Reaction time variability and related brain activity in methamphetamine psychosis

Neural basis of the attention bias during addiction stroop task in methamphetamine-dependent patients with and without a history of psychosis: an ERP study

Background

Attentional bias plays an important role in sustaining various types of drug addiction. No prior studies examined methamphetamine (MA)-associated psychosis (MAP) relationships between ERP time course and performance on an addiction Stroop task in MA abusers. The aim of the present study was to determine whether MA abusers with (MAP+) or without (MAP-) psychosis exhibit alterations of the ERP during the addiction Stroop task.

Methods

Thirty-one healthy controls (CTRL), 14 MAP-, and 24 MAP+ participants were recruited and completed the addiction Stroop task during EEG recording using 32 electrodes. Group variations were compared on measures of behavioral task performance and event-related potentials (ERP) of performance monitoring (N200, P300, N450). The Barratt impulsiveness scores were analyzed to investigate correlations with ERP changes.

Results

MA-related word stimulus elicited a more negative N200 amplitude over left-anterior electrodes in MAP- abusers; furthermore, a positive association between the N200 amplitude and Barratt attentional scores and non-planning scores was observed, while no such differences were found in MAP+ abusers. There were no significant differences in reaction time (RT) and error rate between each group.

Conclusion

This is the first study to examine psychosis relationships between ERP time course and performance on an addiction Stroop task in MA abusers with or without psychosis. These findings support the association between attentional bias measured by the MA addiction Stroop task and N200 component as well as indicate the possibility of using this cognitive task in combination with ERP technology to detect psychosis factors among abstinent MA abusers.

Effect of methamphetamine on ultraweak photon emission and level of reactive oxygen species in male rat brain

All living cells, including neurons, generate ultra-weak photon emission (UPE) during biological activity, and in particular, in the brain, it has been shown that UPE is correlated with neuronal activity and associated metabolic processes. Various intracellular factors, as well as external factors, can reduce or increase the intensity of UPE. In this study, we have used Methamphetamine (METH) as one potentially effective external factor, which is a substance that has the property of stimulating the central nervous system. METH can impair mitochondrial function by causing toxicity via various pathways, including an increase in the number of mitochondria, hyperthermia, the increased metabolic activity of the brain, and the production of glutamate and excess calcium. In addition to mitochondrial dysfunction, METH alters cellular homeostasis, leading to cell damage and the production of excess ROS. The aim of this study is to measure and compare the UPE intensity and reactive oxygen species (ROS) levels of the prefrontal, motor, and visual cortex before and after METH administration. Twenty male rats were randomly assigned to two groups, the control, and METH groups. In the control group, 2 h after injection of normal saline and without any intervention, and in the experimental group 2 h after IP injection of 20 mg/kg METH, sections were prepared from three areas: prefrontal, motor, and V1-V2 cortex, which were used to evaluate the emission of UPE using a photomultiplier tube (PMT) device and to evaluate the amount of ROS. The results showed that the amount of ROS and UPE in the experimental group in all three areas significantly increased compared to the control group. So, METH increases UPE and ROS in the prefrontal, motor, and visual regions, and there is a direct relationship between UPE intensity and ROS production. Therefore, UPE may be used as a dynamic reading tool to monitor oxidative metabolism in physiological processes related to ROS and METH research. Also, the results of this experiment may create a new avenue to test the hypothesis that the excess in UPE generation may lead to the phenomenon of phosphene and visual hallucinations.

Contributions of Parasympathetic Arousal-Related Activity to Cognitive Performance in Patients With First-Episode Psychosis and Control Subjects

BACKGROUND

Cognitive impairment is integral to the pathophysiology of psychosis. Recent findings implicate autonomic arousal-related activity in both momentary fluctuations and individual differences in cognitive performance. Although altered autonomic arousal is common in patients with first-episode psychosis (FEP), its contribution to cognitive performance is unknown.

METHODS

A total of 24 patients with FEP (46% male, age = 24.31 [SD 4.27] years) and 24 control subjects (42% male, age = 27.06 [3.44] years) performed the Multi-Source Interference Task in-scanner with simultaneous pulse oximetry. First-level models included the cardiac-blood oxygen level-dependent regressor, in addition to task (congruent, interference, and error) and nuisance (motion and CompCor physiology) regressors. The cardiac-blood oxygen level-dependent regressor reflected parasympathetic arousal-related activity and was created by convolving the interbeat interval at each heartbeat with the hemodynamic response function. Group models examined the effect of group or cognitive performance (reaction times × error rate) on arousal-related and task activity, while controlling for sex, age, and framewise displacement.

