Cognitive impairment in individuals currently using methamphetamine

Relationship Between Brain-Derived Neurotrophic Factor and Cognitive Function in Methamphetamine-Dependent Patients

OBJECTIVE

Methamphetamine (METH) is a neurotoxic substance that can induce neurodegeneration in the human brain. Consequently chronic METH use can affect the cognitive functions in METH-dependent patients. In this study, we aimed to identify the relationship between cognitive function and brain-derived neurotrophic factor (BDNF), which reflects the status of neuroadaptive changes, by characterizing the effects on the cognitive function of METH-dependent patients.

METHODS

A total of 38 METH-dependent patients participated in this study. BDNF levels were measured using the enzyme-linked immunosorbent assay. We also examined the clinical features based on the measurements of the Consortium to Establish a Registry for Alzheimer's Disease-Korean version (CERAD-K). Finally, the relationships between various parts of CERAD-K and BDNF were compared with one another.

RESULTS

METH-dependent patients were able to conduct most parts of CERAD-K stably. Among the parts of CERAD-K, only trail-making test part B was correlated with BDNF.

CONCLUSION

The trail-making test is specific for evaluating executive function; therefore, BDNF may play an essential role in detecting neurocognitive functional decline in METH dependence.

Methamphetamine-mediated astrocytic pyroptosis and neuroinflammation involves miR-152-NLRP6 inflammasome signaling axis

Methamphetamine is a widely abused drug associated with significant neuroinflammation and neurodegeneration, mainly through the activation of glial cells and neurons in the central nervous system. This study investigates the role of the astrocyte-specific NOD-like receptor family pyrin domain-containing protein 6 (NLRP6) inflammasome in methamphetamine-induced astrocytic pyroptosis and neuroinflammation. Our findings demonstrate that methamphetamine exposure induces NLRP6-dependent pyroptosis, astrocyte activation, and the release of proinflammatory cytokines in mouse primary astrocytes. Gene silencing of NLRP6 reduces methamphetamine-induced pyroptosis and proinflammatory cytokines release. We also identified miR-152 as a critical upstream regulator of NLRP6, which is downregulated in methamphetamine-exposed astrocytes. Overexpression of miR-152 decreases NLRP6 expression, mitigating methamphetamine-induced pyroptosis and inflammation. In vivo and ex vivo studies in methamphetamine-exposed mice confirmed these results and showed that methamphetamine induces anxiety-like, cognitive impairment, and depression-like behavior, further linking astrocyte-specific NLRP6 signaling to methamphetamine-induced neuroinflammation. This study highlights the potential of targeting the NLRP6 inflammasome in astrocytes as a therapeutic approach to alleviate methamphetamine-induced central nervous system pathology. Further research is warranted to explore clinical applications and identify therapeutic targets for methamphetamine-related neurological disorders.

Genes, Cognition, and Their Interplay in Methamphetamine Use Disorder

Methamphetamine use disorder is a pressing global health issue, often accompanied by significant cognitive deficits that impair daily functioning and quality of life and complicate treatment. Emerging evidence highlights the potential role of genetic factors in methamphetamine use disorder, particularly in association with cognitive function. This review examines the key genetic and cognitive dimensions and their interplay in methamphetamine use disorder. There is converging evidence from several studies that genetic polymorphisms in BDNF, FAAH, SLC18A1, and SLC18A2 are associated with protection against or susceptibility to the disorder. In addition, people with methamphetamine use disorder consistently displayed impairments in cognitive flexibility and inhibitory control compared with people without the disorder. These cognitive domains were associated with reactivity to methamphetamine cues that were positively correlated with total years of methamphetamine use history. Emerging research also suggests that inhibitory control is negatively correlated with lower blood FAAH mRNA levels, while cognitive flexibility positively correlates with higher blood SLC18A2 mRNA levels, highlighting how genetic and cognitive dimensions interact in methamphetamine use disorder. We also include some future directions, emphasizing potential personalized therapeutic strategies that integrate genetic and cognitive insights. By drawing attention to the interplay between genes and cognition, we hope to advance our understanding of methamphetamine use disorder and inform the development of targeted interventions.

The Effect of Modafinil Treatment on Cravings in Methamphetamine Use Disorder

There is a need for treatments that can reduce cravings in methamphetamine use disorder (MUD), which is trending upwards worldwide. The aim of this study was to evaluate the effect of modafinil treatment on substance craving in patients with MUD. The study included 100 patients with MUD who were being treated in an inpatient detoxification center. Patients were divided into two groups as modafinil group (MG) (n = 51) and non-modafinil group (NMG) (n = 49) and compared with each other in terms of sociodemographic data, severity of addiction, change in craving scores on the 1st, 7th and 14th days. The change in craving scores during the first week was found to be significantly greater in the modafinil group (MG) compared to the non-modafinil group (NMG) (p < .001), indicating that modafinil effectively reduced methamphetamine cravings within the first week of treatment. When the changes in craving levels were compared between the groups in the first and second week, the difference between the groups was not statistically significant (p > .05). The mean substance craving scores at hospitalization were higher in MG than NMG (p < .001). Modafinil may be beneficial in the treatment of MUD, especially when used in the first weeks of treatment, especially in patients with higher cravings at baseline.

Single-dose methamphetamine administration impairs ORM retrieval in mice via excessive DA-mediated inhibition of PrLGlu activity

Methamphetamine (METH), an abused psychostimulant, impairs cognition through prolonged or even single-dose exposure, but animal experiments have shown contradictory effects on memory deficits. In this study we investigated the effects and underlying mechanisms of single-dose METH administration on the retrieval of object recognition memory (ORM) in mice. We showed that single-dose METH administration (2 mg/kg, i.p.) significantly impaired ORM retrieval in mice. Fiber photometry recording in METH-treated mice revealed that the activity of prelimbic cortex glutamatergic neurons (PrLGlu) was significantly reduced during ORM retrieval. Chemogenetic activation of PrLGlu or glutamatergic projections from ventral CA1 to PrL (vCA1Glu-PrL) rescued ORM retrieval impairment. Fiber photometry recording revealed that dopamine (DA) levels in PrL of METH-treated mice were significantly increased, and micro-infusion of the D2 receptor (D2R) antagonist sulpiride (0.25 μg/side) into PrL rescued ORM retrieval impairment. Whole-cell recordings in brain slices containing the PrL revealed that PrLGlu intrinsic excitability and basal glutamatergic synaptic transmission were significantly reduced in METH-treated mice, and the decrease in intrinsic excitability was reversed by micro-infusion of Sulpiride into PrL in METH-treated mice. Thus, the impaired ORM retrieval caused by single-dose METH administration may be attributed to reduced PrLGlu activity, possibly due to excessive DA activity on D2R. Selective activation of PrLGlu or vCA1Glu-PrL may serve as a potential therapeutic strategy for METH-induced cognitive dysfunction.

Conflict monitoring and emotional processing in 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine users - A comparative neurophysiological study

In stimulant use and addiction, conflict control processes are crucial for regulating substance use and sustaining abstinence, which can be particularly challenging in social-affective situations. Users of methamphetamine (METH, "Ice") and 3,4-methylenedioxymethamphetamine (MDMA, "Ecstasy") both experience impulse control deficits, but display different social-affective and addictive profiles. We thus aimed to compare the effects of chronic use of the substituted amphetamines METH and MDMA on conflict control processes in different social-affective contexts (i.e., anger and happiness) and investigate their underlying neurophysiological mechanisms. For this purpose, chronic but recently abstinent users of METH (n = 38) and MDMA (n = 42), as well as amphetamine-naïve healthy controls (n = 83) performed an emotional face-word Stroop paradigm, while event-related potentials (ERPs) were recorded. Instead of substance-specific differences, both MDMA and METH users showed smaller behavioral effects of cognitive-emotional conflict processing (independently of emotional valence) and selective deficits in emotional processing of anger content. Both effects were underpinned by stronger P3 ERP modulations suggesting that users of substituted amphetamines employ altered stimulus-response mapping and decision-making. Given that these processes are modulated by noradrenaline and that both MDMA and METH use may be associated with noradrenergic dysfunctions, the noradrenaline system may underlie the observed substance-related similarities. Better understanding the functional relevance of this currently still under-researched neurotransmitter and its functional changes in chronic users of substituted amphetamines is thus an important avenue for future research.

