Phencyclidine

Anti-N-Methyl-D-Aspartate Receptor Encephalitis: Neuropsychiatric and Multidisciplinary Approach to a Patient Not Responding to First-Line Treatment

The understanding of anti-NMDA (N-methyl-D-aspartate) receptor encephalitis, recognized by Dalmau and colleagues in 2007, has come a long way in helping clinicians to recognize the significance of rapidly progressive psychiatric symptoms in patients who are actually suffering from autoimmune disease. This subtype of autoimmune encephalitis manifests from antibodies that target the NR1 and/or NR2 subunits of NMDA receptors in serum or cerebrospinal fluid. Since gaining notoriety among neurologists, it has shown an etiologic predilection for children, adolescents, and young adult females, often associated with ovarian teratomas. Conversely, it affects young males as well, though it is rarer to find co-occurring tumors. It is a multistage disorder, initially presenting with psychiatric symptoms that progress in varying fashion, including headache, fever, nuchal rigidity, emesis, seizure, autonomic instability, auditory and visual hallucinations, delusional ideation, agitation, altered sensorium, and motor disturbances (i.e. dyskinesia, catatonia, etc.). Early diagnosis is critical due to the relatively high (25%) mortality rate. In this case, we present the case of a 30-year-old male who presented to our institution’s Comprehensive Psychiatric Emergency Program (CPEP) exhibiting bizarre behavior and visual hallucinations, and was later confirmed to have anti-NMDA receptor encephalitis. The case report highlights the risk factors, disease course, and treatment modalities of anti-NMDA receptor encephalitis with special emphasis on the subsect of patients who may not respond to first-line therapies.

Drug-induced Hyperthermic Syndromes in Psychiatry

Hyperthermia, or extreme elevations in body temperature, can be life-threatening and may be caused by prescription drugs or illegal substances acting at a number of different levels of the neuraxis. Several psychotropic drug classes and combinations have been associated with a classic clinical syndrome of hyperthermia, skeletal muscle hypermetabolism, rigidity or rhabdomyolysis, autonomic dysfunction and altered mental status ranging from catatonic stupor to coma. It is critical for clinicians to have a high index of suspicion for these relatively uncommon drug-induced adverse effects and to become familiar with their management to prevent serious morbidity and mortality. Although these syndromes look alike, they are triggered by quite different mechanisms, and apart from the need to withdraw or restore potential triggering drugs and provide intensive medical care, specific treatments may vary. Clinical similarities have led to theoretical speculations about common mechanisms and shared genetic predispositions underlying these syndromes, suggesting that there may be a common “thermic stress syndrome” triggered in humans and animal models by a variety of pharmacological or environmental challenges.

Finding the Cause of Psychosis: A Challenging Case of Anti-NMDAR Encephalitis

An autoimmune response causing inflammation in the brain tissue is called autoimmune encephalitis. Autoantibodies directed against N-methyl-D-aspartate (NMDA) receptors cause a type of autoimmune encephalitis resulting in memory loss, confusion, and psychosis. A 28-year-old male with a history of schizophrenia, seizure disorder, and stroke presented with a 2-day history of bizarre behavior, restlessness, insomnia, agitation, and hallucinations. He was initially managed for acute psychosis without any improvement. Further workup for organic causes revealed positive NMDAR antibodies in both the cerebrospinal fluid and serum, confirming a diagnosis of autoimmune encephalitis. His condition later improved with steroids and intravenous immunoglobulins. This case signifies the importance of ruling out organic causes in patients with unexplained neuropsychiatric symptoms. NMDA encephalitis is more common in young females with underlying malignancies, especially ovarian teratomas. This case is unique, given the extremely rare occurrence of NMDA encephalitis in male patients without any malignancies.