RESULTS

Parasympathetic arousal-related activity was robust in both groups but localized to different regions for patients with FEP and healthy control subjects. Within both groups, arousal-related activity was significantly associated with cognitive performance across occipital and temporal cortical regions. Greater arousal-related activity in the bilateral prefrontal cortex (Brodmann area 9) was related to better performance in healthy control subjects but not patients with FEP.

CONCLUSIONS

Autonomic arousal circuits contribute to cognitive performance and the pathophysiology of FEP. Arousal-related functional activity is a novel indicator of cognitive ability and should be incorporated into neurobiological models of cognition in psychosis.

Common gray matter loss in the frontal cortex in patients with methamphetamine-associated psychosis and schizophrenia

BACKGROUND AND HYPOTHESIS

Methamphetamine (MA)-associated psychosis has become a public concern. However, its mechanism is not clear. Investigating similarities and differences between MA-associated psychosis and schizophrenia in brain alterations would be informative for neuropathology.

STUDY DESIGN

This study compared gray matter volumes of the brain across four participant groups: healthy controls (HC, n = 53), MA users without psychosis (MA, n = 22), patients with MA-associated psychosis (MAP, n = 34) and patients with schizophrenia (SCZ, n = 33). Clinical predictors of brain alterations, as well as association of brain alterations with psychotic symptoms and attention impairment were further investigated.

STUDY RESULTS

Compared with the HC, the MAP and the SCZ showed similar gray matter reductions in the frontal cortex, particularly in prefrontal areas. Moreover, a stepwise extension of gray matter reductions was exhibited across the MA - MAP - SCZ. Duration of abstinence was associated with regional volumetric recovery in the MAP, while this amendment in brain morphometry was not accompanied with symptom's remission. Illness duration of psychosis was among the predictive factors of regional gray matter reductions in both psychotic groups. Volume reductions were found to be associated with attention impairment in the SCZ, while this association was reversed in the MAP in frontal cortex.

CONCLUSIONS

This study suggested MA-associated psychosis and schizophrenia had common neuropathology in cognitive-related frontal cortices. A continuum of neuropathology between MA use and schizophrenia was tentatively implicated. Illness progressions and glial repairments could both play roles in neuropathological changes in MA-associated psychosis.

The associations of cannabis and methamphetamine use with cognitive performance over the first 2 years of treatment in schizophrenia spectrum disorders

AIM

Cognitive deficits are a core feature of schizophrenia, and comorbid substance use may be a contributory factor. Methamphetamine use has been associated with cognitive impairment in schizophrenia, while associations with cannabis use are less clear-cut. This study aimed to investigate the associations of cannabis and methamphetamine use with cognitive performance in first-episode schizophrenia spectrum disorders over the first 2 years of treatment.

METHODS

This was a longitudinal cohort study in 81 patients treated with flupenthixol decanoate according to a standardized protocol over 24 months. Cognitive performance was assessed with the Measurement and Treatment Research to Improve Cognition in Schizophrenia Cognitive Consensus Battery at four time points, and urine testing for cannabis and methamphetamine was conducted at six time points. We used linear mixed-effect models for repeated measures to assess visit-wise changes in composite cognitive scores in patients (n = 91) compared to matched controls without psychiatric or medical disorders (n = 100). Linear regression models were constructed to examine pre-treatment and end-point effects in patients.

RESULTS

Compared to controls, patients exhibited greater cognitive impairments at baseline, which improved with treatment, but remained significantly lower throughout. The number of positive methamphetamine, but not cannabis, tests predicted less cognitive improvement in patients.

CONCLUSIONS

Our findings suggest a negative association between methamphetamine and cognition, but not cannabis.

Substance-induced psychosis and cognitive functioning: A systematic review

Longitudinal studies of substance-induced psychosis (SIP) suggest that approximately 11-46% of persons will progress to schizophrenia with differential risk of progression depending on the type of substance used. The findings suggest SIP may be a distinct variant of a psychotic disorder, yet SIP is understudied and the disease expression is not well characterized, particularly the cognitive phenotype. There is some evidence for cognitive dysfunction in SIP, but a synthesis of this literature has not been undertaken. We systematically reviewed all empirical research (up to December 31, 2020) that examined cognition in SIP using clinical neuropsychological measures. The cognitive outcomes are summarized by type of SIP (methamphetamine, other stimulants, alcohol, cannabis, undifferentiated). There was evidence for global and domain-specific cognitive dysfunction in SIP compared to controls and non-psychotic persons who use substances. Impairments were of similar magnitude compared to persons with schizophrenia. Delineation of a specific cognitive profile in SIP was precluded by lack of literature with comparable study designs and outcomes. Variation in visual-based cognition may be a distinct feature of SIP, but this requires further investigation. More rigorously controlled studies of cognition in SIP are needed to inform differential diagnosis and identify the unique clinical needs of this population.

