Depression and executive dysfunction contribute to a metamemory deficit among individuals with methamphetamine use disorders

Perirhinal to prefrontal circuit in methamphetamine induced recognition memory deficits

Return to methamphetamine (meth) use is part of an overarching addictive disorder hallmarked by cognitive sequela and cortical dysfunction in individuals who use meth chronically. In rats, long access meth self-administration produces object recognition memory deficits due to drug-induced plasticity within the perirhinal cortex (PRH). PRH projections are numerous and include the medial prefrontal cortex (mPFC). To evaluate the role of the PRH-mPFC reciprocal circuit in novel object recognition memory, a rgAAV encoding GFP-tagged Cre recombinase was infused into the PRH or the mPFC and rats were tested for recognition memory. On test day, one group explored both familiar and novel objects. A second group explored only familiar objects. GFP and Fos expression were visualized in the mPFC or PRH. During exploration, PRH neurons receiving input from the mPFC were equally activated by exploration of novel and familiar objects. In contrast, PRH neurons that provide input to the mPFC were disproportionately activated by novel objects. Further, the percent of Fos + cells in the PRH positively correlated with recognition memory. As such, the flow of communication appears to be from the PRH to the mPFC. In agreement with this proposed directionality, chemogenetic inhibition of the PRH-mPFC circuit impaired object recognition memory, whereas chemogenetic activation in animals with a history of long access meth self-administration reversed the meth-induced recognition memory deficit. This finding informs future work aimed at understanding the role of the PRH, mPFC, and their connectivity in meth associated memory deficits. These data suggest a more complex circuitry governing recognition memory than previously indicated with anatomical or lesion studies.

Methamphetamine exposure and depression-A systematic review and meta-analysis

ISSUES

Methamphetamine use is a public health concern that has been associated with comorbid mental health problems. We aim to better understand the relationship between methamphetamine use and depression by: (i) systematically reviewing and meta-analysing the risks of depression by methamphetamine use; and (ii) investigating the risk of unmeasured confounding.

APPROACH

A systematic review and meta-analysis were conducted following PRISMA guidelines. EMBASE, PsycINFO and PubMed were searched to identify human studies reporting on the association between methamphetamine or amphetamine use and depressive outcomes. The data were summarised narratively and meta-analysed, stratified by cross-sectional and longitudinal estimates. Unmeasured confounding was assessed by E-values analyses.

KEY FINDINGS

From the 6606 studies that came up from the search, 14 eligible studies were included in the narrative review and had data for meta-analysis. A significant association was found between any use of methamphetamine and any depression outcomes in cross-sectional (odds ratio [OR] = 1.66 [95% confidence interval [CI] 1.34, 2.05]) and longitudinal estimates (OR = 1.18 [95% CI 1.08, 1.28]). People with a methamphetamine use disorder had significantly higher odds of depression than those without (OR = 2.80 [95% CI 1.40, 5.90]). The E-values ranged from 1.28 to 6.30 for cross-sectional studies and from 2.37 to 3.21 for longitudinal studies.

CONCLUSION

Based on limited data, people who used methamphetamine have higher odds of depression than people who do not. There were mostly a low to moderate risk of unmeasured confounding in the longitudinal study results. Future longitudinal studies conducted using causal framework methods are warranted.

Strategic regulation of memory in dsyphoria: a quantity-accuracy profile analysis

The mechanisms underlying a tendency among individuals with depression to report personal episodic memories with low specificity remain to be understood. We assessed a sample of undergraduate students with dysphoria to determine whether depression relates to a broader dysregulation of balancing accuracy and informativeness during memory reports. Specifically, we investigated metamnemonic processes using a quantity-accuracy profile approach. Recall involved three phases with increasing allowance for more general, or coarse-grained, responses: (a) forced-precise responding, requiring high precision; (b) free-choice report with high and low penalty incentives on accuracy; (c) a lexical description phase. Individuals with and without dysphoria were largely indistinguishable across indices of retrieval, monitoring, and control aspects of metamemory. The results indicate intact metacognitive processing in young individuals with dysphoria and provide no support for the view that impaired metacognitive control underlies either memory deficits or bias in memory reports that accompany dysphoria.