Linking phencyclidine intoxication to the tryptophan-kynurenine pathway: Therapeutic implications for schizophrenia

Phencyclidine (PCP) is a dissociative anesthetic that induces psychotic symptoms and neurocognitive deficits in rodents similar to those observed in schizophrenia patients. PCP administration in healthy human subjects induces schizophrenia-like symptoms such as positive and negative symptoms, and a range of cognitive deficits. It has been reported that PCP, ketamine, and related drugs such as N-methyl-D-aspartate-type (NMDA) glutamate receptor antagonists, induce behavioral effects by blocking neurotransmission at NMDA receptors. Further, NMDA receptor antagonists reproduce specific aspects of the symptoms of schizophrenia. Neurochemical models based on the actions of PCP are well established, with increased focus on glutamatergic dysfunction as a basis for both symptoms and cognitive dysfunction in schizophrenia. On the other hand, the endogenous NMDA receptor antagonist, kynurenic acid (KYNA), which is a product of tryptophan-kynurenine pathway (KP) metabolism, is involved in schizophrenia pathogenesis. KYNA concentrations are elevated in the prefrontal cortex and cerebrospinal fluid of patients with schizophrenia. KYNA elevation affects neurotransmitter release in a similar manner to that of psychotomimetic agents such as PCP, underscoring a molecular basis of its involvement in schizophrenia pathophysiology. This review will highlight the relationship between PCP and KP metabolites based on evidence that both exogenous and endogenous NMDA receptor antagonists are involved in the pathogenesis of schizophrenia, and discuss our current understanding of the mechanisms underlying dysfunctional glutamatergic signaling as potential therapeutic targets for schizophrenia.

Catatonia in children and adolescents: New perspectives

INTRODUCTION

Catatonia is a rare and severe psychomotor condition in children and adolescents. In the current report, we aimed to review the recent literature.

METHOD

Using a PRISMA approach, we searched MEDLINE between 1982 and 2017 using the keywords 'CATATONIA' and 'CHILD' or 'ADOLESCENT'. In total, we reviewed 130 reports (controlled study, N=4; clinical chart, N=23; case report, N=54; and editorial/review, N=42).

RESULTS

Several aspects seem to be age specific: (1) although the clinical presentation resembles that in adults, some symptoms are important in children and adolescents (e.g., psychomotor regression). (2) Associated disorders are similar to that found in adults; however, schizophrenia is more frequently observed than mood disorder. Additionally, a history of neurodevelopmental disorders maybe encountered. (3) Morbidity and mortality are among the worst in child psychiatry. (4) Underlying organic conditions are highly prevalent (>20% of the cases), and their search is warranted because some diagnoses may result in specific treatments (e.g., immune-suppressor therapy for autoimmune conditions). (5) Symptomatic approaches - high dose of benzodiazepines and electroconvulsive therapy (ECT) - are as efficient in children or adolescents as they are in adults, but this finding needs to be acknowledged because a resistance against the use of ECT or high-dose medication exists among child psychiatrists.

DISCUSSION

Recent advances in child and adolescent catatonia research have offered major improvements in understanding catatonia and in new therapeutic opportunities. The syndrome is rare, but these advances need to be acknowledged in order to direct patients to centers that have developed a specific expertise.

The Differential Diagnosis and Treatment of Catatonia in Children and Adolescents

LEARNING OBJECTIVES

After participating in this activity, learners should be better able to:• Assess the etiologies associated with catatonia in children and adolescents• Evaluate the differential diagnosis of pediatric catatonia• Interpret the literature regarding the treatment of children and adolescents with catatonia OBJECTIVE: Pediatric catatonia is associated with many medical and psychiatric conditions. Mortality is high, and proper treatment can be lifesaving. Catatonia is increasingly recognized in pediatric populations, in which about 20% of cases are related to underlying medical conditions. To minimize morbidity, clinicians must rule out underlying disorders while simultaneously managing symptoms and causes. In our review we discuss (1) recommendations to aid rapid decision making, both diagnostic and therapeutic, (2) emergent conditions and management, (3) disorders associated with pediatric catatonia, including developmental, acquired, idiopathic, and iatrogenic etiologies, (4) available treatments, and (5) medicolegal considerations.

METHODS

Initial PubMed search without date constraints using MeSH terms related to pediatric catatonia, with subsequent searches on pertinent subtopics using PubMed and Google Scholar.

RESULTS

Pediatric catatonia is a dangerous but treatable neuropsychiatric condition. Psychiatrists need to be aware of differential diagnoses and to be able determine appropriate treatment within a short time frame. With prompt diagnosis and treatment, outcomes can be optimized.

CONCLUSION

Pediatric catatonia is underdiagnosed and requires rapid evaluation and management.