Brain dysfunction of methamphetamine-associated psychosis in resting state: Approaching schizophrenia and critical role of right superior temporal deficit

Methamphetamine (MA)-associated psychosis (MAP) is highly debilitating and common among individuals who use the drug, yet the underlying neural mechanism is not clear. This study compared brain functions between patients with MAP and those with schizophrenia during resting state and investigated the effect of brain alteration on the association between MA use and psychosis in patients with MAP. Three groups, including 24 patients with MAP, 17 with schizophrenia in first-episode (SCZ) and 31 healthy controls (HCs), were included after receiving a resting-state functional MRI scan. The severity of psychosis was assessed with Positive and Negative Syndrome Scale (PANSS). Imaging data were analysed using regional homogeneity (ReHo) to measure individual's brain function. Compared with the HC subjects, the MAP and SCZ groups had significantly lower ReHo in the cortical regions including left postcentral cortex, right superior temporal gyrus and right rolandic operculum, while had higher ReHo in the left putamen, with brain dysfunctions being more pronounced in the SCZ group. Among the MAP subjects, a mediating effect of ReHo in the right superior temporal gyrus was found on the association between MA use frequency and PANSS positive score. MAP and schizophrenia had a common trend of brain alteration, with the dysfunction being more pronounced in schizophrenia. This finding implicated that MAP might be a condition with neuropathology approaching schizophrenia. The observed critical role of right superior temporal deficit between MA use and psychosis proposed a potential target for interventions.

Intraindividual reaction time variability as an index of attentional control acts as a moderator of the longitudinal relationships between marital quality and children's externalizing problems

The current study investigated whether trial-to-trial intraindividual reaction time variability (IIRTV), which serves as an index of attentional control fluctuations, moderates the effect of marital quality at 7 years of age on the development of children's externalizing problems from 7 to 9 years of age (N = 197). At the first assessment (T1), a flanker task was administered to children for assessing their IIRTV. The Chinese version of a marital quality questionnaire (Evaluating and Nurturing Relationship Issues, Communication, and Happiness [ENRICH]) and the Chinese version of the Child Behavior Checklist (CBCL) were completed by children's mothers to assess marital quality and children's externalizing problems. At the second and third assessments (T2 and T3), children's externalizing problems were reassessed by their mothers. Growth curve analyses showed that boys' externalizing problems were relatively high and significantly decreased over time, whereas girls' externalizing problems were relatively low and stable. Importantly, the results indicated that boys' IIRTV (but not girls' IIRTV) and parental marital quality interactively predict the concurrent and developmental trajectories of externalizing problems. Specifically, boys with greater IIRTV were found to exhibit a relatively persistent high level of externalizing problems in the context of poor parental marital quality, whereas boys with lower IIRTV were found to exhibit a relatively low level of externalizing problems over time regardless of their parental marital quality. The findings suggest that poorer attentional control indexed by greater IIRTV is a robust predictor of boys' externalizing problems and that better attentional control indexed by lower IIRTV may buffer the negative impact of adverse family environment on the development of boys' externalizing problems.

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.

The COMT rs4680 polymorphism, family functioning and preschoolers' attentional control indexed by intraindividual reaction time variability

Trial-to-trial intraindividual reaction time variability (IIRTV) serves as an index of attentional control and related endogenous brain function. What determinants contribute to preschoolers' attentional control indexed by IIRTV remains unknown. The present study examined how catechol-o-methyltransferase (COMT) rs4680 polymorphism interacted with family functioning (cohesion and adaptability) to impact on preschoolers' attentional control indexed by IIRTV. One hundred forty-four preschool children (M_age  = 4.19, SD = 0.63) completed the flanker task to assess their IIRTV. Their parents were asked to fill out the Family Adaptability and Cohesion Evaluation Scale II to assess family functioning. After controlling for age, socioeconomic status (SES) and mean reaction time, results showed that the COMT rs4680 polymorphism was positively associated with preschoolers' IIRTV at the 5% significance level (p = .02) but not after multiple testing adjustment (p = .08). Moreover the COMT rs4680 polymorphism significantly interacted with family functioning to impact on preschoolers' IIRTV and the interaction effects remained significant after correction for multiple testing (p = .01, ΔR²  = 0.06 in congruent conditions; p = .04, ΔR²  = 0.04 in combined conditions). In addition, the significant interaction between SES and COMT rs4680 polymorphism was also found in the present study (p = .01, ΔR²  = 0.05 in congruent conditions; p = .05, ΔR²  = 0.03 in combined conditions). No sex differences were found in the present sample. The findings of the present study expand our knowledge about the gene × environment underpinnings of children's attentional control and endogenous brain function, and provide evidence for the Vantage Sensitivity model on children's development.