Impaired Brain-Heart Relation in Patients With Methamphetamine Use Disorder During VR Induction of Drug Cue Reactivity

Methamphetamine use disorder (MUD) is an illness associated with severe health consequences. Virtual reality (VR) is used to induce the drug-cue reactivity and significant EEG and ECG abnormalities were found in MUD patients. However, whether a link exists between EEG and ECG abnormalities in patients with MUD during exposure to drug cues remains unknown. This is important from the therapeutic viewpoint because different treatment strategies may be applied when EEG abnormalities and ECG irregularities are complications of MUD. We designed a VR system with drug cues and EEG and ECG were recorded during VR exposure. Sixteen patients with MUD and sixteen healthy subjects were recruited. Statistical tests and Pearson correlation were employed to analyze the EEG and ECG. The results showed that, during VR induction, the patients with MUD but not healthy controls showed significant [Formula: see text] and [Formula: see text] power increases when the stimulus materials were most intense. This finding indicated that the stimuli are indiscriminate to healthy controls but meaningful to patients with MUD. Five heart rate variability (HRV) indexes significantly differed between patients and controls, suggesting abnormalities in the reaction of patient's autonomic nervous system. Importantly, significant relations between EEG and HRV indexes changes were only identified in the controls, but not in MUD patients, signifying a disruption of brain-heart relations in patients. Our findings of stimulus-specific EEG changes and the impaired brain-heart relations in patients with MUD shed light on the understanding of drug-cue reactivity and may be used to design diagnostic and/or therapeutic strategies for MUD.

Differences in cognitive deficits in patients with methamphetamine and heroin use disorder compared with healthy controls in a Chinese Han population

BACKGROUND AND AIMS

To date, the pattern of heroin- and methamphetamine-induced cognitive impairment is unclear, especially in the Chinese population. The aim of this study was to compare the similarity and heterogeneity of cognitive impairment between heroin and methamphetamine-dependent patients and to link cognitive impairment to drug-related variables.

METHODS

567 pure methamphetamine patients, 78 pure heroin patients and 201 healthy volunteers participated in this study. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was used to assess cognitive function including immediate memory, visuospatial/constructional index, language, attention, delayed memory, and total scores.

RESULTS

Methamphetamine-dependent and heroin-dependent patients performed significantly worse on all RBANS subtest and total scores (all p < 0.05). Moreover, methamphetamine-dependent patients had more delayed memory impairment than heroin-dependent patients (p = 0.02). In addition, some drug-related variables, such as duration of abstinence, age at first drug use, and duration of drug use, were independently associated with memory and visuospatial/constructional index in methamphetamine patients (all p < 0.05). In contrast, none of the drug-related variables were associated with cognitive performance in heroin patients (all p > 0.05).

CONCLUSIONS

Chronic heroin and methamphetamine patients may exhibit different patterns of cognitive deficits.

Implication of thyroid hormone receptors in methamphetamine neurocognitive effects

Methamphetamine (MA) induces neurocognitive effects via several mechanisms. In the present study, we investigated the alteration of thyroid hormone receptor's expression in the context of MA-induced memory impairment and explored the protective effects of exogenous thyroid hormones (THs). Male wistar rats, received increasing regime of MA (1-10mg/kg, intraperitoneal, twice a day for 10 days), were treated with T3 (40μg/rat/day; intranasal, 2.5μl/nostril) or T4 (20µg/kg/day; intraperitoneal) for 7 days after MA cessation. All rats were subjected to novel object recognition memory test and then the mRNA levels of TH nuclear receptors (TRα1 and TRβ1) and seladin-1, an anti-apoptotic factor, and the protein level of TH cell surface receptor (integrin αvβ3) were measured in the hippocampus of rats. Our results showed that MA-induced memory impairment is concomitant with decreased level of TRα1 mRNA. T3 or T4 treatment significantly alleviated MA-induced memory impairment, but had no significant effect on the mRNA levels of TH nuclear receptors. However, T4 treatment significantly increased the protein level of cell surface receptor (av subunit) in MA-treated rats. These findings suggest that MA neurocognitive effects can be associated with impaired TH signaling in the brain and introduce this pathway as a promising therapeutic approach against MA-induced memory impairment.

Neuronal Abnormalities Induced by an Intelligent Virtual Reality System for Methamphetamine Use Disorder

Methamphetamine use disorder (MUD) is a brain disease that leads to altered regional neuronal activity. Virtual reality (VR) is used to induce the drug cue reactivity. Previous studies reported significant frequency-specific abnormalities in patients with MUD during VR induction of drug craving. However, whether those patients exhibit neuronal abnormalities after VR induction that could serve as the treatment target remains unclear. Here, we developed an integrated VR system for inducing drug related changes and investigated the neuronal abnormalities after VR exposure in patients. Fifteen patients with MUD and ten healthy subjects were recruited and exposed to drug-related VR environments. Resting-state EEG were recorded for 5 minutes twice-before and after VR and transformed to obtain the frequency-specific data. Three self-reported scales for measurement of the anxiety levels and impulsivity of participants were obtained after VR task. Statistical tests and machine learning methods were employed to reveal the differences between patients and healthy subjects. The result showed that patients with MUD and healthy subjects significantly differed in, and power changes after VR. These neuronal abnormalities in patients were associated with the self-reported behavioral scales, indicating impaired impulse control. Our findings of resting-state EEG abnormalities in patients with MUD after VR exposure have the translation value and can be used to develop the treatment strategies for methamphetamine use disorder.

