. e prenatally MA-
exposed children have decits in visual motor integration, attention,
verbal memory and long-term spatial memory. More surprisingly,
compared to healthy children, they have smaller subcortical structures
(including putamen, globus pallidus, and hippocampus) which are
correlated with their performance on sustained attention and delayed
verbal memory [16].
Citation: Yasaminshirazi M, Ahmadlou M (2016) Neuroimaging Findings in Methamphetamine Abusers. J Addict Res Ther 7: 285. doi:
10.4172/2155-6105.1000285
Page 2 of 5
J Addict Res er
ISSN:2155-6105 JART, an open access journal Volume 7 • Issue 3 • 1000285

fMRI
Using the magnetic properties of deoxygenated and oxygenated
blood, fMRI measures a blood-oxygen-level-dependent (BOLD) signal
[17]. e high spatial resolution and the ability of showing brain
activity from cortical and subcortical regions, makes fMRI as a
powerful tool to study functional brain abnormalities, not only in
resting state, but also during performing dierent tasks. Here we have
a brief review of fMRI nding in functional abnormalities in MA
abusers. Table 3 is shortly representing the information about the
subject, tasks and ndings.
Using fMRI during a double-choice decision making task, Paulus et
al. showed that, compared to the control group, dorsolateral prefrontal
cortex of MA abusers (abstinent for more than 6 days) are less
activated and ventromedial cortex is not activated during the task [18].
e impaired activity of prefrontal cortex is consistent with later
studies during other cognitive tasks [19-21]. Salo et al. showed that a
trial-to-trial reaction time adjustment in a single-trial Stroop task
(which is reduced in MA abusers) has a negative correlation with
prefrontal cortical activity in the MA abusers (abstinent for a
minimum of 3 weeks) [19].
fMRI studies have also shown the decient brain regions in
emotional tasks and understanding others. Orbitofrontal cortex,
temporal poles, and hippocampus in male MA abusers (mean period
of abstinence was 20.5 days) are less activated during processing of
empathy information compared to healthy males [22]. Later Kim et al.
reported a decreased activation in the dorsolateral prefrontal cortex
and insula, and an increased activation in the fusiform gyrus,
hippocampus, parahippocampal gyrus and posterior cingulate cortex
(compared to healthy subjects) during watching visual scenes depicting
fear or threat [23].
References
Number of
subjects
(Number of
males)
Age (year) mean (Std)
Abuse
duration
(year)
Abstinence duration
(month) Task Finding
MA/C MA/C Mean (Std) Mean (Std)
Paulus et al. [18] 10/10 all males 41.1 (2.4)/42.3 (1.9) 19.6 (6.9) 0.75 (0.12) A two-choice prediction
task
No activity of
ventromedial
cortex and lower
activity of
dorsolateral
prefrontal cortex
during decision
making
Salo et al. [19] 12/16 (5/8) 35.7 (7.7)/30.2 (8.9) 13.9 (5.7) 4.1 (2.8) Stroop task
Reduced activity
of right prefrontal
cortex correlated
with trial-to-trial
reaction time
adjustments in
Stroop task
Nestor et al. [20] 10/18 (5/11) 33.5 (9.3)/36.4 (10.4) 8.3 (3.7) 4 to 7 days (no more info) Stroop task
Reduced activity
of prefrontal
cortex in Stroop
task
Kim et al. [22] 19/19 all males 36.0 (range: 31-52)/37.0 (range: 33-42) 13.6 (7.3) 0.68 (0.28) An empathy task
Lower activity of
orbitofrontal
cortex, temporal
poles, and
hippocampus
during empathy
processing
Kim et al. [23] 19/19 (11/12) 36.0 (5.4)/37.0 (3.0) 13.6 (7.3) 0.68 (0.28) An emotion matching task
Decreased
activity of
dorsolateral
prefrontal cortex
and insula, and
an increased
activity of
fusiform gyrus,
hippocampus,
parahippocampa
l gyrus and
posterior
cingulate cortex
during watching
Citation: Yasaminshirazi M, Ahmadlou M (2016) Neuroimaging Findings in Methamphetamine Abusers. J Addict Res Ther 7: 285. doi:
10.4172/2155-6105.1000285
Page 3 of 5
J Addict Res er
ISSN:2155-6105 JART, an open access journal Volume 7 • Issue 3 • 1000285

visual scenes of
fear or threat
Table 3: Information about the subjects, the performing tasks (if there is any), and the main ndings of the fMRI studies, MA: MA Abusers; C:
Control; Std: Standard Deviation.
Unfortunately, prenatally MA-exposure would also cause brain
decits and cognitive impairments. Lu et al. found more diuse
activation in prenatally MA-exposure children during a verbal
memory task (compared to the children exposed only to alcohol) [24].
fMRI can also be used to predict relapse. Interestingly, Clark et al.,
using functional patterns of brain at an early stage of abstinence
predicted which patients later relapse and which ones remain
abstinent. Using fMRI amplitude in right posterior cingulate and
insular cortex, they reached accuracy around 80%.
Conclusion
Neuroimaging techniques have a high potential to nd brain decits
and correlations between the decient brain regions and cognitive/
behavioural performances in MA abusers. However most of the studies
have been done on the abstinent MA abusers and more studies need to
be done to exclude the eects of abstinence. And of course results of
the neuroimaging studies with small sample-sizes should be proved
with larger sample-sizes to be valid enough to be used clinically. e
EEG studies are mostly on the short-term abstinent MA abusers and
it’s necessary to see whether the changes in the brain dynamics is still
there aer a long-term abstinence or not. Moreover, usually MA
abusers are highly stressed are heavy smokers and have lower
educational level. However, unfortunately there is not enough control
to exclude these eects on the neuroimaging ndings [12].
Taking advantages of the neuroimaging techniques, more studies
should be done to nd out the possibilities of predicting the treatment
outcome and relapse of the abstinent MA abusers, which would be
helpful in choosing the most eective therapeutic strategies for each
patient. Another question which is yet dicult to answer by these
studies is about the causality: to what extent and the brain
abnormalities are caused by the toxic eects of drug exposure and to
what extent they may have predated drug-taking and/or predisposed
individuals for the development of drug dependence.
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Citation: Yasaminshirazi M, Ahmadlou M (2016) Neuroimaging Findings in Methamphetamine Abusers. J Addict Res Ther 7: 285. doi:
10.4172/2155-6105.1000285
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J Addict Res er
ISSN:2155-6105 JART, an open access journal Volume 7 • Issue 3 • 1000285

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Citation: Yasaminshirazi M, Ahmadlou M (2016) Neuroimaging Findings in Methamphetamine Abusers. J Addict Res Ther 7: 285. doi:
10.4172/2155-6105.1000285
Page 5 of 5
J Addict Res er
ISSN:2155-6105 JART, an open access journal Volume 7 • Issue 3 • 1000285