Cognitive state, substance use patterns and outcome after discharge from Kfar Izun, a unique rehabilitation facility

We studied cognitive performance following discharge from a novel rehabilitation facility, treating individuals with psychosis that developed during trips abroad following mandatory military service. Montreal Cognitive Assessment (MoCA), phonetic and semantic fluency, State-Trait Anxiety, and self-Efficiency were administered before discharge, and 3 and 6 months after discharge. Of the 43 participants (30.2% females), 23(54.8%) had cognitive impairment (MoCA <27), and 15(35.7%) had poor phonetic fluency. Anxiety trait and state were high and inversely correlated with self-efficacy (R=-0.48, p = 0.001) and phonetic fluency (R=-0.43, p = 0.004) and was higher among those who experienced physical exposure, females, and those who served in non-combat army units. Six months after discharge, of 32 participants, 28 were working/studying with a 58.1% reduction in smoking and alcohol consumption, and 16 participants stopped substance use. Phonetic fluency improved among the high anxiety state group with no change among the others. High anxiety levels lowered among those who were still using drugs after six months. The anxiety level lowered and 87.1% of the participants were conducting a productive lifestyle at 6 months after discharge, but half still abused cannabis. Bigger sample and longer follow up would be needed to learn more about the impact of rehabilitation.

Neurocognitive intra-individual variability within HIV+ adults with and without current substance use

OBJECTIVE

HIV infection and current substance use (SU) are linked to cognitive and functional deficits, yet findings on their combined effects are mixed. Neurocognitive intraindividual variability, measured as dispersion of scores across a neuropsychological battery, is associated with worse cognitive outcomes and functional deficits among HIV+ adults but has not been studied in the context of HIV+ adults with current SU. We hypothesized that, among HIV+ adults, current SU would be associated with greater dispersion, that greater dispersion would be associated with worse medication adherence, and that this relationship would be worse among substance users.

METHOD

Forty HIV+ adults completed neuropsychological, psychiatric, SU, and medical evaluations and an electronic medication adherence measure. General linear models evaluated the main effect of SU status on neurocognitive dispersion, and models stratified by SU status evaluated the effect of dispersion on medication adherence, adjusting for relevant covariates.

RESULTS

The SU+ group showed greater dispersion than did the SU- group, t(38) = 2.74, p = .049, d = 0.81, but this association did not survive multiple comparisons. Stratified analyses indicated a negative relationship between dispersion and medication adherence among the SU+ group but not in the SU- group; however, this effect was reduced after accounting for depressive symptoms.

CONCLUSIONS

We found preliminary evidence that current SU is associated with greater neurocognitive dispersion among HIV+ adults. SU and neurocognitive dispersion may have a synergistic effect on medication adherence; however, this effect is largely accounted for by depressive symptoms. Future research should examine progression of dispersion in HIV and consequent neurocognitive and functional deficits in those with current SU. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Structural, functional, and neurochemical neuroimaging of methamphetamine-associated psychosis: A systematic review

Methamphetamine is a highly addictive psychostimulant. A subset of methamphetamine users develops methamphetamine-associated psychosis (MAP), which causes poorer prognoses and cognitive function than those with no psychosis (MNP). Comprehensive and integrative summaries of studies utilizing various neuroimaging modalities (structural, functional, and neurochemical) are limited. We conducted a systematic review of literature regarding clinical neuroimaging research published between January 1988 and July 2018 using the PubMed, Web of Science, Scopus, and ScienceDirect databases. Studies comparing the neuroimaging of patients with MAP with healthy controls or patients with MNP or schizophrenia were included to understand the distinct profiles associated with MAP. A total of six structural, three functional, and three neurochemical studies were reviewed. A general trend was identified that showed MAP-related brain alterations were mainly in the frontal lobe (especially the orbitofrontal cortex), striatum, and limbic systems (amygdala and hippocampus). Furthermore, some clinical manifestations, such as the severity of psychotic symptoms and cognitive performance, were correlated with neuroimaging abnormalities. In summary, distinct structural, functional, and neurochemical changes, especially in the frontostriatal circuit and network dynamic systems, play critical roles in the pathophysiology of MAP. Future studies using longitudinal study designs and including individuals with MNP and schizophrenia as controls are warranted.