Autoimmune encephalitis: a potentially treatable cause of mental disorder

Autoimmune encephalitides can present with altered mental states, particularly psychosis and delirium. Psychiatrists need to be particularly vigilant in cases of first-episode psychosis and to look out for other, sometimes subtle, features of encephalitis. Encephalitis related to N-methyl-d-aspartate (NMDA) receptor autoantibodies is the most common autoimmune cause of isolated psychosis, the second being related to voltage-gated potassium channel (VGKC)-complex antibodies. Psychiatrists should note ‘red flag’ signs of seizures, autonomic instability, movement disorders and sensitivity to antipsychotic medication (including neuroleptic malignant syndrome). They should also be aware that, in some cases, encephalitis is a non-metastatic manifestation of malignancy. Treatment primarily involves suppression of immunity and is often successful if delivered early. There is accumulating evidence that isolated psychiatric syndromes can be caused by autoimmunity and this could potentially signal a significant change in the approach to disorders such as schizophrenia. Psychiatrists and neurologists need to work together to diagnose, manage and understand this group of conditions.

LEARNING OBJECTIVES

•

Case report of anti-N-methyl-D-aspartate receptor encephalitis in a middle-aged woman with a long history of major depressive disorder

BACKGROUND

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune disease involving antibodies against the NR1 subunits of NMDARs. The disease shows variable clinical presentation, and involves new-onset acute psychotic symptoms, making it difficult to differentiate from major depressive disorder with psychotic symptoms. Potential associations between this autoimmune disorder and onset or progression of major depressive disorder remains unclear.

CASE PRESENTATION

We present a rare case of a patient who had both major depressive disorder and anti-NMDAR encephalitis and in whom the encephalitis initially went undetected. The patient had been suffering from depressive disorder for more than 6 years without any treatment, when she was hospitalized for new-onset psychotic symptoms. She was initially diagnosed only with major depressive disorder with psychotic symptoms, but antipsychotics did not alleviate symptoms and the patient's psychiatric course began to fluctuate rapidly. Anti-NR1 IgG autoantibodies were detected in cerebrospinal fluid, and the combination of immunotherapy and antipsychotics proved more effective than antipsychotics alone. The patient was then also diagnosed with anti-NMDAR encephalitis.

CONCLUSIONS

Our case suggests that clinicians should consider anti-NMDAR encephalitis when a patient with depressive disorder shows sudden fluctuations in psychiatric symptoms. It also highlights the need for research into possible relationships between anti-NMDAR encephalitis and major depressive disorder.

Anti-N-methyl-d-aspartate receptor encephalitis: review of clinical presentation, diagnosis and treatment

Anti-N-methyl-d-aspartate (NMDA) receptor encephalitis is a form of encephalitis occurring primarily in women and associated with antibodies against NR1 or NR2 subunits of the NMDA receptor. As a potentially treatable differential for symptoms and signs seen in neurology and psychiatric clinics, clinicians practising across the lifespan should be aware of this form of encephalitis. Common clinical features include auditory and visual hallucinations, delusions, behavioural change (frequently with agitation), impaired consciousness, motor disturbance (ranging from dyskinesia to catatonia), seizures, and autonomic dysfunction. We present a review of the literature on the disorder, including its clinical presentation, differential diagnosis, epidemiology, treatment and prognosis.

Glutamatergic autoencephalitides: an emerging field

Autoimmune responses targeting synaptic proteins are associated with a wide range of neurologic symptoms. Among these disorders are those associated with antibodies to ionotropic glutamate receptors, including the NMDAR (N-methyl-D-aspartate receptor) and AMPAR (α-amino-3-hydrozy-5-methyl-4-isoxazolepropionic acid receptor). Patients with anti-NMDAR encephalitis present with psychiatric symptoms, seizures, movement disorders, impaired consciousness, and autonomic derangements; half of patients have an associated ovarian teratoma, and most patients respond to immunosuppressive therapies. Patients' antibodies bind to the amino terminal domain of the NMDAR, and result in loss of NMDARs from synapses with subsequent NMDAR hypofunction. Anti-NMDAR antibodies have now been reported in other neuropsychiatric conditions, including psychosis, dementia, and HSV encephalitis. The pathophysiologic relevance of anti-NMDAR antibodies in these disorders is not yet clear, but their presence may indicate a role for immunotherapy in some patients. Although considerable work remains to be done, our understanding of disorders associated with anti-glutamate receptor antibodies has grown exponentially since they were first described just over 7 years ago, revolutionizing neurology. These antibodies, by interfering with synaptic function, readily link basic science and clinical medicine, and have revealed the impact of sudden but sustained loss of specific neurotransmitter receptors in humans. Improved understanding of their pathophysiology will lead to better treatments for these diseases while providing novel insights regarding the roles of glutamate receptors in learning, memory, and neuropsychiatric disease.