Krill Oil Alleviated Methamphetamine-Induced Memory Impairment via the MAPK Signaling Pathway and Dopaminergic Synapse Pathway

Methamphetamine (METH) abuse exerts severe harmful effects in multiple organs, especially the brain, and can induce cognitive dysfunction and memory deficits in humans. Krill oil is rich in polyunsaturated fatty acids, while its effect on METH-induced cognitive impairment and mental disorders, and the underlying mechanism remain unknown. The aim of the present study was to investigate the protective effect of krill oil on METH-induced memory deficits and to explore the molecular mechanisms by using an integrated strategy of bioinformatics analysis and experimental verification. METH-exposed mice were treated with or without krill oil. Learning and memory functions were evaluated by the Morris water maze. The drug–component–target network was constructed in combination with network pharmacology. The predicted hub genes and pathways were validated by the Western blot technique. With krill oil treatment, memory impairment induced by METH was significantly improved. 210 predicted targets constituted the drug–compound–target network by network pharmacology analysis. 20 hub genes such as DRD2, MAPK3, CREB, BDNF, and caspase-3 were filtered out as the underlying mechanisms of krill oil on improving memory deficits induced by METH. The KEGG pathway and GO enrichment analyses showed that the MAPK signaling pathway, cAMP signaling pathway, and dopaminergic synapse pathway were involved in the neuroprotective effects of krill oil. In the hippocampus, DRD2, cleaved caspase-3, and γ-H2AX expression levels were significantly increased in the METH group but decreased in the krill oil–treated group. Meanwhile, krill oil enhanced the expressions of p-PKA, p-ERK1/2, and p-CREB. Our findings suggested that krill oil improved METH-induced memory deficits, and this effect may occur via the MAPK signaling pathway and dopaminergic synapse pathways. The combination of network pharmacology approaches with experimental validation may offer a useful tool to characterize the molecular mechanism of multicomponent complexes.

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.

Cognitive insight, medication adherence and methamphetamine cessation in people enrolled in a pharmacotherapy trial for methamphetamine use

BACKGROUND

The current study examined correlates of cognitive insight in people enrolled in a methamphetamine pharmacotherapy trial; whether cognitive insight at the start of the trial predicted medication adherence and reductions in methamphetamine use during the trial; and, whether insight would remain stable over the trial or improve with reductions in methamphetamine use.

METHODS

A subset of people enrolled in a 12-week randomised placebo-controlled pharmacotherapy trial for methamphetamine dependence completed the Beck Cognitive Insight Scale, comprising subscales for Self-Reflection and Self-Certainty, at baseline (n = 152) and at week 12 (n = 79). Medication adherence was expressed as the percentage of non-missed doses measured using eCAP™ technology. Methamphetamine use days were assessed using the Timeline Followback.

RESULTS

At baseline, greater Self-Reflection was correlated with more severe methamphetamine withdrawal, and hostility, whereas Self-Certainty was correlated with less education and longer duration of methamphetamine use. No relationship was found between BCIS subscales at baseline and medication adherence (Self-Reflection b[SE] = -0.73 [0.43] p = .09; Self-Certainty b[SE] = -0.31 [0.48] p = .52,). Neither BCIS subscale was predictive of reduced methamphetamine use at 12 weeks (Self-Reflection b[SE] = 0.001 [0.01] p = .95 Self-Certainty b[SE] = -0.003 [0.01], p = .74). Self-Reflection decreased over the trial (t = 3.42, p = .001) but this was unrelated to change in methamphetamine use (Self-Reflection, b[SE] = -1.68 [1.16] p = .15) Change in methamphetamine use was found to be a significant predictor of Self-Certainty at 12 weeks (b [SE] = -2.71 [1.16] p = .02).

CONCLUSIONS

We found no evidence that cognitive insight predicted medication adherence or methamphetamine reduction in people engaged in this trial. Ongoing or increased methamphetamine use predicted increased Self-Certainty at 12 weeks.

Basolateral Amygdala Serotonin 2C Receptor Regulates Emotional Disorder-Related Symptoms Induced by Chronic Methamphetamine Administration

