Novel CHATogether family-centered mental health care in the post-pandemic era: a pilot case and evaluation.

BACKGROUND: The COVID-19 pandemic impacted children, adolescents, and their families, with significant psychosocial consequences. The prevalence of anxiety, depression, and self-injurious behaviors increased in our youth, as well as the number of suicide attempts and hospitalizations related to suicidal ideation. Additionally, parents' mental health saw increasing rates of depression, irritability, and alcohol use combined with worsening family function, child-parent connectedness, positive family expressiveness, and increases in family conflict. In light of these statistics, we created CHATogether (Compassionate Home, Action Together), a pilot family-centered intervention using multi-faceted psychotherapeutic approaches to improve familial communication and relational health between adolescents and their parents. This paper discusses the implementation of the CHATogether intervention at the Adolescent Intensive Outpatient Program (IOP), providing an example of the intervention through an in-depth pilot case, and evaluation of the program's acceptability and feasibility. METHODS: This paper describes a case in detail and evaluation from a total of 30 families that completed CHATogether in the initial pilot. Each family had 4-6 one-hour CHATogether sessions during their 6-week treatment course at the IOP. Before and after CHATogether, adolescents and their parents separately completed a questionnaire designed to explore their perceived family conflicts. After completion of the program, participants completed a brief quality improvement survey to assess their overall experience with CHATogether. In the reported case, the family completed Patient-Reported Outcomes Measurement Information System (PROMIS) depressive and anxiety symptoms scales, Conflict Behavior Questionnaires (CBQ), 9-item Concise Health Risk Tracking Self-Report (CHRT-SR9), and help-seeking attitude from adults during distress and suicide concerns. RESULTS: The pilot case showed a trend of improvement in reported depressive and anxiety symptoms, child-parent conflicts, subfactors of suicide risk including pessimism, helplessness, and despair, help-seeking acceptability from parents for suicide concerns, and the establishment of individualized family relationship goals. Preliminary feedback from participating families demonstrated positive effects on intra-family communication and improvement in the overall family dynamic. Adolescents (n = 30/30) and their parents (n = 30/30) rated "strongly agree" or "agree" that their families had benefited from CHATogether and welcomed participation in future program development. CONCLUSION: This study presents CHATogether as a novel family-centered intervention to address post-pandemic family mental health stress, especially when a family system was disrupted and negatively affected the mental health of children and adolescents. The intervention facilitated positive child-parent communication on a variety of topics, through tools such as emotional expression and help-seeking behavior. The reported pilot case and evaluation suggested CHATogether's acceptability and feasibility in a clinical context. We also provided quality improvement feedback to guide future studies in establishing the efficacy of CHATogether and other similar models of clinical family interventions.

Navigating Intersectional Identities: Clinical Considerations for Working With LGBTQ Asian American Youth.

LGBTQ Asian American youth face unique challenges related to their marginalized identities. It is well documented that Asian Americans who need mental health treatment access care at lower rates than White populations.1 Although Asian cultural values are often cited as reasons for decreased help-seeking behavior, research suggests structural barriers including cost, lack of culturally tailored services, and lack of knowledge of available resources as greater contributors to these disparities.1 Asian Americans have also been subject to the "model minority" myth, the stereotype that the community is universally high achieving, rule following, and well adjusted. This false narrative contributes to negative mental health outcomes driven by racial discrimination and homogenizing the Asian American experience. This masks the diversity in mental health needs among Asian Americans. In addition, LGBTQ Asian Americans experience microaggressions, the perception of being "not queer enough," and racism from LGBTQ spaces that often primarily cater to a White population.2.

CHATogether: a novel digital program to promote Asian American Pacific Islander mental health in response to the COVID-19 pandemic.

