Methylphenidate and desipramine combined treatment improves PTSD symptomatology in a rat model

D1 dopamine receptor antagonists as a new therapeutic strategy to treat autistic-like behaviours in lysosomal storage disorders

Lysosomal storage disorders characterized by defective heparan sulfate (HS) degradation, such as Mucopolysaccharidosis type IIIA-D (MPS-IIIA-D), result in neurodegeneration and dementia in children. However, dementia is preceded by severe autistic-like behaviours (ALBs), presenting as hyperactivity, stereotypies, social interaction deficits, and sleep disturbances. The absence of experimental studies on ALBs' mechanisms in MPS-III has led clinicians to adopt symptomatic treatments, such as antipsychotics, which are used for non-genetic neuropsychiatric disorders. However, they have limited efficacy in MPS-III and lead to higher extrapyramidal effects, leaving ALBs in MPS-IIIA as an unmet medical need with a significant burden on patients and their families. Using mouse and cellular models of MPS-IIIA, we have previously shown that ALBs result from increased proliferation of mesencephalic dopamine neurons during embryogenesis. In adulthood, MPS-IIIA mice exhibit an imbalance of dopaminergic receptor subtypes, resulting in striatal overstimulation of the D1 dopamine receptor (D1R)-direct pathway, contrasting with a downregulation of the D2 dopamine receptor (D2R)-indirect pathway. In this study, we aimed to provide an evidence-based pharmacological approach for managing ALBs in MPS-IIIA. We hypothesized that rebalancing dopaminergic receptor signalling with a D1R antagonist, rather than a D2 antagonist, would lead to safe and effective treatment. Neither risperidone nor methylphenidate improves ALBs in the MPS-IIIA mouse model, with the former showing increased cataleptic (extrapyramidal-like) side effects compared to littermate wild-type animals. Methylphenidate, however, showed some beneficial effects on neuroinflammation and later manifesting dementia-like behaviours. In contrast, ecopipam, a D1 antagonist already used in the clinic for other neuropsychiatric disorders, rescues ALBs, cognition, D1 hyperactivity, and does not worsen neurodegenerative signs. These results align with recent evidence highlighting the clinical relevance of D1 antagonists for neuropsychiatric disorders and pave the way for their use in managing psychotic symptoms in neurodegenerative disorders such as dementia with Lewy bodies.

Synthetic surprise as the foundation of the psychedelic experience

Psychedelic agents, such as LSD and psilocybin, induce marked alterations in consciousness via activation of the 5-HT2A receptor (5-HT2ARs). We hypothesize that psychedelics enforce a state of synthetic surprise through the biased activation of the 5-HTRs system. This idea is informed by recent insights into the role of 5-HT in signaling surprise. The effects on consciousness, explained by the cognitive penetrability of perception, can be described within the predictive coding framework where surprise corresponds to prediction error, the mismatch between predictions and actual sensory input. Crucially, the precision afforded to the prediction error determines its effect on priors, enabling a dynamic interaction between top-down expectations and incoming sensory data. By integrating recent findings on predictive coding circuitry and 5-HT2ARs transcriptomic data, we propose a biological implementation with emphasis on the role of inhibitory interneurons. Implications arise for the clinical use of psychedelics, which may rely primarily on their inherent capacity to induce surprise in order to disrupt maladaptive patterns.

Geraniol attenuates behavioral and neurochemical impairments by inhibitions of HPA-axis and oxido-inflammatory perturbations in mice exposed to post-traumatic stress disorder

Geraniol is an acyclic isoprenoid monoterpenoid analogue that has been shown to elicit neuroprotective functions, primarily through its ability to stimulate antioxidant and anti-inflammatory systems. An increase in inflammatory cytokines and oxidative stress exacerbate activation hypothalamic-pituitary-adrenal axis (HPA), leading to neurochemical dysfunction, which has important roles in the pathogenesis of post-traumatic disorder (PTSD), a mental health disorder characterized of post-trauma-induced intense fear. The aim of this study was to evaluate the anti-PTSD-like effects and underlying mechanisms of geraniol against single-prolonged-stress (SPS)-induced PTSD in mice. Following concomitant exposure to SPS (triple-paradigm traumatic events) and isolation for 7 days, mice (n = 9) were treated with geraniol (50 and 100 mg/kg, p.o.) or fluoxetine (10 mg/kg, p.o.) from days 8-21. Mice were assessed for behavioral changes. Neurochemical changes, inflammatory, oxido-nitrergic markers, adrenal weight, serum glucose and corticosterone concentrations were assayed. Geraniol inhibits SPS-induced anxiety- and depressive-like features as well as behavioral despair in the depression paradigms. SPS-induced locomotor and memory impairments were also abated by geraniol treatment similarly to fluoxetine. SPS-induced adrenal hypertrophy and increased blood glucose and corticosterone concentrations, were attenuated by the geraniol treatment. Elevated levels of TNF-α and IL-6, and malondialdehyde, nitrite, acetylcholinesterase enzyme were reduced by geraniol. Geraniol also increased glutathione, superoxide-dismutase, and catalase levels as well as dopamine, serotonin concentrations and GABAergic glutamic acid decarboxylase enzyme activity in the striatum, prefrontal cortex and hippocampus in the PTSD-mice relative to SPS control. In conclusion, geraniol attenuates behavioral impairments and neurochemical dysregulations by inhibitions of HPA-axis and oxido-inflammatory perturbations in mice exposed to PTSD.

Discontinuation of antidepressant treatment: a retrospective cohort study on more than 20,000 participants

BACKGROUND

Factors influencing antidepressant treatment discontinuation are poorly understood. In the present study, we aimed to estimate the prevalence of antidepressant treatment discontinuation and identify demographic characteristics, psychiatric comorbidities, and specific side effects associated with treatment discontinuation.

METHODS

We leveraged data from the Australian Genetics of Depression Study (AGDS; N = 20,941) to perform a retrospective cohort study on antidepressant treatment discontinuation. Participants were eligible if they were over 18 years of age, had taken antidepressants in the past 4 years, and provided informed consent.