The impact of the COMT genotype and cognitive demands on facets of intra-subject variability

Intra-Subject Variability (ISV), a potential index of catecholaminergic regulation, is elevated in several disorders linked with altered dopamine function. ISV has typically been defined as reaction time standard deviation. However, the ex-Gaussian and spectral measures capture different aspects and may delineate different underlying sources of ISV; thus reflecting different facets of the construct. We examined the impact of factors associated with dopamine metabolism, namely, Catechol-O-Methyltransferase Val158Met (COMT) genotype and Working Memory (WM) and response-switching on ISV facets in young healthy adults. The Met allele was associated with overall increased variability. The rather exclusive sensitivity of ex-Gaussian tau to frequencies below 0.025 Hz and the quasi-periodic structure of particularly slow responses support the interpretation of tau as low frequency fluctuations of neuronal networks. Sigma, by contrast, may reflect neural noise. Regarding cognitive demands, a WM load-related increase in variability was present for all genotypes and all ISV facets. Contrastingly, ISV facets reacted differently to variations in response-switching as, across genotypes, sigma was elevated for rare target trials whereas tau was elevated for frequent standard trials, particularly for Met homozygotes. Our findings support the significant role of COMT in regulating behavioural ISV with its facetted structure and presumed underlying neural processes.

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 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.

Sleep deprivation as an experimental model system for psychosis: Effects on smooth pursuit, prosaccades, and antisaccades

Current antipsychotic medications fail to satisfactorily reduce negative and cognitive symptoms and produce many unwanted side effects, necessitating the development of new compounds. Cross-species, experimental behavioural model systems can be valuable to inform the development of such drugs. The aim of the current study was to further test the hypothesis that controlled sleep deprivation is a safe and effective model system for psychosis when combined with oculomotor biomarkers of schizophrenia. Using a randomized counterbalanced within-subjects design, we investigated the effects of 1 night of total sleep deprivation in 32 healthy participants on smooth pursuit eye movements (SPEM), prosaccades (PS), antisaccades (AS), and self-ratings of psychosis-like states. Compared with a normal sleep control night, sleep deprivation was associated with reduced SPEM velocity gain, higher saccadic frequency at 0.2 Hz, elevated PS spatial error, and an increase in AS direction errors. Sleep deprivation also increased intra-individual variability of SPEM, PS, and AS measures. In addition, sleep deprivation induced psychosis-like experiences mimicking hallucinations, cognitive disorganization, and negative symptoms, which in turn had moderate associations with AS direction errors. Taken together, sleep deprivation resulted in psychosis-like impairments in SPEM and AS performance. However, diverging somewhat from the schizophrenia literature, sleep deprivation additionally disrupted PS control. Sleep deprivation thus represents a promising but possibly unspecific experimental model that may be helpful to further improve our understanding of the underlying mechanisms in the pathophysiology of psychosis and aid the development of antipsychotic and pro-cognitive drugs.

Psychosis induced by amphetamines

PURPOSE OF REVIEW

The study reviews publications on the use of methamphetamine and amphetamine in relation to psychotic symptoms, substance-induced psychosis, and primary psychosis published between July 2014 and December 2015. The databases MEDLINE, Embase, and PsycINFO were searched using the terms 'amphetamine psychosis' and 'methamphetamine psychosis' for the time period 1 July 2014 to 31 December 2015.

RECENT FINDINGS

There were 37 studies published on the subject during this time period. Risk factors for psychotic symptoms, substance-induced psychosis, and primary psychosis included patterns of drug use, but results also pointed to the importance of nondrug-related vulnerability. Cognitive impairment is associated with both amphetamine use and psychosis, and the impairment among those with amphetamine-induced psychosis resembles that of schizophrenia. At the neuronal level, GABAergic mechanisms may offer some understanding about the association between stimulant use and psychosis. Several different types of antipsychotic medication are effective for treating agitation and psychosis, but drugs with high DRD2 blockade should be used with caution. Some novel treatments are described, but are not sufficiently repeated to be recommended.

SUMMARY

During the past 18 months, studies have been published that cover risk factors, neuronal mechanisms, and treatment. These recent results do not differ from previous understandings, but the role of cognition and GABAergic dysfunction should be further investigated, and knowledge about resilience factors is still scarce. Also, a clearer evidence base for medical treatment of psychosis with concurrent amphetamine use is warranted. VIDEO ABSTRACT.