Chan-Chuang and resistance exercise for drug rehabilitation: a randomized controlled trial among Chinese male methamphetamine users

Objective

To examine the health benefits of Chan-Chuang and resistance exercise.

Methods

We deployed an 8-week randomized controlled trial, in which 76 male methamphetamine users were allocated to control (n = 25), Chan-Chuang (n = 26), and residence exercise groups (n = 25). Our primary outcomes were drug craving, mental wellbeing, sleep quality, heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP). Our secondary outcomes were body mass index (BMI), vital capacity, grip strength, balance, and vertical jump.

Results

Chan-Chuang exercise resulted in reduced HR, DBP, and MAP, along with improvements in vital capacity, grip strength, and balance compared to the control group. Resistance exercise reduced SBP and MAP, and also improved vital capacity, grip strength, balance, and vertical jump.

Conclusion

These findings may support the role of Chan-Chuang and resistance exercise in maintaining the physical fitness of methamphetamine users at mandatory detention centers.

Corpus-Based Discourse Analysis of a Reddit Community of Users of Crystal Methamphetamine: Mixed Methods Study

BACKGROUND

Methamphetamine is a highly addictive stimulant that affects the central nervous system. Crystal methamphetamine is a form of the drug resembling glass fragments or shiny bluish-white rocks that can be taken through smoking, swallowing, snorting, or injecting the powder once it has been dissolved in water or alcohol.

OBJECTIVE

The objective of this study is to examine how identities are socially (discursively) constructed by people who use methamphetamine within a subreddit for people who regularly use crystal meth.

METHODS

Using a mixed methods approach, we analyzed 1000 threads (318,422 words) from a subreddit for regular crystal meth users. The qualitative component of the analysis used concordancing and corpus-based discourse analysis to identify discursive themes informed by assemblage theory. The quantitative portion of the analysis used corpus linguistic techniques including keyword analysis to identify words occurring with statistically marked frequency in the corpus and collocation analysis to analyze their discursive context.

RESULTS

Our findings reveal that the subreddit contributors use a rich and varied lexicon to describe crystal meth and other substances, ranging from a neuroscientific register (eg, methamphetamine and dopamine) to informal vernacular (eg, meth, dope, and fent) and commercial appellations (eg, Adderall and Seroquel). They also use linguistic resources to construct symbolic boundaries between different types of methamphetamine users, differentiating between the esteemed category of "functional addicts" and relegating others to the stigmatized category of "tweakers." In addition, contributors contest the dominant view that methamphetamine use inevitably leads to psychosis, arguing instead for a more nuanced understanding that considers the interplay of factors such as sleep deprivation, poor nutrition, and neglected hygiene.

CONCLUSIONS

The subreddit contributors' discourse offers a "set and setting" perspective, which provides a fresh viewpoint on drug-induced psychosis and can guide future harm reduction strategies and research. In contrast to this view, many previous studies overlook the real-world complexities of methamphetamine use, perhaps due to the use of controlled experimental settings. Actual drug use, intoxication, and addiction are complex, multifaceted, and elusive phenomena that defy straightforward characterization.

A Pilot Assessment of the Effects of HIV and Methamphetamine Dependence on Socially Dysregulated Behavior in the Human Behavioral Pattern Monitor

Deficits in social cognition are seen in both people living with HIV (PWH) and people with a history of methamphetamine (METH) dependence. Dually affected individuals may experience additive negative effects on social cognition due to these conditions. We evaluated social cognition in 4 diagnostic groups (HIV-/METH-, HIV-/METH+, HIV+/METH-, HIV+/METH+). First, we used traditional social-emotional functioning assessments, the Difficulties in Emotion Regulation Scale and the Faux Pas Task, to determine any significant effects of METH dependence and HIV on social cognition. Next, we quantified social cognition using the Human Behavioral Pattern Monitor by evaluating social behavior represented by interaction with novel objects. METH dependence significantly affected social-emotional functions and HIV significantly affected on object interactions, however no significant additive effects were observed using these methods. The nuanced relationship between HIV and METH dependence suggests that other factors (i.e., adaptive life skills) likely mediate social cognition-related behaviors.

DSM-5-TR: Rationale, Process, and Overview of Changes

The DSM-5 text revision (DSM-5-TR) is the first published revision of the DSM-5 since its publication in 2013. Like the previous text revision (DSM-IV-TR), the main goal of the DSM-5-TR is to comprehensively update the descriptive text accompanying each DSM disorder on the basis of reviews of the literature over the past 10 years. In contrast to the DSM-IV-TR, in which updates were confined almost exclusively to the text, the DSM-5-TR includes many other changes and enhancements of interest to practicing clinicians, such as the addition of diagnostic categories (prolonged grief disorder, stimulant-induced mild neurocognitive disorder, unspecified mood disorder, and a category to indicate the absence of a diagnosis); the provision of ICD-10-CM symptom codes for reporting suicidal and nonsuicidal self-injurious behavior; modifications, mostly for clarity, of the diagnostic criteria for more than 70 disorders; and updates in terminology (e.g., replacing "neuroleptic medications" with "antipsychotic medications or other dopamine receptor blocking agents" throughout the text and replacing "desired gender" with "experienced gender" in the text for gender dysphoria). Finally, the entire text was reviewed by an Ethnoracial Equity and Inclusion Work Group to ensure appropriate attention to risk factors such as the experience of racism and discrimination, as well as the use of nonstigmatizing language.

Does chronic use of amphetamine-type stimulants impair interference control? - A meta-analysis

In substance use and addiction, inhibitory control is key to ignoring triggers, withstanding craving and maintaining abstinence. In amphetamine-type stimulant (ATS) users, most research focused on behavioral inhibition, but largely neglected the equally important subdomain of cognitive interference control. Given its crucial role in managing consumption, we investigated the relationship between interference control and chronic ATS use in adults. A database search (Pubmed & Web of Science) and relevant reviews were used to identify eligible studies. Effect sizes were estimated with random effects models. Subgroup, meta-regression, and sensitivity analyses explored heterogeneity in effect sizes. We identified 61 studies (53 datasets) assessing interference control in 1873 ATS users and 1905 controls. Findings revealed robust small effect sizes for ATS-related deficits in interference control, which were mainly seen in methamphetamine, as compared to MDMA users. The differential effects are likely due to tolerance-induced dopaminergic deficiencies (presumably most pronounced in methamphetamine users). Similarities between different ATS could be due to noradrenergic deficiencies; but elucidating their functional role in ATS users requires further/more research.

Methamphetamine-induced locomotor sensitization in mice is not associated with deficits in a range of cognitive, affective and social behaviours: interaction with brain-derived neurotrophic factor Val66Met genotype

Chronic methamphetamine (Meth) abuse may induce psychosis similar to that observed in schizophrenia. Brain-derived neurotrophic factor (BDNF) has been implicated in the development of psychosis. We have previously shown long-term protein expression changes in mice treated chronically with Meth depending on BDNF Val66Met genotype. The aim of this study was to investigate if these protein expression changes were associated with differential changes in a range of behavioural paradigms for cognition, anxiety, social and other behaviours. Male and female Val/Val, Val/Met and Met/Met mice were treated with an escalating Meth dose protocol from 6 to 9 weeks of age, with controls receiving saline injections. Several overlapping cohorts were tested in the Y-maze for short-term spatial memory, novel-object recognition test, context and cued fear conditioning, sociability and social preference, elevated plus maze for anxiety-like behaviour and prepulse inhibition (PPI) of acoustic startle. Finally, the animals were assessed for spontaneous exploratory locomotor activity and acute Meth-induced locomotor hyperactivity. Acute Meth caused significantly greater locomotor hyperactivity in mice previously treated with the drug than in saline-pretreated controls. Meth-pretreated female mice showed a mild increase in spontaneous locomotor activity. There were no Meth-induced deficits in any of the other behavioural tests. Val/Met mice showed higher overall social investigation time and lower PPI compared with the Val/Val genotype independent of pretreatment. These results show limited long-term effects of chronic Meth on a range of cognitive, affective and social behaviours despite marked drug-induced locomotor sensitization in mice. There was no interaction with BDNF Val66Met genotype.