NMDA receptor function, memory, and brain aging

An increasing level of N-methyl-D-aspartate (NMDA) receptor hypofunction within the brain is associated with memory and learning impairments, with psychosis, and ultimately with excitotoxic brain injury. As the brain ages, the NMDA receptor system becomes progressively hypofunctional, contributing to decreases in memory and learning performance. In those individuals destined to develop Alzheimer's disease, other abnormalities (eg, amyloidopathy and oxidative stress) interact to increase the NMDA receptor hypofunction (NRHypo) burden. In these vulnerable individuals, the brain then enters into a severe and persistent NRHypo state, which can lead to widespread neurodegeneration with accompanying mental symptoms and further cognitive deterioration. If the hypotheses described herein prove correct, treatment implications may be considerable. Pharmacological methods for preventing the overstimulation of vulnerable corticolimbic pyramidal neurons developed in an animal model may be applicable to the prevention and treatment of Alzheimer's disease.

Predicting risk and the emergence of schizophrenia

This article gives an overview of genetic and environmental risk factors for schizophrenia. The presence of certain molecular, biological, and psychosocial factors at certain points in the life span, has been linked to later development of schizophrenia. All need to be considered in the context of schizophrenia as a lifelong brain disorder. Research interest in schizophrenia is shifting to late childhood/early adolescence for screening and preventative measures. This article discusses those environmental risk factors for schizophrenia for which there is the largest evidence base.

Anti-NMDA receptor encephalitis: an important differential diagnosis in psychosis

We present four cases of confirmed anti-NMDA receptor encephalitis; three presented initially with serious psychiatric symptoms and the other developed significant psychiatric symptoms during the initial phase of illness. Brain biopsy findings of one patient are also described. Psychiatrists should consider anti-NMDA receptor encephalitis in patients presenting with psychosis and additional features of dyskinesias, seizures and catatonia, particularly where there is no previous history of psychiatric disorder.

Changes in gene expression after phencyclidine administration in developing rats: a potential animal model for schizophrenia

Repeated administration of phencyclidine (PCP), an N-methyl-d-aspartate (NMDA) receptor antagonist, during development, may result in neuronal damage that leads to behavioral deficits in adulthood. The present study examined the potential neurotoxic effects of PCP exposure (10mg/kg) in rats on postnatal days (PNDs) 7, 9 and 11 and the possible underlying mechanism(s) for neurotoxicity. Brain tissue was harvested for RNA extraction and morphological assessments. RNA was collected from the frontal cortex for DNA microarray analysis and quantitative RT-PCR. Gene expression profiling was determined using Illumina Rat Ref-12 Expression BeadChips containing 22,226 probes. Based on criteria of a fold-change greater than 1.4 and a P-value less than 0.05, 19 genes including NMDAR1 (N-methyl-d-aspartate receptor) and four pro-apoptotic genes were up-regulated, and 25 genes including four anti-apoptotic genes were down-regulated, in the PCP-treated group. In addition, the schizophrenia-relevant genes, Bdnf (Brain-derived neurotrophic factor) and Bhlhb2 (basic helix-loop-helix domain containing, class B, 2), were significantly different between the PCP and the control groups. Quantitative RT-PCR confirmed the microarray results. Elevated neuronal cell death was further confirmed using Fluoro-Jade C staining. These findings support the hypothesis that neurodegeneration caused by PCP occurs, at least in part, through the up-regulation of NMDA receptors, which makes neurons possessing these receptors more vulnerable to endogenous glutamate. The changes in schizophrenia-relevant genes after repeated PCP exposure during development may provide important information concerning the validation of an animal model for this disorder.