RESULTS

Among the ten antidepressants studied, the highest discontinuation rates were observed for Mirtazapine (57.3%) and Amitriptyline (51.6%). Discontinuation rates were comparable across sexes except for Mirtazapine, for which women were more likely to discontinue. The two most common side effects, reduced sexual function and weight gain, were not associated with increased odds of treatment discontinuation. Anxiety, agitation, suicidal thoughts, vomiting, and rashes were associated with higher odds for treatment discontinuation, as were lifetime diagnoses of PTSD, ADHD, and a higher neuroticism score. Educational attainment showed a negative (protective) association with discontinuation across medications.

CONCLUSIONS

Our study suggests that not all side effects contribute equally to discontinuation. Common side effects such as reduced sexual function and weight gain may not necessarily increase the risk of treatment discontinuation. Side effects linked to discontinuation can be divided into two groups, psychopathology related and allergy/intolerance.

Insights into the Involvement and Therapeutic Target Potential of the Dopamine System in the Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a neuropsychiatric disease closely related to life-threatening events and psychological stress. Re-experiencing, hyperarousal, avoidance, and numbness are the hallmark symptoms of PTSD, but their underlying neurological processes have not been clearly elucidated. Therefore, the identification and development of drugs for PTSD that targets brain neuronal activities have stalled. Considering that the persistent fear memory induced by traumatic stimulation causes high alertness, high arousal, and cognitive impairment of PTSD symptoms. While the midbrain dopamine system can affect physiological processes such as aversive fear memory learning, consolidation, persistence, and extinction, by altering the functions of the dopaminergic neurons, our viewpoint is that the dopamine system plays a considerable role in the PTSD occurrence and acts as a potential therapeutic target of the disorder. This paper reviews recent findings on the structural and functional connections between ventral tegmental area neurons and the core synaptic circuits involved in PTSD, gene polymorphisms related to the dopamine system that confer susceptibility to clinical PTSD. Moreover, the progress of research on medications that target the dopamine system as PTSD therapies is also discussed. Our goal is to offer some hints for early detection and assist in identifying novel, efficient approaches for treating PTSD.

Attention deficits as a key player in the symptomatology of posttraumatic stress disorder: A review

Posttraumatic stress disorder (PTSD) is a debilitating psychiatric disorder characterized by symptoms such as re-experiencing of the psychotrauma and hyperarousal. Although current literature mainly discusses the emotionally related aspects of these symptoms, studies also highlight the relation between re-experiencing, hyperarousability, and attention deficits, which are associated with poorer daily function and reduced quality of life. This review provides a comprehensive analysis of the existing research on attention deficits among adults with PTSD. A systematic search through five databases resulted in the inclusion of 48 peer-reviewed, English-language articles, describing 49 distinct studies. Using a total of 47 different attentional assessment tools, the majority of studies investigated sustained (n = 40), divided (n = 16), or selective (n = 14) attention. A total of 30 studies (61.2%) found significant correlations between PTSD symptoms and attention deficits, and 10 studies (20.4%) found that higher levels of attention deficits were predictive of worse PTSD symptoms. Moreover, neuroimaging results of six (f)MRI and three EEG studies identified various potential neurobiological pathways involved, including (pre)frontal attention networks. Together, the body of research shows that attention deficits in individuals with PTSD are common and occur in surroundings with emotionally neutral stimuli. Nonetheless, current treatment strategies do not target these attentional difficulties. We propose a novel perspective to PTSD diagnosis and treatment strategies based on attention deficits and their relation with top-down regulation of re-experiencing and subsequent other PTSD symptoms.

Anti-inflammatory properties of commonly used psychiatric drugs

Mental health and neurodevelopmental disorders are extremely common across the lifespan and are characterized by a complicated range of symptoms that affect wellbeing. There are relatively few drugs available that target disease mechanisms for any of these disorders. Instead, therapeutics are focused on symptoms and syndromes, largely driven by neurotransmitter hypotheses, such as serotonin or dopamine hypotheses of depression. Emerging evidence suggests that maternal inflammation during pregnancy plays a key role in neurodevelopmental disorders, and inflammation can influence mental health expression across the lifespan. It is now recognized that commonly used psychiatric drugs (anti-depressants, anti-psychotics, and mood stabilizers) have anti-inflammatory properties. In this review, we bring together the human evidence regarding the anti-inflammatory mechanisms for these main classes of psychiatric drugs across a broad range of mental health disorders. All three classes of drugs showed evidence of decreasing levels of pro-inflammatory cytokines, particularly IL-6 and TNF-α, while increasing the levels of the anti-inflammatory cytokine, IL-10. Some studies also showed evidence of reduced inflammatory signaling via nuclear factor- (NF-)κB and signal transducer and activator of transcription (STAT) pathways. As researchers, clinicians, and patients become increasingly aware of the role of inflammation in brain health, it is reassuring that these psychiatric drugs may also abrogate this inflammation, in addition to their effects on neurotransmission. Further studies are required to determine whether inflammation is a driver of disease pathogenesis, and therefore should be a therapeutic target in future clinical trials.

Emotional and sensory dysregulation as a possible missing link in attention deficit hyperactivity disorder: A review

Attention Deficit Hyperactivity Disorder (ADHD) is a common developmental disorder affecting 5-7% of adults and children. We surveyed the literature to examine ADHD through three pillars: developmental characteristics, symptomatology, and treatment strategies. Firstly, in terms of developmental characterstics, early life stress may increase the risk of developing ADHD symptoms according to animal models' research. Secondly, the current core symptoms of ADHD are comprised of inattention, hyperactivity, and impulsivity. However, the up-to-date literature indicates individuals with ADHD experience emotional and sensory dysregulation as well, which early-life stress may also increase the risk of. Finally, we discuss the therapeutic benefits of methylphenidate on both the current core ADHD symptoms and the sensory and emotional dysregulation found in those with ADHD. In summation, we surveyed the recent literature to analyze (i) the potential role of early-life stress in ADHD development, (ii) the involvement of emotional and sensory dysregulation in ADHD symptomatology and finally, (iii) the therapeutic intervention with methylphenidate, aiming to reduce the potential effect of early life stress in ADHD, and mainly emotional and sensory dysregulation. The apparent but currently less recognized additional symptoms of emotional and sensory dysregulation in ADHD call for further investigation of these possible causes and thus increasing treatments efficacy in individuals with ADHD.