Globally, methamphetamine (MA) is the second most abused drug, with psychotic symptoms being one of the most common adverse effects. Emotional disorders induced by MA abuse have been widely reported both in human and animal models; however, the mechanisms underlying such disorders have not yet been fully elucidated. In this study, a chronic MA administration mouse model was utilized to elucidate the serotonergic pathway involved in MA-induced emotional disorders. After 4 weeks of MA administration, the animals exhibited significantly increased depressive and anxious symptoms. Molecular and morphological evidence showed that chronic MA administration reduced the expression of the 5-hydroxytryptamine (5-HT) rate-limiting enzyme, tryptophan hydroxylase 2, in the dorsal raphe and the concentrations of 5-HT and its metabolite 5-hydroxyindoleacetic acid in the basolateral amygdala (BLA) nuclei. Alterations in both 5-HT and 5-HT receptor levels occurred simultaneously in BLA; quantitative polymerase chain reaction, western blotting, and fluorescence analysis revealed that the expression of the 5-HT2C receptor (5-HT_2CR) increased. Neuropharmacology and virus-mediated silencing strategies confirmed that targeting 5-HT_2CR reversed the depressive and anxious behaviors induced by chronic MA administration. In the BLA, 5-HT_2CR-positive cells co-localized with GABAergic interneurons. The inactivation of 5-HT_2CR ameliorated impaired GABAergic inhibition and decreased BLA activation. Thus, herein, for the first time, we report that the abnormal regulation of 5-HT_2CR is involved in the manifestation of emotional disorder-like symptoms induced by chronic MA use. Our study suggests that 5-HT_2CR in the BLA is a promising clinical target for the treatment of MA-induced emotional disorders.

Resveratrol attenuates methamphetamine-induced memory impairment via inhibition of oxidative stress and apoptosis in mice

Methamphetamine (METH) abuse produces serious neurotoxicity to the central nervous system along with long-term cognitive dysfunction. Resveratrol, a natural polyphenol, has broad application prospects in the treatment of neurodegenerative diseases. Therefore, this study was conducted to investigate whether resveratrol might alleviate METH-induced memory deficits in vivo. We found that multiple exposures to METH significantly impaired cognitive functions and caused long-lasting memory deficits (p < .05). Pretreatment of resveratrol (10 or 100 mg/kg) remarkably attenuated METH-induced memory impairment in mice (p < .05). Bioinformatics analysis results showed that resveratrol might alleviate memory deficits by inhibiting METH-induced oxidative damage and apoptosis. Molecular docking showed that resveratrol had hydrogen bonding interactions with Kelch-like ECH associated protein 1 (Keap1), a repressor protein of the classic antioxidant Keap1-Nrf2 pathway. Further results validated oxidative stress parameters, apoptosis, and expression of Keap1 were significantly increased, while the translocation and activation of nuclear factor erythroid 2-related factor 2 (Nrf2) into the nucleus and expression of its downstream proteins were greatly decreased in the hippocampus after METH exposure (p < .05). These changes caused by METH could be prevented by resveratrol (p < .05). Therefore, these findings suggested that the prevention of resveratrol on memory dysfunction induced by METH was possibly related to the activation of the Keap1-Nrf2 pathway and reduction of apoptosis. Supplementation of resveratrol could be a potential treatment for preventing the neurotoxicity of METH in the future. PRACTICAL APPLICATIONS: As one of the worst commonly abused psychostimulants, methamphetamine (METH) addiction produces serious complications including cognitive impairment and memory deficits. Resveratrol is a natural polyphenol that has important nutritional supplements and protective effects in the treatment of many neurodegenerative diseases. In this study, the results of bioinformatics prediction and experimental validation showed that resveratrol might effectively prevent memory impairment via the interaction with Keap1, activation of the Keap1-Nrf2 pathway, and inhibition of DNA damage and apoptotic responses post METH exposure. Therefore, these findings provide new ideas and insights into the application of resveratrol in the treatment of nervous system damage caused by METH.

Mental health outcomes associated with of the use of amphetamines: A systematic review and meta-analysis

BACKGROUND

The use of amphetamines is a global public health concern. We summarise global data on use of amphetamines and mental health outcomes.

METHODS

A systematic review and meta-analysis (CRD 42017081893). We searched Medline, EMBASE, PsycInfo for methamphetamine or amphetamine combined with psychosis, violence, suicidality, depression or anxiety. Included studies were human empirical cross-sectional surveys, case-control studies, cohort studies and randomised controlled trials that assessed the association between methamphetamine and one of the mental health outcomes. Random effects meta-analysis was used to pool results for any use of amphetamines and amphetamine use disorders.

FINDINGS

149 studies were eligible and 59 were included in meta-analyses. There was significant heterogeneity in effects. Evidence came mostly from cross-sectional studies. Any use of amphetamines was associated with higher odds of psychosis (odds ratio [OR] = 2.0, 95%CI 1.3-3.3), violence (OR = 2.2, 95%CI 1.2-4.1; adjusted OR [AOR] = 1.4, 95%CI 0.8-2.4), suicidality OR = 4.4, 95%CI 2.4-8.2; AOR = 1.7, 95%CI 1.0-2.9) and depression (OR = 1.6, 95%CI 1.1-2.2; AOR = 1.3, 95%CI 1.2-1.4). Having an amphetamine use disorder was associated with higher odds of psychosis (OR = 3.0, 95%CI 1.9-4.8; AOR = 2.4, 95%CI 1.6-3.5), violence (OR = 6.2, 95%CI 3.1-12.3), and suicidality (OR = 2.3, 95%CI 1.8-2.9; AOR = 1.5, 95%CI 1.3-1.8).