BACKGROUND: In response to the COVID-19 pandemic and the associated rise in anti-Asian hate crimes, we developed the Compassionate Home, Action Together program, (CHATogether) to support the mental health of the Asian American and Pacific Islander (AAPI) community. CHATogether is a culturally informed and virtually delivered support program that harnesses the talents of AAPI teens, young adults, parents, and mental health professionals who share a commitment to serve their local communities. METHODS: Our objective was to identify the active components, optimal utilization, potential benefits, and pertinent limitations of the CHATogether program during the 3 years since its inception in 2019. By that time, the program had developed six distinct component arms: interactive theater, mental health education, research, peer support and community outreach, collaboration, and AAPI mentorship. To work towards this objective, we conducted a qualitative study using thematic analysis and an inductive approach based on grounded theory (GT), in which we analyzed anonymized transcripts of four focus groups, comprised of 20 program participants (11 females; 9 males). RESULTS: We developed a model of two overarching domains, each with three underlying themes: I. Individual stressors: (1) Family conflict; (2) Cultural identity; and (3) Pandemic impact; and II. Collective stressors: (1) Stigma related to mental health and illness; (2) Pandemic uncertainty; and (3) Xenophobia and societal polarization. Strengths of the CHATogether program include its role as a conduit toward AAPI connectedness and pride as well as purpose in building community. Through support and mentorship, the program cultivates a unique platform that promotes healing and resiliency in response to pandemic stressors and beyond. CONCLUSIONS: CHATogether creates a safe space for the AAPI community. Through its methods of storytelling and encouraging creativity, CHATogether facilitates the discussion of challenging topics specific to the AAPI community. Given the national mental health crisis that is further being exacerbated by the COVID-19 pandemic, a digital prevention program such as CHATogether holds promise towards providing access to mental health resources and supporting early help-seeking behaviors for individuals in the AAPI community.

Molecular and Epigenetic Mechanisms for the Complex Effects of Stress on Synaptic Physiology and Cognitive Functions.

Evidence over the past decades has found that stress, particularly through the corticosterone stress hormones, produces complex changes in glutamatergic signaling in prefrontal cortex, which leads to the alteration of cognitive processes medicated by this brain region. Interestingly, the effects of stress on glutamatergic transmission appear to be "U-shaped," depending upon the duration and severity of the stressor. These biphasic effects of acute vs chronic stress represent the adaptive vs maladaptive responses to stressful stimuli. Animal studies suggest that the stress-induced modulation of excitatory synaptic transmission involves changes in presynaptic glutamate release, postsynaptic glutamate receptor membrane trafficking and degradation, spine structure and cytoskeleton network, and epigenetic control of gene expression. This review will discuss current findings on the key molecules involved in the stress-induced regulation of prefrontal cortex synaptic physiology and prefrontal cortex-mediated functions. Understanding the molecular and epigenetic mechanisms that underlie the complex effects of stress will help to develop novel strategies to cope with stress-related mental disorders.

Estrogen in prefrontal cortex blocks stress-induced cognitive impairments in female rats.

Animal and human studies have found that males and females show distinct stress responses. Recent studies suggest the contribution of estrogen in the brain to this sexual dimorphism. Repeated stress has been found to impair cognitive behaviors via suppressing glutamatergic transmission and glutamate receptor surface expression in pyramidal neurons of prefrontal cortex (PFC) in male rats. On the contrary, female rats exposed to the same stress paradigms show normal synaptic function and PFC-mediated cognition. The level of aromatase, the enzyme for the biosynthesis of estrogen, is significantly higher in the PFC of females than males. The stress-induced glutamatergic deficits and memory impairment are unmasked by blocking estrogen receptors or aromatase in females, suggesting a protective role of estrogen against the detrimental effects of repeated stress.

The role of ventral striatal cAMP signaling in stress-induced behaviors.

The cAMP and cAMP-dependent protein kinase A (PKA) signaling cascade is a ubiquitous pathway acting downstream of multiple neuromodulators. We found that the phosphorylation of phosphodiesterase-4 (PDE4) by cyclin-dependent protein kinase 5 (Cdk5) facilitated cAMP degradation and homeostasis of cAMP/PKA signaling. In mice, loss of Cdk5 throughout the forebrain elevated cAMP levels and increased PKA activity in striatal neurons, and altered behavioral responses to acute or chronic stressors. Ventral striatum- or D1 dopamine receptor-specific conditional knockout of Cdk5, or ventral striatum infusion of a small interfering peptide that selectively targeted the regulation of PDE4 by Cdk5, produced analogous effects on stress-induced behavioral responses. Together, our results demonstrate that altering cAMP signaling in medium spiny neurons of the ventral striatum can effectively modulate stress-induced behavioral states. We propose that targeting the Cdk5 regulation of PDE4 could be a new therapeutic approach for clinical conditions associated with stress, such as depression.

Predictors of suicide attempts in 3.322 patients with affective disorders and schizophrenia spectrum disorders.