Revealing Unknown Benefits of Existing Medications to Aid the Discovery of New Treatments for Post‐Traumatic Stress Disorder

Objective

To systematically identify novel pharmacological strategies for preventing or treating post‐traumatic stress disorder (PTSD) by leveraging large‐scale analysis of real‐world observational data.

Methods

Using a self‐controlled study design, the association between 1399 medications and the incidence of PTSD across four US insurance claims databases covering commercially insured, Medicare eligible, and Medicaid patients was examined. A validated algorithm for identifying PTSD in claims data was used, and medications were identified by their RxNorm ingredient. Medications used to treat PTSD or its symptoms (e.g., antidepressants, antipsychotics) were excluded. Medications associated with ≥30% reduction in risk of PTSD in ≥2 databases were identified.

Results

A total of 137,182,179 individuals were included in the analysis. Fifteen medications met the threshold criteria for a potential protective effect on PTSD; six were categorized as “primary signals” while the remaining nine were considered “potential signals”. The primary signals include a beta blocker that has been previously studied for PTSD, and five medications used to treat attention‐deficit/hyperactivity disorder. The potential signals include four medications used to treat substance use disorders and five medications used to treat sleep disorders.

Discussion

The medications identified in this analysis provide targets for further research in studies that are designed to examine specific hypotheses regarding these medications and the incidence of PTSD. This work may aid in discovering novel therapeutic approaches to treat PTSD, wherein new and effective treatments are badly needed.

Four large US‐based administrative claims databases were used to analyze the association between all marketed prescription medications and the outcome of incident post‐traumatic stress disorder (PTSD)

Of the 1399 medications examined, there were 15 that met the strict filtering criteria for showing consistent, moderate‐to‐strong, protective effects against the outcome

Medications fell into four main classes: (1) a beta blocker (propranolol), (2) five medications used to treat attention‐deficit/hyperactivity disorder (ADHD), (3) four medications used to treat substance use disorders and (4) five medications used to treat sleep disorders

These findings identify rational starting points for future hypothesis‐driven research to explore these associations in greater detail

Repeated cocaine exposure prior to fear conditioning induces persistency of PTSD-like symptoms and enhancement of hippocampal and amygdala cell density in male rats

Pre- and post-trauma drug use can interfere with recovery from post-traumatic stress disorder (PTSD). However, the biological underpinnings of this interference are poorly understood. Here we examined the effect of pre-fear conditioning cocaine self-administration on PTSD-like symptoms in male rats, and defined impairment of fear extinction as difficulty to recover from PTSD. We also examined cell density changes in brain regions suspected of being involved in resistance to PTSD recovery. Before footshock stress testing, rats were trained to self-administer cocaine during 20 consecutive days, after which they were exposed to footshocks, while other rats continued to self-administer cocaine until the end of the experiment. Upon assessment of three PTSD-like symptoms (fear during situational reminders, anxiety-like behavior, and impairment of recognition memory) and fear extinction learning and memory, changes in cell density were measured in the medial prefrontal cortex, hippocampus, and amygdala. Results show that pre-footshock cocaine exposure did not affect fear during situational reminders. Fear conditioning did not lead to an increase in cocaine consumption. However, in footshock stressed rats, cocaine induced a reduction of anxiety-like behavior, an aggravation of recognition memory decline, and an impairment of extinction memory. These behavioral alterations were associated with increased cell density in the hippocampal CA1, CA2, and CA3 regions and basolateral amygdala, but not in the medial prefrontal cortex. Our findings suggest that enhancement of cell density in the hippocampus and amygdala may be changes associated with drug use, interfering with PTSD recovery.

Mini-review: A possible role for galanin in post-traumatic stress disorder

Several neuroendocrine systems have been implicated in post-traumatic stress disorder, including the mesocortical and mesolimbic dopamine, the norepinephrine, the β-endorphin, the serotonin, and the oxytocin systems. The interaction between these different systems remains, however, largely unknown and a generally accepted unifying theory is thus far lacking. In this review, we suggest that galanergic suppression of dopaminergic neurons in the ventral tegmental may constitute the missing link in a post-traumatic feedback loop. In addition, we address the literature on the negative cross-antagonism in this brain region between the galanin 1 and μ-opioid receptors, which suggests that behavioural patterns which stimulate β-endorphin, a natural μ-opioid receptors ligand, secretion may provide novel avenues for the treatment and prevention of PTSD, as well as for recruitment, training, and leadership processes in high-stress/high-risk professions such as the military, first responders and the police.

Dopamine, endocannabinoids and their interaction in fear extinction and negative affect in PTSD

There currently exist few frameworks for common neurobiology between reexperiencing and negative cognitions and mood symptoms of PTSD. Adopting a dopaminergic framework for PTSD unites many aspects of unique symptom clusters, and this approach also links PTSD symptomology to common comorbidities with a common neurobiological deficiency. Here we review the dopamine literature and incorporate it with a growing field of research that describes both the contribution of endocannabinoids to fear extinction and PTSD, as well as the interactions between dopaminergic and endocannabinoid systems underlying this disorder. Based on current evidence, we outline an early, preliminary model that links re-experiencing and negative cognitions and mood in PTSD by invoking the interaction between endocannabinoid and dopaminergic signalling in the brain. These interactions between PTSD, dopamine and endocannabinoids may have implications for future therapies for treatment-resistant and comorbid PTSD patients.