Adolescent brain maturation, the endogenous cannabinoid system and the neurobiology of cannabis-induced schizophrenia

Cannabis use during adolescence increases the risk of developing psychotic disorders later in life. However, the neurobiological processes underlying this relationship are unknown. This review reports the results of a literature search comprising various neurobiological disciplines, ultimately converging into a model that might explain the neurobiology of cannabis-induced schizophrenia. The article briefly reviews current insights into brain development during adolescence. In particular, the role of the excitatory neurotransmitter glutamate in experience-dependent maturation of specific cortical circuitries is examined. The review also covers recent hypotheses regarding disturbances in strengthening and pruning of synaptic connections in the prefrontal cortex, and the link with latent psychotic disorders. In the present model, cannabis-induced schizophrenia is considered to be a distortion of normal late postnatal brain maturation. Distortion of glutamatergic transmission during critical periods may disturb prefrontal neurocircuitry in specific brain areas. Our model postulates that adolescent exposure to Δ9-tetrahydrocannabinol (THC), the primary psychoactive substance in cannabis, transiently disturbs physiological control of the endogenous cannabinoid system over glutamate and GABA release. As a result, THC may adversely affect adolescent experience-dependent maturation of neural circuitries within prefrontal cortical areas. Depending on dose, exact time window and duration of exposure, this may ultimately lead to the development of psychosis or schizophrenia. The proposed model provides testable hypotheses which can be addressed in future studies, including animal experiments, reanalysis of existing epidemiological data, and prospective epidemiological studies in which the role of the dose-time-effect relationship should be central.

Drugs of abuse: management of intoxication and antidotes

Illicit drug intoxications are an increasing public health problem for which, in most cases, no antidotes are clinically available. The diagnosis and treatment of these intoxications requires a trained clinician with experience in recognizing the specific signs and symptoms of intoxications to individual drugs as well as polydrug intoxications, which are more the rule than the exception. To make the diagnosis, the clinical observation and a urine toxicology test are often enough. Evaluating the blood levels of drugs is frequently not practical because the tests can be expensive and results may be delayed and unavailable to guide the establishment of a treatment plan. Other laboratory tests may be useful depending on the drug or drugs ingested and the presence of other medical complications. The treatment should be provided in a quiet, safe and reassuring environment. Vital signs should be closely monitored. Changes in blood pressure, respiratory frequency and temperature should be promptly treated, particularly respiratory depression (in cases of opiate intoxication) or hyperthermia (in cases of cocaine or amphetamine intoxication). Intravenous fluids should be administered as soon as possible. Other psychiatric and medical complication should receive appropriate symptomatic treatment. Research on immunotherapies, including vaccines, monoclonal and catalytic antibodies, seems to be a promising approach that may yield specific antidotes for drugs of abuse, helping to ameliorate the morbidity and mortality associated with illicit drug intoxications.

High-dose glycine treatment of refractory obsessive-compulsive disorder and body dysmorphic disorder in a 5-year period

This paper describes an individual who was diagnosed with obsessive-compulsive disorder (OCD) and body dysmorphic disorder (BDD) at age 17 when education was discontinued. By age 19, he was housebound without social contacts except for parents. Adequate trials of three selective serotonin reuptake inhibitors, two with atypical neuroleptics, were ineffective. Major exacerbations following ear infections involving Group A β-hemolytic streptococcus at ages 19 and 20 led to intravenous immune globulin therapy, which was also ineffective. At age 22, another severe exacerbation followed antibiotic treatment for H. pylori. This led to a hypothesis that postulates deficient signal transduction by the N-methyl-D-aspartate receptor (NMDAR). Treatment with glycine, an NMDAR coagonist, over 5 years led to robust reduction of OCD/BDD signs and symptoms except for partial relapses during treatment cessation. Education and social life were resumed and evidence suggests improved cognition. Our findings motivate further study of glycine treatment of OCD and BDD.

Chloroquine psychosis masquerading as PCP: a case report

Chloroquine and its derivatives have been drugs of choice in the prophylaxis and treatment of malaria for over 50 years. These drugs are also frequently used in the treatment of various rheumatologic disorders. Because many Americans now travel abroad and may require chloroquine prophylaxis, as well as the fact that such medications are readily available through Internet-based supply houses, clinicians should be aware of the potential toxicity associated with the use of these agents. We present the case of an adolescent female who presented with acute, chloroquine-induced toxic psychosis resembling that induced by phencyclidine (PCP) in clinical presentation and laboratory findings. In the acute setting, the differentiation between chloroquine toxic psychosis and PCP psychosis may be difficult. Therefore, the syndrome of chloroquine-induced psychosis is reviewed and its differentiation from PCP psychosis highlighted as it relates to important aspects of this case.