Long-term effects of methamphetamine abuse on visual evoked potentials

PURPOSE

To compare visual evoked potential (VEP) components in normal individuals and those with long-term methamphetamine and crystal methamphetamine use.

METHODS

In this study, monocular pattern-reversal VEPs were recorded in 40 methamphetamine and crystal methamphetamine users and 38 normal individuals. Visual stimuli were high-contrast (99%) checkerboard patterns at 15 and 60 min of arc with a reversal rate of 1.53 reversals per second.

RESULTS

A significant difference was seen between the two groups for the P100 peak time for the 60 min of arc checks (p = 0.002, d = 0.75, 4.61% higher peak time in the addicted group) and the 15 min of arc checks (p = 0.004, d = 0.73, 4.78% higher peak time in the addicted group). However, other VEP components were not significantly different between the two groups.

CONCLUSIONS

The higher P100 peak time at both 15 and 60 min of arc in methamphetamine-dependent users reveals that VEPs are highly sensitive for the diagnosis of retinal and visual pathway lesions.

Methamphetamine: burden, mechanism and impact on pregnancy, the fetus, and newborn

While the opioid epidemic has garnered worldwide attention, increasing methamphetamine use has drawn less scrutiny. Methamphetamine is a highly addictive psychostimulant affecting people from all backgrounds and regions. It is a potent vasoconstrictor, is associated with arrhythmias and dilated cardiomyopathy. Cardiovascular disease-related mortality is a leading cause of death in methamphetamine users. Women of childbearing age increasingly use methamphetamine and continue during pregnancy. In the short term, prenatal methamphetamine use is associated with fetal growth restriction and low birth weight in the newborn. Animal studies show reduction in uterine and umbilical blood flow following maternal methamphetamine administration. Based on currently available evidence, prenatal methamphetamine exposure has transient effects on gross motor development, no effect on language and cognition, and modest effects on behavior and executive functioning with poor inhibitory control, which may be attributable to early adversity. Further research is needed to evaluate long-term effects of prenatal methamphetamine exposure.

Cognition during active methamphetamine use versus remission

OBJECTIVE

To evaluate whether cognitive performance in adults with active methamphetamine use (MA-ACT) differs from cognitive performance in adults in remission from MA use disorder (MA-REM) and adults without a history of substance use disorder (CTLs).

METHOD

MA-ACT (n = 36), MA-REM (n = 48), and CTLs (n = 62) completed the Neuropsychological Assessment Battery (NAB).

RESULTS

The MA-ACT group did not perform significantly worse than CTLs on any NAB Index. The MA-REM group performed significantly (p < 0.050) worse than CTLs on the NAB Memory Index. The MA-ACT group performed significantly better than CTLs and the MA-REM group on the Executive Functions Index.

CONCLUSIONS

Some cognitive deficits are apparent during remission from MA use, but not during active use; this may result in clinical challenges for adults attempting to maintain recovery and continue with treatment.

Methamphetamine abuse disturbs the dopaminergic system to impair hippocampal-based learning and memory: An overview of animal and human investigations

Diverse intellectual functions including memory are some important aspects of cognition. Dopamine is a neurotransmitter of the catecholamine family, which contributes to the experience of pleasure and/or emotional states but also plays crucial roles in learning and memory. Methamphetamine is an illegal drug, the abuse of which leads to long lasting pathological manifestations in the brain. Chronic methamphetamine-induced neurotoxicity results in an alteration of various parts of the memory systems by affecting learning processes, an effect attributed to the structural similarities of this drug with dopamine. An evolving field of research established how cognitive deficits in abusers arise and how they could possibly trigger neurodegenerative disorders. Thus, the drugs-induced tenacious neurophysiological changes of the dopamine system trigger cognitive deficits, thereby affirming the influence of this addictive drug on learning, memory and executive function in human abusers. Here we present an overview of the effects of methamphetamine abuse on cognitive functions, dopaminergic transmission and hippocampal integrity as they have been validated in animals and in humans during the past 20 years.

Melatonin protects against methamphetamine-induced Alzheimer's disease-like pathological changes in rat hippocampus

Methamphetamine (METH) is a psychostimulant drug of abuse. METH use is associated with cognitive impairments and neurochemical abnormalities comparable to pathological changes observed in Alzheimer's disease (AD). These observations have stimulated the idea that METH abusers might be prone to develop AD-like signs and symptoms. Melatonin, the pineal hormone, is considered as a potential therapeutic intervention against AD. We thus conducted the present study to explore potential protective roles of melatonin against METH-induced deficits in learning and memory as well as in the appearance of AD-like pathological changes in METH-treated male Wistar rats. We found that melatonin ameliorated METH-induced cognitive impairments in those rats. Melatonin prevented METH-induced decrease in dopamine transporter (DAT) expression in rat hippocampus. Melatonin reversed METH-induced activation of β-arrestin2, reduction of phosphorylation of protein kinase B (Akt) and METH-induced excessive activity of glycogen synthase kinase-3β (GSK3β). Importantly, melatonin inhibited METH-induced changes in the expression of β-site APP cleaving enzyme (BACE1), disintegrin and metalloproteinase 10 (ADAM10), and presenilin 1 (PS1), as well as the reduction of amyloid beta (Aβ)42 production. Immunofluorescence double-labeling demonstrated that melatonin not only prevented the METH-induced loss of DAT but also prevented METH-induced Aβ42 overexpression in the dentate gyrus, CA1, and CA3. Furthermore, melatonin also suppressed METH-induced increase in phosphorylated tau. Significantly, melatonin attenuated METH-induced increase in N-methyl-D-aspartate receptor subtype 2 B (NR2B) protein expression and restored METH-induced reduction of Ca²⁺/calmodulin-dependent protein kinase II (CaMKII). This suggested that melatonin attenuated the toxic effect of METH on the hippocampus involving the amyloidogenic pathway. Taken together, our data suggest that METH abuse may be a predisposing risk factor for AD and that melatonin could serve as a potential therapeutic agent to prevent METH-induced AD like pathology.

Khat and neurobehavioral functions: A systematic review

Background

Khat is a plant that is used for its amphetamine-like stimulant properties. However, although khat is very popular in Eastern Africa, Arabian Peninsula, and the Middle East, there is still a lack of studies researching the possible neurobehavioral impairment derived from khat use.

Methods

A systematic review was conducted to identify studies that assessed the effects of khat use on neurobehavioral functions. MedLine, Scopus, Cochrane, Web of Science and Open Grey literature were searched for relevant publications from inception to December 2020. Search terms included (a) khat and (b) several cognitive domains. References from relevant publications and grey literature were also reviewed to identify additional citations for inclusion.

Results

A total of 142 articles were reviewed, 14 of which met the inclusion criteria (nine human and five rodent studies). Available human studies suggest that long term khat use is associated with significant deficits in several cognitive domains, including learning, motor speed/coordination, set-shifting/response inhibition functions, cognitive flexibility, short term/working memory, and conflict resolution. In addition, rodent studies indicated daily administration of khat extract resulted in dose-related impairments in behavior such as motor hyperactivity and decreased cognition, mainly learning and memory.