INTERPRETATION

Methamphetamine use is an important risk factor for poor mental health. High quality population-level studies are needed to more accurately quantify this risk. Clinical responses to methamphetamine use need to address mental health harms.

Cannabinoids Δ9-tetrahydrocannabinol and cannabidiol may be effective against methamphetamine induced mitochondrial dysfunction and inflammation by modulation of Toll-like type-4(Toll-like 4) receptors and NF-κB signaling

The neurodegeneration, neuro-inflammation and mitochondrial dysfunction which occur by methamphetamine (METH) abuse or administration are serious and motivation therapeutic approaches for inhibition of these types of neurodegeneration. As we know, METH through Toll-like receptors (TLRs), specially type 4, and NF-κB signaling pathway causes neuro-inflammation and mitochondrial dysfunction. Neuroprotective approach for management of METH-induced neurodegeneration, inflammation and mitochondrial dysfunction, through a novel neuroprotective agent is continuously being superior to any kind of other therapeutic strategy. Therefore, the clarification, introduction and development of efficacious novel neuroprotective agent are demanded. During recent years, using new neuroprotective agent with therapeutic probability for treatment of METH-induced neuro-inflammation and mitochondrial dysfunction has been astoundingly increased. Previous studies have stated the neuroprotective and anti-inflammatory roles ofcannabinoid derivate such as cannabidiol (CBD) and delta-9-tetrahydrocannabinol (Δ⁹-THC) in multiple neurodegenerative events and diseases. According to literature cannabinoid derivate, by inhibition of TLR4 and activation of NF-κB signaling pathway, exerts their anti-inflammatory and neuroprotective effects and cause mitochondrial biogenesis. Thus we hypothesized that by using cannabinoids in METH dependent subject it would provide neuroprotection against METH-induced neurodegeneration, neuro-inflammation and mitochondrial dysfunction and probably can manage sequels of METH-induced neurochemical abuses via modulation of TLR4/NF-κB signaling pathway. In this article, we tried to discuss our hypothesis regarding the possible role of CBD and Δ⁹-THC, as a potent neuroprotective and anti-inflammatory agents, in inhibition or treatment of METH-induced neurodegeneration, neuro-inflammation and mitochondrial dysfunction through its effects on TLR4/NF-κB signaling pathway.

Study of Methamphetamine Use in Patients Referred to Emergency Ward of a General Hospital at North of Iran in 2017

Background

Acute use of methamphetamine affects the sympathetic system and causes symptoms like tachycardia, hypertension (HTN), tachypnea, peripheral blood vessels constriction, hyperthermia, and mydriasis that can lead to many medical complications. Thus, this study aimed to evaluate the use of methamphetamine, clinical symptoms, and admission causes in patients referred to emergency ward of Imam Khomeini General Hospital in Sari, Iran.

Methods

In this cross-sectional study, 3263 patients were enrolled in the census. The population was patients referred to emergency ward of Imam Khomeini Hospital in Sari, in 2017. Clinical signs and symptoms, test results, primary and definite diagnosis, and patients' status during discharge or referral were extracted from medical records. Statistical analysis was performed using SPSS software.

Findings

A total of 3263 people were enrolled in the study. The prevalence of positive methamphetamine test in patients referred to the emergency department was 1.2%, which was significantly higher in men (P = 0.017). The mean age was 39.9 ± 17.2 years. Methamphetamine users were more likely to be traumatized than the general population. There was a statistically significant difference in seizure (P = 0.003), chest pain (P < 0.001), tachycardia (P < 0.001), palpitation (P < 0.001), HTN (P = 0.002), tachypnea (P = 0.001), visual hallucinations (P = 0.001), auditory hallucinations (P = 0.001), paranoia (P = 0.001), grandiosity (P = 0.035), talkativeness (P = 0.001), suicidal ideation (P < 0.001), homicidal ideation (P = 0.001), violence (P < 0.001), and disorientation (P < 0.001) in positive methamphetamine test group.

Conclusion

Methamphetamine use is more frequent in young men in the second and third decades of life. The most common clinical symptoms in these patients were HTN, chest pain, palpitations, tachycardia, seizure, aggression, anxiety, delusions, and hallucinations.

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.