Multidisciplinary approach of organic catatonia in children and adolescents may improve treatment decision making

Catatonia is an infrequent but severe condition in young people. Organic diseases may be associated and need to be investigated though no specific recommendations and guidelines are available. We extensively reviewed the literature of all the cases of organic catatonia in children and adolescents from January 1969 to June 2007. We screened socio-demographic characteristics, organic diagnosis, clinical characteristics and treatment. We found 38 cases of children and adolescents with catatonia due to an organic condition. The catatonic syndrome occurred in 21 (57%) females and 16 (43%) males. The mean age of patients was 14.5 years (+/-3.39) [range=7-18 years], and three died from their condition. The organic conditions included infectious diseases (N=10), neurological conditions (N=10), toxic induced states (N=12) and genetic conditions including inborn errors of metabolism (N=6). The onset was dominantly acute, and the clinical presentation most frequently stuporous. Although benzodiazepines were recommended as primary symptomatic treatment, they were rarely prescribed. In several cases, therapeutic approach was related to organic cause (e.g., plasma exchange in lupus erythematosus; copper chelators in Wilson's disease). Based on this review and on our own experience of catatonia in youth, we proposed a consensual and multidisciplinary diagnostic strategy to help practitioners to identify underlying organic diseases.

Models of schizophrenia in humans and animals based on inhibition of NMDA receptors

The research of the glutamatergic system in schizophrenia has advanced with the use of non-competitive antagonists of glutamate NMDA receptors (phencyclidine, ketamine, and dizocilpine), which change both human and animal behaviour and induce schizophrenia-like manifestations. Models based on both acute and chronic administration of these substances in humans and rats show phenomenological validity and are suitable for searching for new substances with antipsychotic effects. Nevertheless, pathophysiology of schizophrenia remains unexplained. In the light of the neurodevelopmental model of schizophrenia based on early administration of NMDA receptor antagonists it seems that increased cellular destruction by apoptosis or changes in function of glutamatergic NMDA receptors in the early development of central nervous system are decisive for subsequent development of psychosis, which often does not manifest itself until adulthood. Chronic administration of antagonists initializes a number of adaptation mechanisms, which correlate with findings obtained in patients with schizophrenia; therefore, this model is also suitable for research into pathophysiology of this disease.

The intoxicated child

Psychiatric disorders and substance abuse occur frequently together, which leads to difficulty in assessment and treatment. An awareness of the prevalence and manifestations of psychiatric diagnoses is essential for the quality treatment of adolescents who abuse substances. The clinician should keep up-to-date on psychopharmacologic interventions [65, 83]. Frequently, the use of psychiatric medications, such as antidepressants, mood stabilizers, and psychostimulants, is beneficial. Care must be taken, however, to avoid potential interactions between the illicit drugs and the prescribed medications [151]. Use of groups such as Alcoholics Anonymous, Narcotics Anonymous, or "Double-Trouble" groups, which deal with mentally ill and chemical abusing or dual diagnosis issues, often can be a useful adjunct to treatment with a mental health professional [152-154]. Careful observation, history taking, and appropriate consultation result in better detection and treatment of comorbid medical and psychiatric disorders and the initial substance abuse problem.

A microsatellite repeat in the promoter of the N-methyl-D-aspartate receptor 2A subunit (GRIN2A) gene suppresses transcriptional activity and correlates with chronic outcome in schizophrenia