Prolonged Exposure Therapy: A Case of Comorbid PTSD, ADHD, and GAD

This case study displays the successful application of Prolonged Exposure (PE) for a client with diagnoses of Posttraumatic Stress Disorder (PTSD), Attention Deficit Hyperactivity Disorder (ADHD), and Generalized Anxiety Disorder (GAD). To our knowledge ADHD has not been examined as a predictor or moderator of PE outcomes. As such, practitioners have precious little information about how to proceed in such cases, which highlights the importance of careful individual assessment and case conceptualization. There is also a dearth of information on the effects of combining PE (a research-supported psychological intervention for PTSD) with psychostimulant medication (a research-supported pharmacological intervention for ADHD). The present case study illustrates a positive synergy between psychostimulant treatment and PE. The unique adjustments made to deliver services (including in the face of COVID-19) are described as well as what this case suggests about the effects of psychostimulant use on PTSD symptoms and the new learning that occurs during PE.

Methylphenidate Attenuates the Cognitive and Mood Alterations Observed in Mbnl2 Knockout Mice and Reduces Microglia Overexpression

Myotonic dystrophy type 1 (DM1) is a multisystem disorder affecting muscle and central nervous system (CNS) function. The cellular mechanisms underlying CNS alterations are poorly understood and no useful treatments exist for the neuropsychological deficits observed in DM1 patients. We investigated the progression of behavioral deficits present in male and female muscleblind-like 2 (Mbnl2) knockout (KO) mice, a rodent model of CNS alterations in DM1, and determined the biochemical and electrophysiological correlates in medial prefrontal cortex (mPFC), striatum and hippocampus (HPC). Male KO exhibited more cognitive impairment and depressive-like behavior than female KO mice. In the mPFC, KO mice showed an overexpression of proinflammatory microglia, increased transcriptional levels of Dat, Drd1, and Drd2, exacerbated dopamine levels, and abnormal neural spiking and oscillatory activities in the mPFC and HPC. Chronic treatment with methylphenidate (MPH) (1 and 3 mg/kg) reversed the behavioral deficits, reduced proinflammatory microglia in the mPFC, normalized prefrontal Dat and Drd2 gene expression, and increased Bdnf and Nrf2 mRNA levels. These findings unravel the mechanisms underlying the beneficial effects of MPH on cognitive deficits and depressive-like behaviors observed in Mbnl2 KO mice, and suggest that MPH could be a potential candidate to treat the CNS deficiencies in DM1 patients.

Facilitation of dopamine-dependent long-term potentiation in the medial prefrontal cortex of male rats follows the behavioral effects of stress

The effect of stress on animal behavior and brain activity has been attracting growing attention in the last decades. Stress dramatically affects several aspects of animal behavior, including motivation and cognitive functioning, and has been used to model human pathologies such as post-traumatic stress disorder. A key question is whether stress alters the plastic potential of synaptic circuits. In this work, we evaluated if stress affects dopamine (DA)-dependent synaptic plasticity in the medial prefrontal cortex (mPFC). On male adolescent rats, we characterized anxiety- and depressive-like behaviors using behavioral testing before and after exposure to a mild stress (elevated platform, EP). After the behavioral protocols, we investigated DA-dependent long-term potentiation (DA-LTP) and depression (DA-LTD) on acute slices of mPFC and evaluated the activation of DA-producing brain regions by western and dot blot analysis. We show that exposure to the EP stress enhances DA-LTP and that desipramine (DMI) treatment abolishes this effect. We also found that DA-LTD is not affected by EP stress unless when this is followed by DMI treatment. In addition, EP stress reduces anxiety, an effect abolished by both DMI and ketamine, while motivation is promoted by previous exposure to EP stress independently of pharmacological treatments. Finally, this form of stress reduces the expression of the early gene cFOS in the ventral tegmental area. These findings support the idea that mild stressors can promote synaptic plasticity in PFC through a dopaminergic mechanism, an effect that might increase the sensitivity of mPFC to subsequent stressful experiences.

Developmental effects of environmental enrichment on selective and auditory sustained attention

Environmental enrichment (EE) has been used as a positive manipulation in different disease models. However, there is conflicting evidence reported in the literature about the effects of EE. Additionally, the time period that would be most beneficial in implementing environmental enrichment as an intervention is not clear. Our study aimed to systematically compare the prenatal, juvenile, mid-adolescence, and adulthood developmental trajectory to further the understanding of enriched environment's effects on selective and auditory sustained attention, corresponding to behavioral (conceived) and physiological-reflexive (non-conceived) measures. Rats were exposed for 21 days to enriched environment during various developmental periods and compared to age-matched controls. All groups were tested for long-term effects (at postnatal day 120 and onward) on selective and sustained attention. We found that the exposure to enriched environment during mid-adolescence has yielded the most significant and long-term pattern of effects, including selective and auditory sustained attention performance, increased foraging-like behavior and a significant decrease in corticosterone level. Similarly, the exposure to EE at juvenile period improved selective attention, increased foraging-like behavior, and reduced anxiety levels as reflected in the open field as well as in low corticosterone levels. These results specify a crucial period along the developmental trajectory for applying environmental enrichment. Mid-adolescence is suggested, in future basic and translational studies, as the sensitive time period that induces the most beneficial and long-term effects of EE on attention. The current findings suggest that the exposure to EE during mid-adolescence should be further considered and studied as behavioral alternative intervention, or as adjuvant behavioral therapy, aimed to decrease the probability to develop ADHD in post-adolescence period. This suggestion is highly relevant due to the debate regarding the pros and cons of screens usage (e.g. Facebook, online games, etc.) during early life that decreases environmental enrichment, especially, direct social interaction.