Conclusions

The findings presented in this review indicates that long-term khat use may be contributing to an impairment of neurobehavioral functions. However, gaps in literature were detected that future studies could potentially address to better understand the health consequences of khat use.

Glutathione peroxidase-1 and neuromodulation: Novel potentials of an old enzyme

Glutathione peroxidase (GPx) acts in co-ordination with other signaling molecules to exert its own antioxidant role. We have demonstrated the protective effects of GPx,/GPx-1, a selenium-dependent enzyme, on various neurodegenerative disorders (i.e., Parkinson's disease, Alzheimer's disease, cerebral ischemia, and convulsive disorders). In addition, we summarized the recent findings indicating that GPx-1 might play a role as a neuromodulator in neuropsychiatric conditions, such as, stress, bipolar disorder, schizophrenia, and drug intoxication. In this review, we attempted to highlight the mechanistic scenarios mediated by the GPx/GPx-1 gene in impacting these neurodegenerative and neuropsychiatric disorders, and hope to provide new insights on the therapeutic interventions against these disorders.

Inhibition of PLCβ1 signaling pathway regulates methamphetamine self-administration and neurotoxicity in rats

Studies have shown that the central renin-angiotensin system is involved in neurological disorders. Our previous studies have demonstrated that angiotensin II receptor type 1 (AT1R) in the brain could be a potential target against methamphetamine (METH) use disorder. The present study was designed to investigate the underlying mechanisms of the inhibitory effect of AT1R on various behavioural effects of METH. We first examined the effect of AT1R antagonist, candesartan cilexetil (CAN), on behavioural and neurotoxic effects of METH. Furthermore, we studied the role of phospholipase C beta 1 (PLCβ1) blockade behavioural and neurotoxic effects of METH. The results showed that CAN significantly attenuated METH-induced behavioral disorders and neurotoxicity associated with increased oxidative stress. AT1R and PLCβ1 were significantly upregulated in vivo and in vitro. Inhibition of PLCβ1 effectively alleviated METH-induced neurotoxicity and METH self-administration (SA) by central blockade of the PLCβ1 involved signalling pathway. PLCβ1 blockade significantly decreased the reinforcing and motivation effects of METH. PLCβ1 involved signalling pathway, as well as a more specific role of PLCβ1, involved the inhibitory effects of CAN on METH-induced behavioural dysfunction and neurotoxicity. Collectively, our findings reveal a novel role of PLCβ1 in METH-induced neurotoxicity and METH use disorder.

Hippocampal-Dependent Inhibitory Learning and Memory Processes in the Control of Eating and Drug Taking

As manifestations of excessive and uncontrolled intake, obesity and drug addiction have generated much research aimed at identifying common neuroadaptations that could underlie both disorders. Much work has focused on changes in brain reward and motivational circuitry that can overexcite eating and drug-taking behaviors. We suggest that the regulation of both behaviors depends on balancing excitation produced by stimuli associated with food and drug rewards with the behavioral inhibition produced by physiological "satiety" and other stimuli that signal when those rewards are unavailable. Our main hypothesis is that dysregulated eating and drug use are consequences of diet- and drug-induced degradations in this inhibitory power. We first outline a learning and memory mechanism that could underlie the inhibition of both food and drug-intake, and we describe data that identifies the hippocampus as a brain substrate for this mechanism. We then present evidence that obesitypromoting western diets (WD) impair the operation of this process and generate pathophysiologies that disrupt hippocampal functioning. Next, we present parallel evidence that drugs of abuse also impair this same learning and memory process and generate similar hippocampal pathophysiologies. We also describe recent findings that prior WD intake elevates drug self-administration, and the implications of using drugs (i.e., glucagon-like peptide- 1 agonists) that enhance hippocampal functioning to treat both obesity and addiction are also considered. We conclude with a description of how both WD and drugs of abuse could initiate a "vicious-cycle" of hippocampal pathophysiology and impaired hippocampal-dependent behavioral inhibition.

Inflammation but not programmed cell death is activated in methamphetamine-dependent patients: Relevance to the brain function

Animal studies have shown that methamphetamine (MA) induces neurodegeneration through programmed cell death, however, the effects of MA on human brain and the extent of induced neural degeneration is not well understood. Given that the dose and duration of MA administration differ in animals and humans, we evaluated MA effects on active users considering brain damage mechanisms. Nineteen active MA-dependent patients and 18 healthy controls performed the color-word Stroop task, during fMRI and their blood samples were collected. Human enzyme-linked immunosorbent assays (ELISA) and quantitative PCR were applied to measure circulating proteins and miRNAs involved in various programmed cell death pathways (apoptosis, necroptosis, and autophagy), brain damage and neuroinflammation. Results showed the performance deficit in color-word Stroop task in MA abusers as well as higher activations of the right inferior and middle temporal gyri detected by fMRI. Structural MRI revealed increased white matter volume in MA-dependent patients in the superior and medial frontal gyri, and left/right middle temporal gyrus. Molecular analyses detected no significant differences in the plasma levels of the studied proteins and miRNAs of MA-dependent patients and controls except the higher levels of MBP, S100B, and TNFα in MA abusers. Results showed that MA induced physiological and structural changes accompanied by inflammation and release of damage-associated molecules in MA-dependent patients.

Altered brain network topology related to working memory in internet addiction

BACKGROUND AND AIMS

The working memory (WM) ability of internet addicts and the topology underlying the WM processing in internet addiction (IA) are poorly understood. In this study, we employed a graph theoretical framework to characterize the topological properties of the IA brain network in the source cortical space during WM task.

METHODS

A sample of 24 subjects with IA and 23 matched healthy controls (HCs) performed visual 2-back task. Exact Low Resolution Electromagnetic Tomography was adopted to project the pre-processed EEG signals into source space. Subsequently, Lagged phase synchronization was calculated between all pairs of Brodmann areas, the graph theoretical approaches were then employed to estimate the brain topological properties of all participants during the WM task.

RESULTS

We found better WM behavioral performance in IA subjects compared with the HCs. Moreover, compared to the HC group, more integrated and hierarchical brain network was revealed in the IA subjects in alpha band. And altered regional centrality was mainly resided in frontal and limbic lobes. In addition, significant relationships between the IA severity and the significant altered graph indices were found.

CONCLUSIONS

In conclusion, these findings provide evidence to support the notion that altered topological configuration may underline changed WM function observed in IA.

Cognitive deficits in methamphetamine addiction: Independent contributions of dependence and intelligence

BACKGROUND

Methamphetamine's effects on brain function have been associated with cognitive deficits, which have a negative impact on clinical outcomes. However, it remains unclear if cognitive deficits relate to methamphetamine dependence (potentially amenable to abstinence and retraining) or background characteristics, mental health and other drug use. We tested the association between methamphetamine dependence and cognitive performance, while factoring in the impact of background characteristics, depressive symptoms and tobacco, alcohol and cannabis use.

METHOD

The sample comprised 108 treatment-seeking participants who met the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV TR) criteria for methamphetamine dependence and 50 socio-demographically matched controls. We administered a comprehensive neuropsychological test battery (delay discounting, decision making, disinhibition, episodic and working memory) and examined cognitive deficits in methamphetamine users after taking into account socio-demographic characteristics, tobacco, alcohol and cannabis use, and depressive symptoms.

RESULTS

Hierarchical multiple regression analyses showed that methamphetamine dependence was associated with poorer performance in decision-making and disinhibition over and above other predictors, while IQ better explained performance in episodic and working memory. Although duration of methamphetamine use was linked to disinhibition, other patterns of methamphetamine use (including dose and frequency) were not consistently related to performance.

CONCLUSIONS

Methamphetamine dependence impacts inhibitory control and decision-making, whereas lower IQ associates with memory/working memory deficits among methamphetamine users. Findings suggest the need to target disinhibition and impulsive decision-making as part of methamphetamine dependence treatment, while buffering the impact of IQ on memory systems.