Hypofunction of the N-methyl-D-aspartate (NMDA) receptor has been hypothesized to underlie the pathophysiology of schizophrenia, based on the observation that non-competitive antagonists of the NMDA receptor, such as phencyclidine, induce schizophrenia-like symptoms. Mice lacking the NR2A subunit of the NMDA receptor complex are known to display abnormal behaviour, similar to schizophrenic symptoms. The expression of NR2A starts at puberty, a period corresponding to the clinical onset of schizophrenia. This evidence suggests that the NR2A (GRIN2A) gene may play a role in the development of schizophrenia and disease phenotypes. In this study, we performed a genetic analysis of this gene in schizophrenia. Analysis of the GRIN2A gene detected four single nucleotide polymorphisms, and a variable (GT)(n) repeat in the promoter region of the gene. A case-control study (375 schizophrenics and 378 controls) demonstrated evidence of an association between the repeat polymorphism and the disease (P = 0.05, Mann-Whitney test), with longer alleles overly represented in patients. An in-vitro promoter assay revealed a length dependent inhibition of transcriptional activity by the (GT)(n) repeat, which was consistent with a receptor binding assay in postmortem brains. Significantly, the score of symptom severity in chronic patients correlated with repeat size (P = 0.01, Spearman's Rank test). These results illustrate a genotype-phenotype correlation in schizophrenia and suggest that the longer (GT)(n) stretch may act as a risk-conferring factor that worsens chronic outcome by reducing GRIN2A levels in the brain.

Vaccines against drugs of abuse: a viable treatment option?

Drug addiction is a chronically relapsing brain disorder. There is an urgent need for new treatment options for this disease because the relapse rate among drug abusers seeking treatment is quite high. During the past decade, many groups have explored the feasibility of using vaccines directed against drugs of abuse as a means of eliminating illicit drug use as well as drug overdose and neurotoxicity. Vaccines work by inducing drug-specific antibodies in the bloodstream that bind to the drug of abuse and prevent its entry into the brain. The majority of work in this area has been conducted with vaccines and antibodies directed against cocaine and nicotine. On the basis of preclinical work, vaccines for cocaine and nicotine are now in clinical trials because they can offer long-term protection with minimal treatment compliance. In addition, vaccines and antibodies for phencyclidine, methamphetamine and heroin abuse are currently under development. An underlying theme in this research is the need for high concentrations of circulating drug-specific antibodies to reduce drug-seeking and drug-taking behaviour when the drug is repeatedly available, especially in high doses. Although vaccines against drugs of abuse may become a viable treatment option, there are several drawbacks that need to be considered. These include: a lack of protection against a structurally dissimilar drug that produces the same effects as the drug of choice;a lack of an effect on drug craving that predisposes an addict to relapse; and tremendous individual variability in antibody formation. Forced or coerced vaccination is not likely to work from a scientific perspective, and also carries serious legal and ethical concerns. All things considered, vaccination against a drug of abuse is likely to work best with individuals who are highly motivated to quit using drugs altogether and as part of a comprehensive treatment programme. As such, the medical treatment of drug abuse will not be radically different from treatment of other chronic diseases.

Catatonia in childhood and adolescence

Child and adolescent catatonia has been poorly investigated. A literature review was undertaken to clarify phenomenology, diagnosis, etiology, and treatment as well as ethical problems of catatonia in childhood and adolescence. Although there are no accepted standardized criteria for catatonia in childhood and adolescence, catatonic features described by child psychiatrists are similar to Diagnostic and Statistical Manual of Mental Disorders (4th edn; DSM-IV) criteria for catatonia. With respect to etiology, the motor and behavioral symptoms that are part of catatonia bear some similarities with those seen in autism. Several case reports suggest an association between catatonia and general medical conditions. Certain drugs abused by youngsters as well as prescribed medicine can induce catatonia. Regarding catatonic cases originally diagnosed as schizophrenia, it is unclear whether all of these cases should be identified as schizophrenia or whether some of them are pervasive developmental disorders that develop psychic features in adolescence. Environmental changes preceding the onset of catatonia in patients with mood disorder play a possibly important role. Examples that suggest stress-induced catatonia, although rare, also exist. A few patients exhibit features of malignant catatonia, some without taking neuroleptics and others having taken them. Benzodiazepines and electroconvulsive therapy are considered to be effective treatments for catatonic youngsters.

NMDA receptor regulation of memory and behavior in humans

N-methyl-D-aspartate (NMDA) receptor hypofunction is associated with a range of effects on cognition and behavior in whole animal and human studies. NMDA receptor hypofunction within the brain, which can be induced experimentally in vivo using NMDA receptor antagonist drugs, produces adverse effects on memory function. The results suggest that NMDA receptor hypofunction can preferentially affect neural mechanisms regulating the efficiency of encoding and consolidation into longer-term storage. More pronounced NMDA receptor hypofunction can produce a clinical syndrome that includes core features of psychosis, as well as dissociation. Finally, sustained and severe underexcitation of NMDA receptors in the adult brain is associated with a neurotoxic process with well-characterized neuropathological features. Progressive increases in severity of NMDA receptor hypofunction within the brain can produce a range of effects on brain function, involving local and distributed circuitry, which may underlie the observed changes in behavior. As the brain ages, the NMDA receptor system becomes progressively hypofunctional, potentially contributing to further age-related decreases in memory and learning performance. Pharmacological and genomic methods for preventing NMDA receptor hypofunction, or for preventing the upstream or downstream consequences modeled by treatment with NMDA antagonists, may be applicable to the prevention and treatment of memory and behavioral dysfunction in a variety of neuropsychiatric disease conditions.