A Systematic Review of Interleukin-1β in Post-Traumatic Stress Disorder: Evidence from Human and Animal Studies

Pro-inflammatory cytokines, such as interleukin (IL)-1β, have been implicated as underlying pathophysiological mechanisms and potential biomarkers of post-traumatic stress disorder (PTSD). This systematic review examines data regarding IL-1β production/concentration in human and animal studies of PTSD. In accordance with PRISMA guidelines, relevant articles from PubMed were reviewed from inception until July 10, 2017. Nineteen studies were eligible for inclusion. Animal studies demonstrated increased hippocampal IL-1β in rodent models of PTSD. Several immunomodulatory drugs were shown to reduce elevated IL-1β levels and anxiety-like behaviors in animals. Human cross-sectional studies showed contradictory results; serum and plasma IL-1β concentrations in PTSD patients were either elevated or did not differ from control groups. In vitro IL-1β production by stimulated cells demonstrated no difference between PTSD and control participants, although spontaneous in vitro production of IL-1β was increased in the PTSD group. The findings from 2 longitudinal studies were inconsistent. Given the conflicting findings, it is premature to consider IL-1β as a biomarker of PTSD. Anti-inflammatory agents may reduce IL-1β, and be a potential basis for future therapeutic agents in PTSD treatment. More longitudinal research is needed to better understand the role of IL-1β in the development and/or maintenance of PTSD.

A probabilistic model of startle response reveals opposite effects of acute versus chronic Methylphenidate treatment

BACKGROUND

The startle response is considered as the major physio-behavioral indication of anxiety in health and disease conditions. However, due to different protocols of stimulation and measurement, the magnitude as well as the appearance of the startle response is inconsistent.

NEW METHOD

We postulate that the startle probability and not merely the amplitude may bare information that will form a consistent physiological measure of anxiety.

RESULTS

To examine the proof-of-concept of our suggested probability model, we evaluated the effects of acute (single) versus chronic (14 days) MPH administration on both startle amplitude and probability. We found that both acute and chronic MPH administration has yielded similar effects on startle amplitude. However, acute MPH increased the startle's probability while chronic MPH decreased it. Next, we evaluated the effects of acute versus chronic stress on the startle's parameters and found a complementary effect. Explicitly, acute stress increased the startle's probability while chronic stress increased the startle amplitude. In contrast, enriched environment had no significant effects. Finally, to further validate the probability measure, we show that Midazolam had significant anxiolytic effects. In the second part, we investigated the acoustic startle response parameters (e.g. background noise and pulse duration), to better understand the interplay between these parameters and the startle amplitude versus probability.

CONCLUSIONS

We show that the probabilistic element of the startle response does not only point to deeper physiologic relationships but may also serve as "hidden variables" congruent but not entirely identical to the commonly researched amplitude of the startle response.

Heritable Differences in Catecholamine Signaling Modulate Susceptibility to Trauma and Response to Methylphenidate Treatment: Relevance for PTSD

Alterations in cortical catecholamine signaling pathways can modulate acute and enduring responses to trauma. Heritable variation in catecholamine signaling is produced by a common functional polymorphism in the catechol-O-methyltransferase (COMT), with Val carriers exhibiting greater degradation of catecholamines than Met carriers. Furthermore, it has recently been suggested that drugs enhancing cortical catecholamine signaling may be a new therapeutic approach for posttraumatic stress disorder (PTSD) patients. We hypothesized that heritable differences in catecholamine signaling regulate the behavioral response to trauma, and that methylphenidate (MPD), a drug that preferentially blocks catecholamine reuptake in the prefrontal cortex (PFC), exerts COMT-dependent effects on trauma-induced behaviors. We first examined the contribution of the functional mutation COMTval158met to modulate enduring behavioral responses to predator stress in a unique "humanized" COMTval158met mouse line. Animals were exposed to a predator (cat) for 10 min and enduring avoidance behaviors were examined in the open field, light-dark box, and "trauma-reminder" tests 1-2 weeks later. Second, we examined the efficacy of chronic methylphenidate to reverse predator stress effects and if these effects were modulated by COMTval158met genotype. Mice were exposed to predator stress and began treatment with either saline or methylphenidate (3 mg/kg/day) 1 week after stress until the end of the testing [avoidance behaviors, working memory, and social preference (SP)]. In males, predator stress and COMTval158met had an additive effect on enduring anxiety-like behavior, with Val stressed mice showing the strongest avoidance behavior after stress compared to Met carriers. No effect of COMT genotype was observed in females. Therefore methylphenidate effects were investigated only in males. Chronic methylphenidate treatment reversed the stress-induced avoidance behavior and increased social investigation independently of genotype. Methylphenidate effects on working memory, however, were genotype-dependent, decreasing working memory in non-stressed Met carriers, and improving stress-induced working memory deficit in Val carriers. These results suggest that heritable variance in catecholamine signaling modulates the avoidance response to an acute trauma. This work supports recent human findings that methylphenidate might be a therapeutic alternative for PTSD patients and suggests that methylphenidate effects on anxiety (generalized avoidance, social withdrawal) vs. cognitive (working memory) symptoms may be modulated through COMT-independent and dependent mechanisms, respectively.

Dopamine D2/D3 receptor agonists attenuate PTSD-like symptoms in mice exposed to single prolonged stress

Medications that enhance dopaminergic neurotransmission can be useful in the pharmacotherapy of posttraumatic stress disorder (PTSD), which manifests as fearful memory retrieval, anxiety and depression. We examined the effects of subchronic (15 days) treatment with select dopaminergic medications, including bromocriptine, modafinil, dihydrexidine, rotigotine and pramipexole, in a mouse model of PTSD induced by single prolonged stress (mSPS). The potential antidepressant-like and anxiolytic effects of the medications were measured by the forced swim test (FST) and the elevated plus maze (EPM) test, respectively. In addition, we studied the effects of these medications on memory retrieval in an auditory fear conditioning (FC) test, on ultrasonic vocalizations (USVs) induced by restraint stress, and on spontaneous locomotor activity (SLA). We report that a single exposure to a severe and complex set of stressors several days before testing increased immobility time in the FST and freezing in the FC paradigm and reduced the time spent in the open arms of the EPM. The stressed mice also displayed increased USVs, especially the short type. While none of the tested dopamine-mimetics exhibited anxiolytic-like effects, rotigotine produced antidepressant-like activity specifically in the mSPS-exposed animals. Moreover, both rotigotine and pramipexole shortened the duration of freezing in the fear conditioning test, but only in the mSPS-exposed mice. This study supports the hypothesis that the activation of dopaminergic D2/D3 receptors may be a promising pharmacotherapy for PTSD.