This study explores risk factors for suicide attempts using the electronic health records of 3322 patients with either schizophrenia spectrum disorders or affective disorders who underwent a comprehensive psychiatric evaluation at the Emergency Department at the Long Island Jewish Medical Center or the Hillside Evaluation Center at The Zucker Hillside Hospital from August 3rd 2011 to July 5th 2012. Multivariate regression analyses showed, after adjusting for sex, that previous suicidal attempts and financial or relationship losses were significantly associated with a current suicidal attempt. Additionally, higher odds of having a suicidal attempt were also found in those subjects with a diagnosis of an affective disorder, compared to a schizophrenia spectrum diagnosis, and those patients in the children/adolescent group compared to those in the adult/elderly group. Our study results confirm and expand results from prior studies. Therefore, physicians should be alert for the presence of any or all of these factors upon evaluation of psychiatric patients, and if present, either psychiatric hospitalization or a close psychiatric follow up in collaboration with family and a therapist would be key in reducing the risk of potential suicidal behavior.

Synergistic regulation of glutamatergic transmission by serotonin and norepinephrine reuptake inhibitors in prefrontal cortical neurons.

The monoamine system in the prefrontal cortex has been implicated in various mental disorders and has been the major target of anxiolytics and antidepressants. Clinical studies show that serotonin and norepinephrine reuptake inhibitors (SNRIs) produce better therapeutic effects than single selective reuptake inhibitors, but the underlying mechanisms are largely unknown. Here, we found that low dose SNRIs, by acting on 5-HT(1A) and α2-adrenergic receptors, synergistically reduced AMPA receptor (AMPAR)-mediated excitatory postsynaptic currents and AMPAR surface expression in prefrontal cortex pyramidal neurons via a mechanism involving Rab5/dynamin-mediated endocytosis of AMPARs. The synergistic effect of SNRIs on AMPARs was blocked by inhibition of activator of G protein signaling 3, a G protein modulator that prevents reassociation of G(i) protein α subunit and prolongs the ßγ-mediated signaling pathway. Moreover, the depression of AMPAR-mediated excitatory postsynaptic currents by SNRIs required p38 kinase activity, which was increased by 5-HT(1A) and α2-adrenergic receptor co-activation in an activator of G protein signaling 3-dependent manner. These results have revealed a potential mechanism for the synergy between the serotonin and norepinephrine systems in the regulation of glutamatergic transmission in cortical neurons.

Memory enhancement by targeting Cdk5 regulation of NR2B.

Many psychiatric and neurological disorders are characterized by learning and memory deficits, for which cognitive enhancement is considered a valid treatment strategy. The N-methyl-D-aspartate receptor (NMDAR) is a prime target for the development of cognitive enhancers because of its fundamental role in learning and memory. In particular, the NMDAR subunit NR2B improves synaptic plasticity and memory when overexpressed in neurons. However, NR2B regulation is not well understood and no therapies potentiating NMDAR function have been developed. Here, we show that serine 1116 of NR2B is phosphorylated by cyclin-dependent kinase 5 (Cdk5). Cdk5-dependent NR2B phosphorylation is regulated by neuronal activity and controls the receptor's cell surface expression. Disrupting NR2B-Cdk5 interaction via a small interfering peptide (siP) increases NR2B surface levels, facilitates synaptic transmission, and improves memory formation in vivo. Our results reveal a regulatory mechanism critical to NR2B function that can be targeted for the development of cognitive enhancers.

Restoration of glutamatergic transmission by dopamine D4 receptors in stressed animals.

The prefrontal cortex (PFC), a key brain region for cognitive and emotional processes, is highly regulated by dopaminergic inputs. The dopamine D4 receptor, which is enriched in PFC, has been implicated in mental disorders, such as attention deficit-hyperactivity disorder and schizophrenia. Recently we have found homeostatic regulation of AMPA receptor-mediated synaptic transmission in PFC pyramidal neurons by the D4 receptor, providing a potential mechanism for D4 in stabilizing cortical excitability. Because stress is tightly linked to adaptive and maladaptive changes associated with mental health and disorders, we examined the synaptic actions of D4 in stressed rats. We found that neural excitability was elevated by acute stress and dampened by repeated stress. D4 activation produced a potent reduction of excitatory transmission in acutely stressed animals and a marked increase of excitatory transmission in repeatedly stressed animals. These effects of D4 targeted GluA2-lacking AMPA receptors and relied on the bi-directional regulation of calcium/calmodulin kinase II activity. The restoration of PFC glutamatergic transmission in stress conditions may enable D4 receptors to serve as a synaptic stabilizer in normal and pathological conditions.