Withdrawal from chronic treatment with methamphetamine induces anxiety and depression-like behavior in mice

Methamphetamine (METH) is an illicit psychostimulant that is widely abused. After producing extreme pleasure, METH abuse leads to negative emotional states during withdrawal in clinical survey. However, the mood behavioral consequences of withdrawal from chronic METH exposure in animal experiments and related mechanisms have not been clarified yet. The aim of this study was to investigate the anxiety and depression-like phenotype in mice induced by withdrawal from chronic METH treatment and the potential molecular mechanism. We found that withdrawal from chronic METH treatment increased the immobility time during the forced swimming test and decreased central activities in open field test, indicating increased anxiety and depression-like behavior. Additional experiments showed that expression of brain-derived neurotrophic factor (BDNF), phosphorylated tropomyosin receptor kinase B (p-TrkB), phosphorylated extracellular signal-related kinase 1/2 (p-ERK1/2) and phosphorylated cAMP-response element binding protein (p-CREB) were decreased in the hippocampus and prefrontal cortex of mice in METH group and the level of mitogen activated protein kinase phosphatase-1 (MKP-1) was increased. Combined, our data show that withdrawal from chronic METH exposure induces anxiety and depression-like behavior associated with aberrant changes of proteins in BDNF-ERK-CREB pathway, providing new evidence for the involvement of BDNF pathway in the negative emotional states induced by withdrawal from METH.

Bias Toward Drug-Related Stimuli Is Affected by Loading Working Memory in Abstinent Ex-Methamphetamine Users

Background: There is a trade-off between drug-related impulsive process and cognitive reflective process among ex-drug abusers. The present study aimed to investigate the impulsive effects of methamphetamine-related stimuli on working memory (WM) performance by manipulating WM load in abstinent ex-methamphetamine users. Methods: Thirty abstinent ex-methamphetamine users and 30 nonaddict matched control participants were recruited in this study. We used a modified Sternberg task in which participants were instructed to memorize three different sets of methamphetamine-related and non-drug-related words (three, five, or seven words) while performing a secondary attention-demanding task as an interference. Results: Repeated-measures ANOVA revealed that reaction times of abstinent ex-methamphetamine users increased during low WM load (three words) compared to the control group (p = 0.01). No significant differences were observed during high WM loads (five or seven words) (both p's > 0.1). Besides, reaction times of the experimental group during trials with high interference (three, five, or seven words) were not significantly different compared to the control group (p > 0.2). Conclusion: These findings imply that increasing WM load may provide an efficient buffer against attentional capture by salient stimuli (i.e., methamphetamine-related words). This buffer might modify the effect of interference bias. Besides, presenting methamphetamine-related stimuli might facilitate the encoding phase due to bias toward task-relevant stimuli. This finding has an important implication, suggesting that performing concurrent demanding tasks may reduce the power of salient stimuli and thus improve the efficiency of emotional regulation strategies.

Effects of amphetamine exposure during adolescence on behavior and prelimbic cortex neuron activity in adulthood

Repeated exposure to psychostimulants during adolescence produces long-lasting changes in behavior that may be mediated by disrupted development of the mesocorticolimbic dopamine system. Here, we tested this hypothesis by assessing the effects of amphetamine (AMPH) and dopamine receptor-selective drugs on behavior and neuron activity in the prelimbic region of the medial prefrontal cortex (PFC). Adolescent male, Sprague-Dawley rats were given saline or 3 mg/kg AMPH between postnatal day (P) 27 and P45. In Experiment 1, locomotor behavior was assessed during adulthood following challenges with a dopamine D1 (SKF 82958) or D2 (quinpirole) receptor-selective agonist. In Experiment 2, pre-exposed rats were challenged during adulthood with AMPH and a D1 (SKF 83566) or D2 (eticlopride) receptor-selective antagonist. In Experiment 3, the activity of putative pyramidal cells in the prelimbic cortex was recorded as rats behaved in an open-field arena before and after challenge injections with AMPH and one of the antagonists. We found that compared to controls, adolescent pre-exposed rats were more sensitive to the stimulant effects of AMPH and the dopamine receptor agonists, as well as to the ability of the antagonists to reverse AMPH-induced stereotypy. Prelimbic neurons from AMPH pre-exposed rats were also more likely to respond to an AMPH challenge in adulthood, primarily by reducing their activity, and the antagonists reversed these effects. Our results suggest that exposure to AMPH during adolescence leads to enduring adaptations in the mesocorticolimbic dopamine system that likely mediate heightened response to the drug during adulthood.

Effects of methamphetamine abuse on spatial cognitive function

Methamphetamine (MA) abuse has been rising rapidly over the past decade, however, its impact in spatial cognitive function remains unknown. To understand its effect on visuospatial ability and spatial orientation ability, 40 MA users and 40 non-MA users conducted the Simple Reaction Task (Task 1), the Spatial Orientation Task (Task 2), and the Mental Rotation Task (Task 3), respectively. There was no significant difference in either accuracy or reaction time (RT) between 2 groups in Task 1. During Task 2, in comparison with non-MA users, MA users performed poorer on RT, but not in accuracy for foot and hand stimuli. In addition, both non-MA and MA users responded much more quickly to upward stimuli than downward stimuli on vertical surface, however, only non-MA users exhibited leftward visual field advantage in horizontal orientation processing. As for Task 3, MA users exhibited poorer performance and more errors than their healthy counterparts. For each group, linear relationship was revealed between RT and orientation angle, whereas MA abuse led to longer intercept for all stimuli involved. Our findings suggested that MA abuse may lead to a general deficit in the visuospatial ability and the spatial orientation ability with more serious impact in the former.