Methylphenidate Dose-Dependently Affects Aggression and Improves Fear Extinction and Anxiety in BALB/cJ Mice

Overt aggression, increased anxiety, and dysfunctional fear processing are often observed in individuals with conduct disorder (CD) and attention-deficit hyperactivity disorder (ADHD). Methylphenidate (MPH), a psychostimulant increasing dopamine and noradrenaline tone, is effective in reducing aggression in both CD and ADHD individuals. However, it is unclear to which extent these effects of MPH are dose dependent. Here, the effects of acute intraperitoneal MPH (3 and 10 mg/kg) on aggression, anxiety, social behavior, and fear extinction were investigated in BALB/cJ mice. Previous studies in BALB/cJ mice have revealed high levels of aggression and anxiety that are associated with reduced top-down cortical control. Administration of 3 mg/kg MPH prolonged the attack latency and prevented escalation of aggression over time compared to vehicle-treated mice, while 10 mg/kg MPH increased number of bites and attacks. In addition, 3 mg/kg MPH decreased social interaction slightly. A strong anxiolytic effect was found after administration of both the 3 and 10 mg/kg doses in the elevated plus maze and the open-field test. In addition, while vehicle-treated BALB/cJ animals showed intact freezing, both doses of MPH decreased freezing to the unconditioned stimulus in a fear-conditioning paradigm. A long-lasting effect on fear extinction was visible after treatment with the 10 mg/kg dose. The data support a role for MPH in the regulation of anxiety, fear processing, and aggression in BALB/cJ mice, with the latter effect in a dose-dependent manner. The findings provide a further context for examining the effects of MPH in clinical disorders such as ADHD and CD.

Attention Deficit Hyperactivity Disorder and Risk of Posttraumatic Stress and Related Disorders: A Prospective Longitudinal Evaluation in U.S. Army Soldiers

Cross-sectional associations between attention deficit hyperactivity disorder (ADHD) and posttraumatic stress disorder (PTSD) have been observed, but longitudinal studies assessing this association are lacking. This prospective study evaluated the association between predeployment ADHD and postdeployment PTSD among U.S. Army soldiers. Soldiers who deployed to Afghanistan were surveyed before deployment (T0) and approximately 1 month (T1), 3 months (T2), and 9 months (T3) after their return. Logistic regression was performed to estimate the association between predeployment ADHD and postdeployment (T2 or T3) PTSD among 4,612 soldiers with data at all waves and no record of stimulant medication treatment during the study. To evaluate specificity of the ADHD-PTSD association, we examined associations among predeployment ADHD, postdeployment major depressive episode (MDE), generalized anxiety disorder (GAD), and suicidal ideation. Weighted prevalence of ADHD predeployment was 6.1% (SE = 0.4%). Adjusting for other risk factors, predeployment ADHD was associated with risk of postdeployment PTSD, adjusted odds ratio (AOR) = 2.13, 95% CI [1.51, 3.00], p < .001, including incidence among soldiers with no predeployment history of PTSD, AOR = 2.50, 95% CI [1.69, 3.69], p < .001. ADHD was associated with postdeployment MDE, AOR = 2.80, 95% CI [2.01, 3.91], p < .001, and GAD, AOR = 3.04, 95% CI [2.10, 4.42], p < .001, but not suicidal ideation. Recognition of associations between predeployment ADHD and postdeployment PTSD, MDE, and GAD may inform targeted prevention efforts. Future research should examine whether treatment of ADHD is protective against PTSD and related disorders in trauma-exposed individuals.

Imaging the Role of Inflammation in Mood and Anxiety-related Disorders

Background

Studies investigating the impact of a variety of inflammatory stimuli on the brain and behavior have reported evidence that inflammation and release of inflammatory cytokines affect circuitry relevant to both reward and threat sensitivity to contribute to behavioral change. Of relevance to mood and anxiety-related disorders, biomarkers of inflammation such as inflammatory cytokines and acute-phase proteins are reliably elevated in a significant proportion of patients with major depressive disorder (MDD), bipolar disorder, anxiety disorders and post-traumatic stress disorder (PTSD).

Methods

This review summarized clinical and translational work demonstrating the impact of peripheral inflammation on brain regions and neurotransmitter systems relevant to both reward and threat sensitivity, with a focus on neuroimaging studies involving administration of inflammatory stimuli. Recent translation of these findings to further understand the role of inflammation in mood and anxiety-related disorders is also discussed.

Results

Inflammation was consistently found to affect basal ganglia and cortical reward and motor circuits to drive reduced motivation and motor activity, as well as anxiety-related brain regions including amygdala, insula and anterior cingulate cortex, which may result from cytokine effects on monoamines and glutamate. Similar relationships between inflammation and altered neurocircuitry have been observed in MDD patients with increased peripheral inflammatory markers, and such work is on the horizon for anxiety disorders and PTSD.

Conclusion

Neuroimaging effects of inflammation on reward and threat circuitry may be used as biomarkers of inflammation for future development of novel therapeutic strategies to better treat mood and anxiety-related disorders in patients with high inflammation.