Far-infrared Ray-mediated Antioxidant Potentials are Important for Attenuating Psychotoxic Disorders

Far-infrared ray (FIR) is an electromagnetic wave that produces various health benefits against pathophysiological conditions, such as diabetes mellitus, renocardiovascular disorders, stress, and depression etc. However, the therapeutic ap-plication on the FIR-mediated protective potentials remains to be further extended. To achieve better understanding on FIR-mediated therapeutic potentials, we summarized additional findings in the present study that exposure to FIR ameliorates stressful condition, memory impairments, drug dependence, and mitochondrial dysfunction in the central nervous system. In this review, we underlined that FIR requires modulations of janus kinase 2 / signal transducer and activator of transcription 3 (JAK2/STAT3), nuclear factor E2-related factor 2 (Nrf-2), muscarinic M1 acetylcholine receptor (M1 mAChR), dopamine D1 receptor, protein kinase C δ gene, and glutathione peroxidase-1 gene for exerting the protective potentials in response to neuropsychotoxic conditions

Cognition and Related Neural Findings on Methamphetamine Use Disorder: Insights and Treatment Implications From Schizophrenia Research

Despite the prevalence of methamphetamine (meth) use disorder, research on meth is disproportionately scarce compared to research on other illicit drugs. Existing evidence highlights cognitive deficits as an impediment against daily function and treatment of chronic meth use. Similar deficits are also observed in schizophrenia, and this review therefore draws on schizophrenia research by examining similarities and differences between the two disorders on cognition and related neural findings. While meth use disorder and schizophrenia are two distinct disorders, they are highly co-morbid and share impairments in similar cognitive domains and altered brain structure/function. This narrative review specifically identifies overlapping features such as deficits in learning and memory, social cognition, working memory and inhibitory/impulse control. We report that while working memory deficits are a core feature of schizophrenia, such deficits are inconsistently observed following chronic meth use. Similar structural and functional abnormalities are also observed in cortical and limbic regions between the two disorders, except for cingulate activity where differences are observed. There is growing evidence that targeting cognitive symptoms may improve functional outcome in schizophrenia, with evidence of normalized abnormal brain activity in regions associated with cognition. Considering the overlap between meth use disorder and schizophrenia, targeting cognitive symptoms in people with meth use disorder may also improve treatment outcome and daily function.

Evaluation of Microglia/Macrophage Cells from Rat Striatum and Prefrontal Cortex Reveals Differential Expression of Inflammatory-Related mRNA after Methamphetamine

RNA sequencing (RNAseq) can be a powerful tool in the identification of transcriptional changes after drug treatment. RNAseq was utilized to determine expression changes in Fluorescence-activated cell sorted (FACS) CD11b/c+ cells from the striatum (STR) and prefrontal cortex (PFC) of male Sprague-Dawley rats after a methamphetamine (METH) binge dosing regimen. Resident microglia and infiltrating macrophages were collected 2 h or 3 days after drug administration. Gene expression changes indicated there was an increase toward an overall pro-inflammatory state, or M1 polarization, along with what appears to be a subset of cells that differentiated toward the anti-inflammatory M2 polarization. In general, there were significantly more mRNA expression changes in the STR than the PFC and more at 2 h post-binge METH than at 3 days post-binge METH. Additionally, Ingenuity^® Pathway Analysis along with details of RNA expression changes revealed cyclo-oxygenase 2 (COX2)-driven prostaglandin (PG) E2 synthesis, glutamine uptake, and the Nuclear factor erythroid2-related factor 2 (NRF2) canonical pathway in microglia were associated with the binge administration regimen of METH.

Psychostimulant use and the brain

Psychostimulant users are typically young adults. We have conducted a narrative review of neuropsychiatric harms associated with the psychostimulants methamphetamine/amphetamine, cocaine and 3,4-methylenedioxymethamphetamine (MDMA), focusing on epidemiological factors, common clinical presentations, underlying causal mechanisms and treatment options. The major neuropsychiatric harms of psychostimulant use are stroke, neurocognitive impairment, Parkinson's disease, seizures and psychotic illness. These arise through a combination of acute monoamine release, longer-term neurotransmitter effects and indirect effects. These effects are moderated by factors in the individual and in the pattern of substance use. Neuropsychiatric harms associated with psychostimulant use can thus lead to severe long-term impairment.

Toxic effect of khat (Catha edulis) on memory: Systematic review and meta-analysis

BACKGROUND

People use khat (Catha edulis) for its pleasant stimulant effect of physical activity, consciousness, motor, and mental functions. Although there are reports assessing the effect of khat on memory, there was no study based on formal systematic review and meta-analysis.

OBJECTIVE

We have therefore conducted this meta-analysis to determine the level of evidence for the effect of khat (C. edulis Forsk) on memory discrepancy.

METHODS

MEDLINE, Cochrane Library, PubMed, Academic Search Complete, SPORTDiscus, ScienceDirect, Scopus, Web of Science, and Google Scholar were searched to retrieve the papers for this review. Keywords utilized across database search were khat, cat, chat, long-term memory, short-term memory, memory deficit, randomized control trial, and cross-sectional survey. The search was limited to studies in humans and rodents; published in English language.

RESULT

Finding of various studies included in our meta-analysis showed that the effect of acute, and subchronic exposure to khat showed that short-term memory appears to be affected depending on the duration of exposure. However, does not have any effect on long-term memory.

CONCLUSION

Although a number of studies regarding the current topic are limited, the evidenced showed that khat (C. edulis) induced memory discrepancy.

Effects of intrastriatal dopamine D1 or D2 antagonists on methamphetamine-induced egocentric and allocentric learning and memory deficits in Sprague-Dawley rats

RATIONALE

Methamphetamine (MA) is an abused psychostimulant that causes cognitive deficits after chronic use. Neostriatal dopamine receptors play a role in MA monoamine neurotoxicity. Blocking dopamine receptors prior to MA exposure in adult rats attenuates monoamine reductions and reactive gliosis.

OBJECTIVES

We tested whether blocking dopamine receptors protects against cognitive deficits.

METHODS

First, we determined the effects of MA alone versus MA in combination with the dopamine receptor D1 antagonist SCH-23390 or the dopamine receptor D2 antagonist sulpiride on cFos expression and monoamines at the age when rats in the cognitive experiment were to begin testing and monoamines in rats after cognitive testing.

RESULTS

SCH-23390 infused into the neostriatum prior to systemic administration of MA attenuated MA-induced cFos activation while sulpiride induced cFos activation. Two weeks after MA, rats had dopamine and serotonin reductions that were attenuated by each antagonist. Other rats treated the same way, were tested for egocentric learning and memory in the Cincinnati water maze, for navigational strategy in a star water maze, and spatial learning and memory in a Morris water maze. Pre-treatment with SCH-23390 or sulpiride attenuated the effects of MA on egocentric and spatial learning and memory. MA-treated rats showed a shift from an egocentric to a disorganized strategy in the star maze that was less disorganized in groups receiving MA and an antagonist. Post-behavior monoamine reductions remained but were attenuated by the antagonists but not identically to what was seen in rats not behaviorally tested.

CONCLUSIONS

The results show for the first time that dopamine receptors are mediators of MA-induced cognitive deficits.