Disrupted GABAAR trafficking and synaptic inhibition in a mouse model of Huntington's disease.

Growing evidence suggests that Huntington's disease (HD), a neurodegenerative movement disorder caused by the mutant huntingtin (htt) with an expanded polyglutamine (polyQ) repeat, is associated with the altered intracellular trafficking and synaptic function. GABA(A) receptors, the key determinant of the strength of synaptic inhibition, have been found to bind to the huntingtin associated protein 1 (HAP1). HAP1 serves as an adaptor linking GABA(A) receptors to the kinesin family motor protein 5 (KIF5), controlling the transport of GABA(A) receptors along microtubules in dendrites. In this study, we found that GABA(A)R-mediated synaptic transmission is significantly impaired in a transgenic mouse model of HD expressing polyQ-htt, which is accompanied by the diminished surface expression of GABA(A) receptors. Moreover, the GABA(A)R/HAP1/KIF5 complex is disrupted and dissociated from microtubules in the HD mouse model. These results suggest that GABA(A)R trafficking and function is impaired in HD, presumably due to the interference of KIF5-mediated microtubule-based transport of GABA(A) receptors. The diminished inhibitory synaptic efficacy could contribute to the loss of the excitatory/inhibitory balance, leading to increased neuronal excitotoxicity in HD.

Repeated stress causes cognitive impairment by suppressing glutamate receptor expression and function in prefrontal cortex.

Chronic stress could trigger maladaptive changes associated with stress-related mental disorders; however, the underlying mechanisms remain elusive. In this study, we found that exposing juvenile male rats to repeated stress significantly impaired the temporal order recognition memory, a cognitive process controlled by the prefrontal cortex (PFC). Concomitantly, significantly reduced AMPAR- and NMDAR-mediated synaptic transmission and glutamate receptor expression were found in PFC pyramidal neurons from repeatedly stressed animals. All these effects relied on activation of glucocorticoid receptors and the subsequent enhancement of ubiquitin/proteasome-mediated degradation of GluR1 and NR1 subunits, which was controlled by the E3 ubiquitin ligase Nedd4-1 and Fbx2, respectively. Inhibition of proteasomes or knockdown of Nedd4-1 and Fbx2 in PFC prevented the loss of glutamatergic responses and recognition memory in stressed animals. Our results suggest that repeated stress dampens PFC glutamatergic transmission by facilitating glutamate receptor turnover, which causes the detrimental effect on PFC-dependent cognitive processes.

Parkin controls dopamine utilization in human midbrain dopaminergic neurons derived from induced pluripotent stem cells.

Parkinson's disease (PD) is defined by the degeneration of nigral dopaminergic (DA) neurons and can be caused by monogenic mutations of genes such as parkin. The lack of phenotype in parkin knockout mice suggests that human nigral DA neurons have unique vulnerabilities. Here we generate induced pluripotent stem cells from normal subjects and PD patients with parkin mutations. We demonstrate that loss of parkin in human midbrain DA neurons greatly increases the transcription of monoamine oxidases and oxidative stress, significantly reduces DA uptake and increases spontaneous DA release. Lentiviral expression of parkin, but not its PD-linked mutant, rescues these phenotypes. The results suggest that parkin controls dopamine utilization in human midbrain DA neurons by enhancing the precision of DA neurotransmission and suppressing dopamine oxidation. Thus, the study provides novel targets and a physiologically relevant screening platform for disease-modifying therapies of PD.

The novel antipsychotic drug lurasidone enhances N-methyl-D-aspartate receptor-mediated synaptic responses.