Acupuncture modulates stress response by the mTOR signaling pathway in a rat post-traumatic stress disorder model

Post-traumatic stress disorder (PTSD) is a psychiatric disease that can form following exposure to a traumatic event. Acupuncture has been proposed as a beneficial treatment for PTSD, but the underlying mechanisms remain unclear. The present study investigated whether acupuncture improves depression- and anxiety-like behaviors induced using a single prolonged stress (SPS) as a PTSD rat model. In addition, we investigated whether the effects were mediated by increased mTOR activity and its downstream signaling components, which contribute to protein synthesis required for synaptic plasticity in the hippocampus. We found that acupuncture at HT8 significantly alleviated both depression- and anxiety-like behaviors induced by SPS in rats, as assessed by the forced swimming, elevated plus maze, and open field tests; this alleviation was blocked by rapamycin. The effects of acupuncture were equivalent to those exerted by fluoxetine. Acupuncture regulated protein translation in the mTOR signaling pathway and enhanced the activation of synaptic proteins, PSD95, Syn1, and GluR1 in the hippocampus. These results suggest that acupuncture exerts antidepressant and anxiolytic effects on PTSD-related symptoms by increasing protein synthesis required for synaptic plasticity via the mTOR pathway in the hippocampus. Acupuncture may be a promising treatment for patients with PTSD and play a role as an alternative PTSD treatment.

Impact of developmental exposure to methylphenidate on rat brain's immune privilege and behavior: Control versus ADHD model

Attention deficit hyperactivity disorder (ADHD) is the most prevalent childhood mental disorders that often persists into adulthood. Moreover, methylphenidate (MPH) is the mainstay of medical treatment for this disorder. Yet, not much is known about the neurobiological impact of MPH on control versus ADHD conditions, which is crucial to simultaneously clarify the misuse/abuse versus therapeutic use of this psychostimulant. In the present study, we applied biochemical and behavioral approaches to broadly explore the early-life chronic exposure of two different doses of MPH (1.5 and 5 mg/kg/day) on control and ADHD rats (Wistar Kyoto and Spontaneously Hypertensive rats, respectively). We concluded that the higher dose of MPH promoted blood-brain barrier (BBB) permeability and elicited anxiety-like behavior in both control and ADHD animals. BBB dysfunction triggered by MPH was particularly prominent in control rats, which was characterized by a marked disruption of intercellular junctions, an increase of endothelial vesicles, and an upregulation of adhesion molecules concomitantly with the infiltration of peripheral immune cells into the prefrontal cortex. Moreover, both doses of MPH induced a robust neuroinflammatory and oxidative response in control rats. Curiously, in the ADHD model, the lower dose of MPH (1.5 mg/kg/day) had a beneficial effect since it balanced both immunity and behavior relative to vehicle animals. Overall, the contrasting effects of MPH observed between control and ADHD models support the importance of an appropriate MPH dose regimen for ADHD, and also suggest that MPH misuse negatively affects brain and behavior.

Mifepristone reduces hypothalamo-pituitary-adrenal axis activation and restores weight loss in rats subjected to dietary restriction and methylphenidate administration

This study evaluates the efficacy of mifepristone on weight restoration in rats subjected to dietary restriction and methylphenidate administration. 25 female rats aged between 9 and 12 months were divided into 2 groups: 5 controls (exposed only to dietary restriction) and 20 rats that were administered 5 mg/kg/d of methylphenidate before meal exposure, for 36 days. Among rats who responded to methylphenidate (weight loss of 15-25%) weeks after its administration, a group of 6 rats continued to receive only methylphenidate ("Met" group), and another group received 10 mg/kg/d of mifepristone in addition to methylphenidate for 18 days ("Met+Mif" group; n = 6). The mean weight of the "Met+Mif" group remained significantly lower when compared to the control group (87.63 ± 2.83% vs 96.29 ± 3.26%; p < 0.001 respectively) but was significantly higher than that of the "Met" group (87.63 ± 2.83% vs. 80.61 ± 3.52%; p < 0.001 respectively). Plasma concentrations of adiponectin and gene expression of its receptors in rats brain were significantly higher in the "Met" group as compared to the "Met+Mif" and control groups (p < 0.01). Accordingly, mifepristone reduces HPA axis activation and restores weight through adipose tissue recovering. It might be considered a promising treatment for anorexia nervosa patients in future studies.

Interaction between methylphenidate, methadone and different antidepressant drugs on antinociception in mice, and possible clinical implications

OBJECTIVES

Methylphenidate (MPH), a psychostimulant used for treatment of attention deficit hyperactivity disorder (ADHD), is widely used by patients on antidepressants and methadone maintenance treatment (MMT). Preclinical studies showed MPH to exert analgesic effects when given alone or with morphine.

METHODS

Using the hotplate assay on mice, we studied the interaction of acute doses of MPH with sub-threshold doses of methadone and different antidepressant medications and the interaction of increasing doses of MPH with chronic methadone.

RESULTS

Adding a sub-threshold dose of venlafaxine, desipramine or clomipramine to MPH produced significant augmentation of MPH antinociception with each medication (P < 0.05). No such interactions were found between escitalopram and acute methadone. However, addition of increasing doses of MPH to chronic methadone given for 2 weeks using ALZET osmotic mini pumps induced augmentation of the antinociceptive effect of chronic methadone exclusively at high dose of MPH (7.5 mg/kg).

CONCLUSIONS

These findings may implicate the need of an excessive attention to the administration of MPH to MMT patients. The no interaction found between MPH and escitalopram may hint to the possibly safe co-administration of MPH and selective serotonin reuptake inhibitors (SSRIs) to depressed ADHD patients. Further studies are needed in order to validate these possible clinical implications.

Immune signaling mechanisms of PTSD risk and symptom development: insights from animal models

Post-traumatic stress disorder (PTSD) is characterized by persistent re-experiencing of a traumatic event, avoidance, and increased arousal. The approved pharmacological treatments for PTSD have limited efficacy (~60% treatment response), supporting the need for identification of biomarkers and novel pharmacological therapies. Mounting evidence suggests increased inflammatory markers and altered immune gene expression correlate with the severity of symptoms in PTSD patients. However a causal role of immune signaling in development and maintenance of PTSD symptoms is not clear, as inflammation may also be an epiphenomenon related to metabolic and behavioral effects of stress. Animal studies have been critical in understanding the potential causal role of immune signaling in PTSD. In this review we will present the most recent evidence, primarily focusing on the last 3 years, for inflammatory dysfunction both preceding and following PTSD, and how animal models of PTSD have contributed to our understanding of immune mechanisms involved in enduring anxiety after trauma. We will particularly focus on the role of peripheral vs. central immune signaling, the differences between single vs. chronic stress models of PTSD and recent utilization of these models to investigate novel anti-inflammatory treatments. We also highlight some current gaps in the literature including models of TBI/PTSD comorbidity, lack of translational peripheral markers of inflammation and the relatively incomplete understanding of the inflammatory trajectory after severe stress.