Thyroid hormone treatment alleviates the impairments of neurogenesis, mitochondrial biogenesis and memory performance induced by methamphetamine

Chronic use of methamphetamine (MA), a neurotoxic psychostimulant, leads to long-lasting cognitive dysfunctions in humans and animal models. Thyroid hormones (THs) have several physiological actions and are crucial for normal behavioral, intellectual and neurological development. Considering the importance of THs in the cognitive processes, the present study was designed to evaluate the therapeutic effects of THs on cognitive and neurological impairments induced by MA. Escalating doses of MA (1-10 mg/kg, IP) were injected twice daily for 10 consecutive days in rats and cognitive functions were evaluated using behavioral tests. The expression of factors involved in neurogenesis (NES and DCX), mitochondrial biogenesis (PGC-1α, NRF-1, and TFAM), neuroinflammation (GFAP, Iba-1, and COX-2) as well as Reelin and NT-3 (synaptic plasticity and neurotrophic factor, respectively) was measured in the hippocampus of MA-treated animals. The effects of three different doses of T4 (20, 40 or 80 μg/kg; intraperitoneally) or T3 (20, 40 or 80 μg/rat; 2.5 μl/nostril; intranasal) treatment, once a day for one week after MA cessation, were assessed in MA-treated rats. After the last behavioral test, serum T4 and T3 levels were measured using radioimmunoassay. The results revealed that repeated escalating regimen of MA impaired cognitive functions concomitant with neurogenesis and synaptic plasticity impairments, mitochondrial dysfunction, and neuroinflammation. T4 or T3 treatment partially decreased the alterations induced by MA. These findings suggest that THs can be considered as potential candidates for the reduction of MA abuse related neurocognitive disturbances.

Naloxone Ameliorates Spatial Memory Deficits and Hyperthermia Induced by a Neurotoxic Methamphetamine Regimen in Male Rats

BACKGROUND

Methamphetamine (METH) as a synthetic psychostimulant is being increasingly recognized as a worldwide problem, which may induce memory impairment. On the other hand, it is well established that naloxone, an opiate antagonist, has some beneficial effects on learning and memory. The present research aimed at evaluating naloxone effects on spatial learning and memory impairment triggered by a neurotoxic regimen of METH in male rats.

MATERIALS AND METHODS

The animals received the subcutaneous (sc) regimen of METH (4×6 mg/kg at 2-h intervals), intraperitoneal (ip) naloxone (4×1 mg/kg at 2-h intervals), or normal saline at four events. The Nal-METH group of rats received four naloxone injections (1 mg/ kg, ip) 30 min before each METH injection (6 mg/kg, sc) at 2-h intervals. Seven days later, they were evaluated for spatial learning and memory in the Morris Water Maze (MWM) task.

RESULTS

METH regimen induced hyperthermia, as well as a poor performance, in the acquisition and retention phases of the task, indicating spatial learning and memory impairment compared to the controls. Naloxone administration (1 mg/kg, ip) before each METH injection led to significant attenuations of both hyperthermia and METH adverse effects on the rat performance in the MWM task.

CONCLUSION

The results revealed that pretreatment with the opiate antagonist naloxone could prevent METH adverse effects on body temperature and memory performance. It seems that the opioidergic system and hyperthermia may, at least partially, be involved in METH effects on spatial memory.

High prevalence of neurocognitive disorders observed among adult people living with HIV/AIDS in Southern Ethiopia: A cross-sectional study

BACKGROUND

Comprehensive care given to people living with HIV/AIDS is improving over time; however, their concurrent cognitive illness is still ignored, under screened and treated particularly in developing countries. And this problem is also striking in Ethiopia. Therefore, the objective of this study was to assess HIV-associated neurocognitive disorders and associated factors among adult people living with HIV/AIDS.

METHODS

An institution based cross sectional study was conducted from April to May, 2017 at Gamo Gofa zone public Hospitals. International HIV Dementia Scale was used to screen HIV associated neurocognitive disorders. Logistic regression analysis was used to assess predictors of neurocognitive disorders.

RESULT

A total of 684 study participants were included in this study with a response rate of 98%. Among them, 56% were females while 44% were males. The mean (±SD) age of the participants was 38.8±8.8years. The screening prevalence of HIV-associated neurocognitive disorder was 67.1% (95% CI; 63.6, 70.5). Body mass index 16 kg/m2 (AOR 4.389 (1.603-12.016)), being married (AOR 0.377 (0.213-0.666), unemployment status (AOR 3.181 (1.752-5.777) and being in WHO clinical stage T3 category/advancing stages of the disease (AOR 3.558 (1.406-9.006) were the key predictors of HIV-associated neurocognitive disorders among people living with HIV/AIDS.

CONCLUSION

In this study the screening prevalence of HIV-associated neurocognitive disorder is higher than the earlier reports in Ethiopia and Africa. This indicates that early screening strategies and policies for cognitive health in people living with HIV/AIDS should be given a top priority.

Possible Role of Cyclic AMP Response Element Binding/Brain-Derived Neurotrophic Factor Signaling Pathway in Mediating the Pharmacological Effects of Duloxetine against Methamphetamine Use-Induced Cognitive Impairment and Withdrawal-Induced Anxiety and Depression in Rats

BACKGROUND

Duloxetine is used for treating depression and anxiety. The current study evaluated the effects of duloxetine against methamphetamine withdrawal-induced anxiety, depression, and motor disturbances and methamphetamine use-induced cognitive impairments.

MATERIALS AND METHODS

Ninety-six adult male rats were used for two independent experiments. Each experiment consisted of Groups 1 and 2 which received normal saline (0.2 ml/rat) and methamphetamine (10 mg/kg) respectively, Groups 3, 4, and 5 received both methamphetamine and duloxetine at doses of 5, 10, and 15 mg/kg, respectively. Groups 6, 7, and 8 received 5, 10, and 15 mg/kg of duloxetine, respectively. All administrations were performed for 21 days. In experiment 1, elevated plus maze (EPM), open-field test (OFT), forced swim test (FST), and tail suspension test (TST) were used to examine anxiety and depression in animals during withdrawal period. In experiment 2, Morris water maze (MWM) test was used to assess the effect of methamphetamine use followed by duloxetine treatment, on learning and memory. In the experiments, the expression of cyclic AMP response element binding (CREB) and brain-derived neurotrophic factor (BDNF) proteins were evaluated using enzyme-linked immunosorbent assay.

RESULTS

In the first experiment, duloxetine at all doses attenuated methamphetamine withdrawal induced-depression, anxiety, and motor disturbances in FST, OFT, EPM, and TST. In the second experiment, duloxetine at all doses attenuated methamphetamine use-induced cognitive impairment in MWM. In both experiments, duloxetine activated cAMP, CREB, and BDNF proteins' expression in methamphetamine-treated rats.

CONCLUSIONS

Duloxetine can protect the brain against methamphetamine withdrawal-induced mood and motor disturbances and can also inhibit methamphetamine-induced cognitive impairment, possibly via cAMP/CREB/BDNF signaling pathway.

Significance of protein kinase C in the neuropsychotoxicity induced by methamphetamine-like psychostimulants

The abuse of methamphetamine (MA), an amphetamine (AMPH)-type stimulant, has been demonstrated to be associated with various neuropsychotoxicity, including memory impairment, psychiatric morbidity, and dopaminergic toxicity. Compelling evidence from preclinical studies has indicated that protein kinase C (PKC), a large family of serine/threonine protein kinases, plays an important role in MA-induced neuropsychotoxicity. PKC-mediated N-terminal phosphorylation of dopamine transporter has been identified as one of the prerequisites for MA-induced synaptic dopamine release. Consistently, it has been shown that PKC is involved in MA (or AMPH)-induced memory impairment and mania-like behaviors as well as MA drug dependence. Direct or indirect regulation of factors related to neuronal plasticity seemed to be critical for these actions of PKC. In addition, PKC-mediated mitochondrial dysfunction, oxidative stress or impaired antioxidant defense system has been suggested to play a role in psychiatric and cognitive disturbance induced by MA (or AMPH). In MA-induced dopaminergic toxicity, particularly PKCδ has been shown to trigger oxidative stress, mitochondrial dysfunction, pro-apoptotic changes, and neuroinflammation. Importantly, PKCδ may be a key mediator in the positive feedback loop composed of these detrimental events to potentiate MA-induced dopaminergic toxicity. This review outlines the role of PKC and its individual isozymes in MA-induced neuropsychotoxicity. Better understanding on the molecular mechanism of PKCs might provide a great insight for the development of potential therapeutic or preventive candidates for MA (or AMPH)-associated neuropsychotoxicity.