N-Methyl-D-aspartate (NMDA) receptor (NMDAR) hypofunction has been postulated to contribute to the cognitive deficit of schizophrenia. In this study, we examined the effect of lurasidone (Latuda; Dainippon Sumitomo Pharma Co. Ltd., Tokyo, Japan), a newly approved atypical antipsychotic drug (APD), on NMDAR synaptic function in rat frontal cortical pyramidal neurons. In vivo administration of lurasidone produced a significant and selective enhancement of NMDAR-mediated synaptic responses and surface expression of NR2A and NR2B subunits. Lurasidone has high affinity for serotonin 5-HT(1A), 5-HT(2A), and 5-HT(7) receptors and dopamine D(2) receptors. In vivo administration of the 5-HT(7) receptor antagonist (2R)-1-[(3-hydroxyphenyl)sulfonyl]-2 -(2-(4-methyl-1-piperidinyl)ethyl)pyrrolidine (SB-269970) mimicked the enhancing effect of lurasidone on NMDAR responses, whereas the D(2) receptor antagonist haloperidol failed to do so. Previous studies have found that short-term administration of lurasidone reverses the cognitive impairment induced by subchronic administration of phencyclidine (PCP), an NMDAR noncompetitive antagonist. In this study, we found that lurasidone, as well as the prototypical atypical APD clozapine, restored NMDAR-mediated synaptic responses to normal levels in the PCP model of schizophrenia. These results suggest that NMDAR is the potential key molecular target of lurasidone, possibility via antagonizing 5-HT(7) receptors, which is consistent with evidence that 5-HT(7) receptor antagonism contributes to cognitive enhancement by atypical APDs in patients with schizophrenia.

Impaired alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor trafficking and function by mutant huntingtin.

Emerging evidence from studies of Huntington disease (HD) pathophysiology suggests that huntingtin (htt) and its associated protein HAP1 participate in intracellular trafficking and synaptic function. However, it is largely unknown whether AMPA receptor trafficking, which is crucial for controlling the efficacy of synaptic excitation, is affected by the mutant huntingtin with polyglutamine expansion (polyQ-htt). In this study, we found that expressing polyQ-htt in neuronal cultures significantly decreased the amplitude and frequency of AMPAR-mediated miniature excitatory postsynaptic current (mEPSC), while expressing wild-type huntingtin (WT-htt) increased mEPSC. AMPAR-mediated synaptic transmission was also impaired in a transgenic mouse model of HD expressing polyQ-htt. The effect of polyQ-htt on mEPSC was mimicked by knockdown of HAP1 and occluded by the dominant negative HAP1. Moreover, we found that huntingtin affected mESPC via a mechanism depending on the kinesin motor protein, KIF5, which controls the transport of GluR2-containing AMPARs along microtubules in dendrites. The GluR2/KIF5/HAP1 complex was disrupted and dissociated from microtubules in the HD mouse model. Together, these data suggest that AMPAR trafficking and function is impaired by mutant huntingtin, presumably due to the interference of KIF5-mediated microtubule-based transport of AMPA receptors. The diminished strength of glutamatergic transmission could contribute to the deficits in movement control and cognitive processes in HD conditions.

Amyloid beta peptide-(1-42) induces internalization and degradation of beta2 adrenergic receptors in prefrontal cortical neurons.

Emerging evidence indicates that amyloid ß peptide (Aß) initially induces subtle alterations in synaptic function in Alzheimer disease. We have recently shown that Aß binds to ß(2) adrenergic receptor (ß(2)AR) and activates protein kinase A (PKA) signaling for glutamatergic regulation of synaptic activities. Here we show that in the cerebrums of mice expressing human familial mutant presenilin 1 and amyloid precursor protein genes, the levels of ß(2)AR are drastically reduced. Moreover, Aß induces internalization of transfected human ß(2)AR in fibroblasts and endogenous ß(2)AR in primary prefrontal cortical neurons. In fibroblasts, Aß treatment also induces transportation of ß(2)AR into lysosome, and prolonged Aß treatment causes ß(2)AR degradation. The Aß-induced ß(2)AR internalization requires the N terminus of the receptor containing the peptide binding sites and phosphorylation of ß(2)AR by G protein-coupled receptor kinase, not by PKA. However, the G protein-coupled receptor kinase phosphorylation of ß(2)AR and the receptor internalization are much slower than that induced by ßAR agonist isoproterenol. The Aß-induced ß(2)AR internalization is also dependent on adaptor protein arrestin 3 and GTPase dynamin, but not arrestin 2. Functionally, pretreatment of primary prefrontal cortical neurons with Aß induces desensitization of ß(2)AR, which leads to attenuated response to subsequent stimulation with isoproterenol, including decreased cAMP levels, PKA activities, PKA phosphorylation of serine 845 on α-amino-2,3-dihydro-5-methyl-3-oxo-4-isoxazolepropanoic acid (AMPA) receptor subunit 1 (GluR1), and AMPA receptor-mediated miniature excitatory postsynaptic currents. This study indicates that Aß induces ß(2)AR internalization and degradation leading to impairment of adrenergic and glutamatergic activities.

Cellular mechanisms for dopamine D4 receptor-induced homeostatic regulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors.