Pre-trauma Methylphenidate in rats reduces PTSD-like reactions one month later

In basic research, the etiology of fear-related pathologies, such as post-traumatic stress disorder (PTSD), is conceptualized using fear-conditioning protocols that pair environmental stimuli (that is, a conditioned stimulus-CS) with an aversive, unconditioned stimulus (US) to elicit an assessable conditioned fear response. Although pathophysiological models agree that regulatory dysfunctions in this associative process may instigate fear-related pathology, current opinions differ in regard to the nature of these dysfunctions. Primarily derived from studies in rodents, the prevailing perspective proposes that pathological fear-reactions develop from intensified and overly consolidated CS-US associations. Alternatively, models derived from studies in humans suggest that tempospatial inaccuracies in representations of associative fear might precipitate pathology by engendering failure to differentiate present experiences and past memories of threat. To test this concept in rodents, we administered rats with cognition enhancing doses of Methylphenidate before or after fear conditioning and measured long-term alterations in their conditioned fear behaviors and PTSD-like reactions. The administration of Methylphenidate before fear-memory formation indeed reduced anxious-like responses during fear-memory retrieval one month later. An individual profiling analysis revealed that Methylphenidate onset had opposing effects on the risk for PTSD-like classification. The modulation of initial learning and formation of associative fear normalized the risk for developing PTSD-like reaction. In contrast, when the effects of Methylphenidate were exerted only over later consolidation this risk increased markedly. When examined under current psychiatric and neuropharmacologic literature, these results reveal a possible strategy of using low-dose Methylphenidate for the prevention of PTSD in high risk populations.

Randomized Placebo-Controlled Trial of Methylphenidate or Galantamine for Persistent Emotional and Cognitive Symptoms Associated with PTSD and/or Traumatic Brain Injury

We report findings from a 12-week randomized double-blinded placebo-controlled trial of methylphenidate or galantamine to treat emotional and cognitive complaints in individuals (n=32) with a history of PTSD, TBI, or both conditions. In this small pilot study, methylphenidate treatment was associated with clinically meaningful and statistically significant improvement compared with placebo on the primary outcome, a measure of cognitive complaints (Ruff Neurobehavioral Inventory-Postmorbid Cognitive Scale), as well as on the secondary outcomes reflecting post-concussive (Rivermead Post Concussive Symptom Questionnaire) and post-traumatic stress symptoms (Posttraumatic Stress Disorder Checklist). Treatment was well tolerated. These results suggest the need for a larger RCT to replicate and confirm these findings. Design considerations for such a trial should include the need for multiple sites to facilitate adequate recruitment and extension of the treatment and follow-up periods.

Quinazoline-based tricyclic compounds that regulate programmed cell death, induce neuronal differentiation, and are curative in animal models for excitotoxicity and hereditary brain disease

Expanding on a quinazoline scaffold, we developed tricyclic compounds with biological activity. These compounds bind to the 18 kDa translocator protein (TSPO) and protect U118MG (glioblastoma cell line of glial origin) cells from glutamate-induced cell death. Fascinating, they can induce neuronal differentiation of PC12 cells (cell line of pheochromocytoma origin with neuronal characteristics) known to display neuronal characteristics, including outgrowth of neurites, tubulin expression, and NeuN (antigen known as 'neuronal nuclei', also known as Rbfox3) expression. As part of the neurodifferentiation process, they can amplify cell death induced by glutamate. Interestingly, the compound 2-phenylquinazolin-4-yl dimethylcarbamate (MGV-1) can induce expansive neurite sprouting on its own and also in synergy with nerve growth factor and with glutamate. Glycine is not required, indicating that N-methyl-D-aspartate receptors are not involved in this activity. These diverse effects on cells of glial origin and on cells with neuronal characteristics induced in culture by this one compound, MGV-1, as reported in this article, mimic the diverse events that take place during embryonic development of the brain (maintenance of glial integrity, differentiation of progenitor cells to mature neurons, and weeding out of non-differentiating progenitor cells). Such mechanisms are also important for protective, curative, and restorative processes that occur during and after brain injury and brain disease. Indeed, we found in a rat model of systemic kainic acid injection that MGV-1 can prevent seizures, counteract the process of ongoing brain damage, including edema, and restore behavior defects to normal patterns. Furthermore, in the R6-2 (transgenic mouse model for Huntington disease; Strain name: B6CBA-Tg(HDexon1)62Gpb/3J) transgenic mouse model for Huntington disease, derivatives of MGV-1 can increase lifespan by >20% and reduce incidence of abnormal movements. Also in vitro, these derivatives were more effective than MGV-1.

The alanine-serine-cysteine-1 (Asc-1) transporter controls glycine levels in the brain and is required for glycinergic inhibitory transmission

Asc-1 (SLC7A10) is an amino acid transporter whose deletion causes neurological abnormalities and early postnatal death in mice. Using metabolomics and behavioral and electrophysiological methods, we demonstrate that Asc-1 knockout mice display a marked decrease in glycine levels in the brain and spinal cord along with impairment of glycinergic inhibitory transmission, and a hyperekplexia-like phenotype that is rescued by replenishing brain glycine. Asc-1 works as a glycine and L-serine transporter, and its transport activity is required for the subsequent conversion of L-serine into glycine in vivo. Asc-1 is a novel regulator of glycine metabolism and a candidate for hyperekplexia disorders.