Methamphetamine use and cognitive function: A systematic review of neuroimaging research

BACKGROUND

Long-term use of MA has been associated with cognitive dysfunction in several domains. Neuroimaging studies have also reported structural, metabolic, and functional changes in MA users. However, no systematic review has been conducted on those studies in MA users that combined neuroimaging and cognitive tasks.

METHODS

This article systematically reviews correlation between brain imaging measures and cognitive performance in subjects with current and previous history of MA use. Findings are categorized based on cognitive domain.

RESULTS

MA users performed more poorly than controls in all cognitive domains (psychomotor, working memory, attention, cognitive control, and decision- making) and a positive correlation has been repeatedly observed between performance and brain measures (regional volume/density, blood flow, glucose metabolism, FA value, NAA level, and activation) in MA users. Performance in cognitive control was consistently reported to show relationship with brain measures in the PFC and ACC, while decision- making consistently showed correlation with brain measures in the PFC, ACC, and striatum.

CONCLUSIONS

There is solid evidence for brain- behavior relationship in cognitive functioning in MA users, particularly in cognitive control and decision-making. More research with correlation analysis between brain-behavior and MA use parameters is strongly encouraged.

Neuroprotective Effects of Forced Exercise and Bupropion on Chronic Methamphetamine-induced Cognitive Impairment via Modulation of cAMP Response Element-binding Protein/Brain-derived Neurotrophic Factor Signaling Pathway, Oxidative Stress, and Inflammatory Biomarkers in Rats

Background

Forced exercise can act as non-pharmacologic neuroprotective agent. In current study, we tried the involved molecular mechanisms of protective effects of forced exercise against methamphetamine induced neurodegeneration.

Materials and Methods

Forty adult male rats were divided to Group 1 and 2 which received normal saline and methamphetamine (10 mg/kg) respectively for 30 days. Groups 3, 4 and 5 were treated with methamphetamine for first 15 days and then were treated by forced exercise, bupropion (20 mg/kg/day) or combination of them for the following 15 days. Between 26^th and 30^th days, Morris Water Maze (MWM) was used to evaluate the cognition. On day 31, hippocampus was isolated from each rat and oxidative, antioxidant and inflammatory factors also the level of total and phosphorylated forms of cAMP response element-binding protein (CREB) and brain derived neurotrophic factor (BDNF) proteins were also evaluated.

Results

Chronic abuse of methamphetamine could decreases cognition and increase malondialdehyde (MDA), Tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β), while caused decreases in superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) activities all these changes was significant (P < 0.001) in compared to control group while treatment with bupropion, forced exercise and bupropion in combination with forced exercise could prevent all these malicious effects of methamphetamine (P < 0.001). Bupropion, forced exercise and bupropion in combination with forced exercise could activate CREB (both forms) and activates BDNF proteins' expression with P < 0.001 in methamphetamine treated rats.

Conclusions

P-CREB/BDNF signaling pathways might have critical role in forced exercise protective effects against methamphetamine induced neurodegeneration.

Impact of aerobic exercise on cognitive impairment and oxidative stress markers in methamphetamine-dependent patients

This study aimed to investigate whether 12-week moderate-intensity aerobic exercise has beneficial effects on oxidative stress markers in blood and on cognitive functions in patients who have methamphetamine dependence. Serum levels of oxidative stress markers, including total anti-oxidation capability, super oxide dismutase (SOD), catalase (CAT), and methane dicarboxylic aldehyde (MDA), were measured at baseline (all participants) and the 12-week follow-up (methamphetamine-dependent patients). Serum levels of CAT and MDA in methamphetamine-dependent patients (n = 68) were higher than those in healthy controls (n = 35) at baseline. Furthermore, the international shopping list (ISL) task scores of methamphetamine-dependent patients were significantly lower than those of the controls, indicating verbal memory deficits in methamphetamine-dependent patients. Although there were no significant interactions for all cognitive function scores, aerobic exercise improved the processing speed in methamphetamine-dependent patients. Of interest, aerobic exercise significantly attenuated a spontaneous increase in serum MDA levels in methamphetamine-dependent patients after 12-weeks of abstinence. In conclusion, this study showed that methamphetamine-dependent patients with verbal learning and memory deficits have higher serum levels of MDA, and that a 12-week aerobic exercise program may have beneficial effects on the processing speed as well as blood lipid peroxidation in methamphetamine-dependent patients.

Methamphetamine use and future risk for Parkinson's disease: Evidence and clinical implications

BACKGROUND

Methamphetamine use has been posited to be a risk factor for the development of Parkinson's disease (PD) and parkinsonism. The clinical implications of a potential association between methamphetamine use and PD are considered.

METHODS

A review of methamphetamine and PD and parkinsonism was conducted, including evidence from animal models, clinical and population studies.

RESULTS

There is biological plausibility to a link between methamphetamine use and PD. Though clinical and epidemiological evidence in this area is scant, a number of studies suggest that methamphetamine is associated with a moderately increased risk of PD and parkinsonism, and may also lead to premature onset of PD. The long lag time between exposure to methamphetamine and onset of PD, the potential for recovery from neurotoxic effects, and tobacco smoking each may attenuate the association. Individual and drug use characteristics that may modulate a user's risk remain poorly understood.

CONCLUSIONS

The use of methamphetamine may be an initiating event in the development of PD and parkinsonism, in addition to other risk factors that a given individual may hold. Clinicians should be vigilant to signs of prodromal and emerging PD among methamphetamine users. In individuals with premature onset illness, information on current or prior exposure to methamphetamine should be sought.

Family Ruptures, Stress, and the Mental Health of the Next Generation

This paper studies how in utero exposure to maternal stress from family ruptures affects later mental health. We find that prenatal exposure to the death of a maternal relative increases take-up of ADHD medications during childhood and anti-anxiety and depression medications in adulthood. Further, family ruptures during pregnancy depress birth outcomes and raise the risk of perinatal complications necessitating hospitalization. Our results suggest large welfare gains from preventing fetal stress from family ruptures and possibly from economically induced stressors such as unemployment. They further suggest that greater stress exposure among the poor may partially explain the intergenerational persistence of poverty.

Exposure to far-infrared rays attenuates methamphetamine-induced recognition memory impairment via modulation of the muscarinic M1 receptor, Nrf2, and PKC

We demonstrated that activation of protein kinase Cδ (PKCδ) and inactivation of the glutathione peroxidase-1 (GPx-1)-dependent systems are critical for methamphetamine (MA)-induced recognition memory impairment. We also demonstrated that exposure to far-infrared rays (FIR) causes induction of the glutathione (GSH)-dependent system, including induction of the GPx-1 gene. Here, we investigated whether exposure to FIR rays affects MA-induced recognition memory impairment and whether it modulates PKC, cholinergic receptors, and the GSH-dependent system. Because the PKC activator bryostatin-1 mainly induces PKCα, PKCε, and PKCδ, we assessed expression of these proteins after MA treatment. MA treatment selectively increased PKCδ expression and its phosphorylation. Exposure to FIR rays significantly attenuated MA-induced increases in PKCδ phosphorylation. Importantly, bryostatin-1 potentiated MA-induced phosphorylation of PKCδ. MA treatment significantly decreased M1, M3, and M4 muscarinic acetylcholine receptors (mAChRs) and β2 nicotinic acetylcholine receptor expression. Of these, the decrease was most pronounced in M1 mAChR. Exposure to FIR significantly attenuated MA-induced decreases in the M1 mAChR and phospho-ERK_1/2, while it facilitated Nrf2-dependent GSH induction. Dicyclomine, an M1 mAChR antagonist, and l-buthionine-(S, R)-sulfoximine (BSO), an inhibitor of GSH synthesis, counteracted against the protective potentials mediated by FIR. More importantly, the memory-enhancing potential of FIR rays was significantly counteracted by bryostatin-1, dicyclomine, and BSO. Our results suggest that exposure to FIR rays attenuates MA-induced impairment in recognition memory via up-regulation of M1 mAChR, Nrf2-dependent GSH induction, and ERK_1/2 phosphorylation by inhibiting PKCδ phosphorylation by bryostatin-1.