Aberrant dopamine D(4) receptor function has been implicated in mental illnesses, including schizophrenia and attention deficit-hyperactivity disorder. Recently we have found that D(4) receptor exerts an activity-dependent bi-directional regulation of AMPA receptor (AMPAR)-mediated synaptic currents in pyramidal neurons of prefrontal cortex (PFC) via the dual control of calcium/calmodulin kinase II (CaMKII) activity. In this study, we examined the signaling mechanisms downstream of CaMKII that govern the complex effects of D(4) on glutamatergic transmission. We found that in PFC neurons at high activity state, D(4) suppresses AMPAR responses by disrupting the kinesin motor-based transport of GluR2 along microtubules, which was accompanied by the D(4) reduction of microtubule stability via a mechanism dependent on CaMKII inhibition. On the other hand, in PFC neurons at the low activity state, D(4) potentiates AMPAR responses by facilitating synaptic targeting of GluR1 through the scaffold protein SAP97 via a mechanism dependent on CaMKII stimulation. Taken together, these results have identified distinct signaling mechanisms underlying the homeostatic regulation of glutamatergic transmission by D(4) receptors, which may be important for cognitive and emotional processes in which dopamine is involved.

Homeostatic regulation of glutamatergic transmission by dopamine D4 receptors.

Alterations of synaptic transmission have been considered a core feature of mental disorders; thus, we examined the role of dopamine D(4) receptors, which is highly implicated in attention-deficit hyperactivity disorder and schizophrenia, in regulating synaptic functions of prefrontal cortex, a brain region critical for cognitive and emotional processes. We found that D(4) stimulation caused a profound depression or potentiation of AMPA receptor-mediated excitatory synaptic transmission in prefrontal cortex pyramidal neurons when their activity was elevated or dampened, respectively, which was accompanied by a D(4)-induced decrease or increase of AMPARs at synapses. The dual effects of D(4) on AMPAR trafficking and function was dependent on the D(4)-mediated bidirectional regulation of CaMKII activity via coupling to distinct signaling pathways, which provides a unique mechanism for D(4) receptors to serve as a homeostatic synaptic factor to stabilize cortical excitability.

Regulation of AMPA receptor channels and synaptic plasticity by cofilin phosphatase Slingshot in cortical neurons.

Cofilin, the major actin depolymerizing factor, modulates actin dynamics that contribute to spine morphology, synaptic transmission and plasticity. Much evidence implicates the cofilin inactivation kinase LIMK in synaptic function, but little is known about the cofilin activation phosphatase Slingshot in this regard. In this study, we found that suppressing endogenous Slingshot with small RNA interference or function-blocking antibody led to a dramatic reduction of AMPA receptor-mediated excitatory postsynaptic currents (EPSCs) in cortical neurons. Perturbation of Slingshot function also diminished the ability to express synaptic plasticity. Inactivating cofilin or disturbing actin dynamics reduced AMPAR-EPSCs in a Slingshot-dependent manner. Moreover, surface GluR 1 and synaptic GluR2/3 clusters were reduced by Slingshot knockdown. Our data suggest that Slingshot plays a pivotal role in AMPAR trafficking and synaptic transmission by controlling actin cytoskeleton via cofilin activation.

Delivery of GABAARs to synapses is mediated by HAP1-KIF5 and disrupted by mutant huntingtin.

The density of GABA(A) receptors (GABA(A)Rs) at synapses regulates brain excitability, and altered inhibition may contribute to Huntington's disease, which is caused by a polyglutamine repeat in the protein huntingtin. However, the machinery that delivers GABA(A)Rs to synapses is unknown. We demonstrate that GABA(A)Rs are trafficked to synapses by the kinesin family motor protein 5 (KIF5). We identify the adaptor linking the receptors to KIF5 as the huntingtin-associated protein 1 (HAP1). Disrupting the HAP1-KIF5 complex decreases synaptic GABA(A)R number and reduces the amplitude of inhibitory postsynaptic currents. When huntingtin is mutated, as in Huntington's disease, GABA(A)R transport and inhibitory synaptic currents are reduced. Thus, HAP1-KIF5-dependent GABA(A)R trafficking is a fundamental mechanism controlling the strength of synaptic inhibition in the brain. Its disruption by mutant huntingtin may explain some of the defects in brain information processing occurring in Huntington's disease and provides a molecular target for therapeutic approaches.