Impulsivity predicts poorer improvement in quality of life during early treatment for people with methamphetamine dependence

BACKGROUND AND AIMS

Methamphetamine dependence is associated with heightened impulsivity and diminished quality of life, but the link between impulsivity and changes in quality of life during treatment has not been examined. We aimed to investigate how different elements of impulsivity predict change in quality of life in the 6 weeks after engaging in treatment.

DESIGN

Longitudinal, observational cohort study.

SETTING

Public and private detoxification and rehabilitation facilities in metropolitan Melbourne, Australia.

PARTICIPANTS

One hundred and eight individuals with methamphetamine dependence (81 male) tested within 3 weeks of commencing treatment; 80 (74%) were followed-up at 6 weeks.

MEASUREMENTS

The Continuous Performance Test-2 measured impulsive action (cognitive and motor impulsivity); the Delay Discounting Task measured impulsive choice. Quality of life was measured with the World Health Organization Quality of Life Scale-Brief, which includes social, psychological, physical and environment domains. Control variables included age, gender, estimated IQ, depression severity score, methamphetamine dependence severity score, cannabis dependence severity score and treatment modality.

FINDINGS

We found that all three forms of impulsivity were significant predictors of change in the social domain: motor impulsivity (β = -0.54, P = 0.013), cognitive impulsivity (β = -0.46, P = 0.029) and impulsive choice (β = -0.26, P = 0.019). Change in the psychological domain was predicted significantly by motor impulsivity (β = -0.45, P = 0.046). Control variables of age and depression were associated significantly with changes in the physical domain.

CONCLUSIONS

In Australian methamphetamine-dependent individuals, elevated impulsivity predicts lower improvement of social and psychological quality of life in the first 6-9 weeks of treatment.

The impact of cognitive training in substance use disorder: the effect of working memory training on impulse control in methamphetamine users

OBJECTIVES

Impulsivity is a vulnerability trait for poor self-regulation in substance use disorder (SUD). Working memory (WM) training improves impulsivity and self-regulation in psychiatric disorders. Here we test WM training in methamphetamine use disorder (MUD).

METHODS

There are 15 MUD patients receiving inpatient treatment as usual (TAU) and 20 who additionally completed WM cognitive training (CT) and 25 healthy controls (HC). MANCOVA repeated measures analyses examined changes in impulsivity and self-regulation at baseline and after 4 weeks.

RESULTS

Post hoc t tests confirmed that at baseline, feelings of self-control were significantly lower in the MUD (t = 2.001, p = 0.05) and depression was higher (t = 4.980, p = 0.001), as was BIS total impulsivity (t = 5.370, p = 0.001) compared to the HC group. Total self-regulation score was higher in HC than MUD patients (t = 5.370, p = 0.001). CT had a 35% learning rate (R ² = 0.3523, p < 0.05). Compared to follow-up TAU, follow-up CT group had higher self-reported mood scores (t = 2.784, p = 0.01) and higher compared to CT baseline (t = 2.386, p = 0.036). Feelings of self-control were higher in CT than TAU at follow-up (t = 2.736, p = 0.012) and also compared to CT baseline (t = 3.390, p = 0.006), lack of planning significantly improved in CT between baseline and follow-up (t = 2.219, p = 0.048), as did total impulsivity scores (t = 2.085, p = 0.048). Measures of self-regulation were improved in the CT group compared to TAU at follow-up, in total score (t = 2.442, p = 0.038), receiving score (t = 2.314, p = 0.029) and searching score (t = 2.362, p = 0.027). Implementing self-regulation was higher in the CT group compared to TAU (t = 2.373, p = 0.026).

CONCLUSIONS

WM training may improve control of impulsivity and self-regulation in people with MUD.

Abbreviated Goal Management Training Shows Preliminary Evidence as a Neurorehabilitation Tool for HIV-associated Neurocognitive Disorders among Substance Users

OBJECTIVE

Substance use disorders are highly comorbid with and contribute to the increased prevalence of neurocognitive dysfunction observed in HIV infection. Despite their adverse impact on everyday functioning, there are currently no compensatory-based neurorehabilitation interventions validated for use among HIV+ substance users (HIV/SUD). This study examined the effectiveness of goal management training (GMT) alone or GMT as part of a metacognitive training among HIV/SUD individuals with executive dysfunction.