A Single High Dose of Methamphetamine Reduces Monoamines and Impairs Egocentric and Allocentric Learning and Memory in Adult Male Rats

Methamphetamine (MA) alters dopamine markers and cognitive function in heavy users. In rodents, there are MA dosing regimens that induce concordant effects using repeated administration at spaced intervals. These regimens are effective but complicate experiments designed to disentangle the effects of the drug on different brain regions in relation to their cognitive effects because of treatment spacing. In an effort to simplify the model, we tested whether a single dose of MA could induce the same monoamine and cognitive effects as multiple, spaced dosing without affecting survival. Adult male Sprague-Dawley rats were treated with 40 mg/kg MA subcutaneously once and tested starting 2 weeks later. MA-treated rats showed deficits in egocentric navigation in Cincinnati water maze, in spatial navigation in the Morris water maze, and in choosing a consistent problem-solving strategy in the Star water maze when given the option to show a preference. MA-treated rats had persistent dopamine and serotonin reductions in the neostriatum and nucleus accumbens, and serotonin reductions in the hippocampus of the same magnitude as in repetitive treatment models. The data demonstrate that a single dose recapitulates the neurocognitive and monoamine effects of multiple-dose regimens, thereby simplifying the model of MA-induced neurotoxicity.

Effect of exercise versus cognitive behavioural therapy or no intervention on anxiety, depression, fitness and quality of life in adults with previous methamphetamine dependency: a systematic review

BACKGROUND

Methamphetamine (MA) is a highly addictive psychostimulant used by approximately 52 million people worldwide. Chronic MA abuse leads to detrimental physiological and neurological changes, as well as increases in anxiety and depression, and decreases in overall fitness and quality of life. Exercise has been reported to possibly reverse physiological and neurological damage caused by previous MA use, and to reduce anxiety and depression in this population. The aim of this systematic review was to identify, clinically appraise and synthesise the available evidence for the effectiveness of exercise, compared to cognitive behavioural therapy (CBT), standard care or no intervention, on decreasing anxiety and depression and improving fitness and quality of life in previous MA users.

METHODS

Seven computerised databases were searched from inception to May 2017, namely Scopus, Cochrane Library, PubMed/MEDLINE, PEDro, CINAHL, and ScienceDirect. Search terms included exercise, methamphetamine, fitness measures, depression, anxiety and quality of life. Randomised and non-randomised controlled- or clinical trials and pilot studies, published in English, were considered for inclusion. Methodological quality was critically appraised according to the PEDro scale. Heterogeneity across studies regarding control groups and assessment intervals rendered meta analyses inappropriate for this review and results were thus described narratively using text and tables.

RESULTS

Two hundred and fifty-one titles were identified following the initial search, and 14 potentially-relevant titles were selected and the abstracts reviewed. Three studies (two randomised controlled trials and one quasi-experimental pilot) were included, with an average PEDro score of 6.66. Exercise resulted in significantly lower depression and anxiety scores versus CBT (p = 0.001). Balance also significantly improved following exercise versus standard care (p < 0.001); as did vital capacity, hand-grip and one-leg stand with eyes closed. There were significant changes in all subdivisions of the Quality of Life Scale Questionnaire (p < 0.05), except psychology (p = 0.227).

CONCLUSIONS

Level II evidence suggests that exercise is effective in reducing anxiety and depression and improving fitness in previous MA users, and Level III-2 evidence suggests that exercise is beneficial for improving quality of life in this population. Overall recovery in previous MA dependents might be significantly enhanced by including exercise in the rehabilitation process. Further research is required to strengthen these conclusions and to inform policy and health systems effectively.

Self-reported cognitive scales in a US National Survey: reliability, validity, and preliminary evidence for associations with alcohol and drug use

AIMS

To evaluate relationships between measures of cognitive functioning and alcohol or drug use among adults (≥ 18 years) in the US general population.

DESIGN

Two cognitive scales were created based on dimensionality and reliability of self-reported Executive Function Index items. Relationships between the two scales and validators were evaluated. Associations between the cognitive scales and past-year frequency of alcohol or drug use were estimated with adjusted odds ratios (aOR).

SETTING

United States, using the 2012-13 National Epidemiologic Survey on Alcohol and Related Conditions-III, a nationally representative adult sample selected by multi-stage probability sampling.

PARTICIPANTS

36 085 respondents.

MEASUREMENTS

Past-year substance use outcome variables categorized binge drinking, marijuana, cocaine, opioid, sedative/tranquilizer and stimulant use as frequent (at least weekly to daily), infrequent (any to two to three times/month) or no use, assessed by the Alcohol Use Disorder and Associated Disabilities Interview Schedule-5. Key predictors were the two cognitive scales. Construct validators included education and functional impairment. Covariates included age, gender, income and race/ethnicity.

FINDINGS

Nine cognitive items fitted a two-factor model (comparative fit index = 0.973): attention (five items) and executive functioning (four items). Both scales were associated positively with higher education (Ps < 0.001) and negatively with functional impairment (Ps < 0.001), demonstrating construct validity. Poorer attention was associated with frequent and infrequent binge drinking and use of drugs [aOR range = 1.07 (binge drinking) to 1.72 (stimulants), Ps ≤ 0.01]. Poorer executive functioning was associated with frequent binge drinking and use of drugs [aOR range = 1.22 (binge drinking) to 2.03 (cocaine), Ps < 0.001] and infrequent use of all drugs [aOR range = 1.19 (marijuana) to 1.63 (cocaine), Ps < 0.001].

CONCLUSIONS

Impairments in attention and executive functioning are positively associated with substance use in the US general population.

Trace amine-associated receptor 1 regulation of methamphetamine-induced neurotoxicity

Trace amine-associated receptor 1 (TAAR1) is activated by methamphetamine (MA) and modulates dopaminergic (DA) function. Although DA dysregulation is the hallmark of MA-induced neurotoxicity leading to behavioral and cognitive deficits, the intermediary role of TAAR1 has yet to be characterized. To investigate TAAR1 regulation of MA-induced neurotoxicity, Taar1 transgenic knock-out (KO) and wildtype (WT) mice were administered saline or a neurotoxic regimen of 4 i.p. injections, 2h apart, of MA (2.5, 5, or 10mg/kg). Temperature data were recorded during the treatment day. Additionally, striatal tissue was collected 2 or 7days following MA administration for analysis of DA, 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and tyrosine hydroxylase (TH) levels, as well as glial fibrillary acidic protein (GFAP) expression. MA elicited an acute hypothermic drop in body temperature in Taar1-WT mice, but not in Taar1-KO mice. Two days following treatment, DA and TH levels were lower in Taar1-KO mice compared to Taar1-WT mice, regardless of treatment, and were dose-dependently decreased by MA. GFAP expression was significantly increased by all doses of MA at both time points and greater in Taar1-KO compared to Taar1-WT mice receiving MA 2.5 or 5mg/kg. Seven days later, DA levels were decreased in a similar pattern: DA was significantly lower in Taar1-KO compared to Taar1-WT mice receiving MA 2.5 or 5mg/kg. TH levels were uniformly decreased by MA, regardless of genotype. These results indicate that activation of TAAR1 potentiates MA-induced hypothermia and TAAR1 confers sustained neuroprotection dependent on its thermoregulatory effects.