METHODS

Ninety HIV/SUD individuals were randomized to a single 15-min session: (1) GMT (n = 30); (2) GMT plus metacognitive training (neurocognitive awareness; GMT + Meta; n = 30); or (3) active control (n = 30). Following a brief neurocognitive battery and study condition, participants performed a complex laboratory-based function task, Everyday Multitasking Test (Everyday MT), during which metacognition (awareness) was evaluated.

RESULTS

There was an increasing, but non-significant tendency for better Everyday MT performances across study conditions (Control ≤ GMT ≤ GMT + Meta; ps < .08). Post hoc analyses showed that GMT and GMT + Meta groups demonstrated small benefits (d = .20-.27) compared to the control arm but did not differ from one another (ds < .10). When GMT groups were combined, there were significant medium effect size benefits in Everyday MT performance and metacognitive task appraisals as compared to the control condition. Among participants who underwent GMT, benefits were most prominent in persons with poorer pre-training dual-tasking ability, depression, and methamphetamine use disorders (ds = .35-1.04).

CONCLUSIONS

A brief compensatory strategy has benefits for everyday multitasking and metacognition among HIV+ substance users with executive dysfunction. Future work exploring more intensive trainings, potentially complimentary to other restorative approaches and/or pharmacological treatments, is warranted.

Nicotine Administration Attenuates Methamphetamine-Induced Novel Object Recognition Deficits

BACKGROUND

Previous studies have demonstrated that methamphetamine abuse leads to memory deficits and these are associated with relapse. Furthermore, extensive evidence indicates that nicotine prevents and/or improves memory deficits in different models of cognitive dysfunction and these nicotinic effects might be mediated by hippocampal or cortical nicotinic acetylcholine receptors. The present study investigated whether nicotine attenuates methamphetamine-induced novel object recognition deficits in rats and explored potential underlying mechanisms.

METHODS

Adolescent or adult male Sprague-Dawley rats received either nicotine water (10-75 μg/mL) or tap water for several weeks. Methamphetamine (4 × 7.5mg/kg/injection) or saline was administered either before or after chronic nicotine exposure. Novel object recognition was evaluated 6 days after methamphetamine or saline. Serotonin transporter function and density and α4β2 nicotinic acetylcholine receptor density were assessed on the following day.

RESULTS

Chronic nicotine intake via drinking water beginning during either adolescence or adulthood attenuated the novel object recognition deficits caused by a high-dose methamphetamine administration. Similarly, nicotine attenuated methamphetamine-induced deficits in novel object recognition when administered after methamphetamine treatment. However, nicotine did not attenuate the serotonergic deficits caused by methamphetamine in adults. Conversely, nicotine attenuated methamphetamine-induced deficits in α4β2 nicotinic acetylcholine receptor density in the hippocampal CA1 region. Furthermore, nicotine increased α4β2 nicotinic acetylcholine receptor density in the hippocampal CA3, dentate gyrus and perirhinal cortex in both saline- and methamphetamine-treated rats.

CONCLUSIONS

Overall, these findings suggest that nicotine-induced increases in α4β2 nicotinic acetylcholine receptors in the hippocampus and perirhinal cortex might be one mechanism by which novel object recognition deficits are attenuated by nicotine in methamphetamine-treated rats.

Methamphetamine-induced short-term increase and long-term decrease in spatial working memory affects protein Kinase M zeta (PKMζ), dopamine, and glutamate receptors

Methamphetamine (MA) is a toxic, addictive drug shown to modulate learning and memory, yet the neural mechanisms are not fully understood. We investigated the effects of 2 weekly injections of MA (30 mg/kg) on working memory using the radial 8-arm maze (RAM) across 5 weeks in adolescent-age mice. MA-treated mice show a significant improvement in working memory performance 1 week following the first MA injection compared to saline-injected controls. Following 5 weeks of MA abstinence mice were re-trained on a reference and working memory version of the RAM to assess cognitive flexibility. MA-treated mice show significantly more working memory errors without effects on reference memory performance. The hippocampus and dorsal striatum were assessed for expression of glutamate receptors subunits, GluA2 and GluN2B; dopamine markers, dopamine 1 receptor (D1), dopamine transporter (DAT) and tyrosine hydroxylase (TH); and memory markers, protein kinase M zeta (PKMζ) and protein kinase C zeta (PKCζ). Within the hippocampus, PKMζ and GluA2 are both significantly reduced after MA supporting the poor memory performance. Additionally, a significant increase in GluN2B and decrease in D1 identifies dysregulated synaptic function. In the striatum, MA treatment increased cytosolic DAT and TH levels associated with dopamine hyperfunction. MA treatment significantly reduced GluN2B while increasing both PKMζ and PKCζ within the striatum. We discuss the potential role of PKMζ/PKCζ in modulating dopamine and glutamate receptors after MA treatment. These results identify potential underlying mechanisms for working memory deficits induced by MA.