Increased discriminative stimulus potency of phencyclidine in C57B1/6 mice infected with the LP-BM5 retrovirus

Drug discrimination procedures in mice are used to study the neuropharmacology of a wide variety of drugs. In C57 B1/6 mice, infection with the LP-BM5 murine leukemia virus leads to a syndrome (murine acquired immunodeficiency syndrome-MAIDS) characterized by immunocompromise, neurochemical alterations, and learning and memory deficits. Because the neurochemical and behavioral changes suggest that altered glutamatergic neurotransmission follows LP-BM5 infection, we studied the effects of infection on discriminative stimulus properties of phencyclidine (PCP), a Ca2+ channel blocker at NMDA receptors. We also tested D-amphetamine and dizocilpine to assess the specificity of the discrimination. As expected, dizocilpine produced PCP-like responding. After animals were trained to discriminate PCP from saline, they were inoculated with LP-BM5 and the PCP dose-response functions repeatedly determined. The potency of PCP in this procedure was unchanged 3 weeks after infection, but was increased approximately fivefold 6 and 9 weeks after infection. Amphetamine 9 weeks after inoculation did not produce PCP-like responding, showing that the results were not caused by a loss of specificity of the discrimination. The time course for changes in PCP potency is similar to those of other behavioral and neurochemical changes reported after LP-BM5 infection. The results are consistent with an action of LP-BM5 infection at glutamatergic synapses.

Age-specific neurotoxicity in the rat associated with NMDA receptor blockade: potential relevance to schizophrenia?

Agents that block the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor induce a schizophrenialike psychosis in adult humans and injure or kill neurons in several corticolimbic regions of the adult rat brain. Susceptibility to the psychotomimetic effects of the NMDA antagonist, ketamine is minimal or absent in children and becomes maximal in early adulthood. We examined the sensitivity of rats at various ages to the neurotoxic effects of the powerful NMDA antagonist, MK-801. Vulnerability was found to be age dependent, having onset at approximately puberty (45 days of age) and becoming maximal in early adulthood. This age-dependency profile (onset of susceptibility in late adolescence) in the rat is similar to that for ketamine-induced psychosis or schizophrenia in humans. These findings suggest that NMDA receptor hypofunction, the mechanism underlying the neurotoxic and psychotomimetic actions of NMDA antagonists, may also play a role in schizophrenia.

Fluoxetine and the serotonin syndrome

A 48-year-old man presented to the emergency department with confusion, agitation, diaphoresis, and muscle rigidity after beginning treatment with fluoxetine, a serotonin reuptake inhibitor. He had discontinued treatment with tranylcypromine, a monoamine oxidase inhibitor, 2 weeks earlier. The constellation of findings was diagnostic of the serotonin syndrome.

Phencyclidine exposure alters in vitro cellular immune response parameters associated with host defense

Phencyclidine hydrochloride (PCP) was tested for its ability to alter a variety of immune effector and regulatory functions in vitro. B6C3F1 murine splenic lymphocytes or elicited peritoneal macrophages were cultured in vitro with medium only or medium containing 10(-10)-10(-4) M PCP. Macrophages cultured with or without PCP were stimulated with lipopolysaccharide, and production of interleukin 6 (IL-6) and tumor necrosis factor (TNF) was assessed by bioassay. Cytotoxic T-cell effector function was determined following 5-day lymphocyte co-culture with tumor stimulator cells in the presence of PCP. In addition, the ability of T-lymphocytes to produce specific immunoregulatory cytokines IL-2 and IL-4 in the presence of PCP was quantitated by bioassay. B-lymphocyte function was determined by quantitating lymphocyte proliferation following stimulation with anti-IgM antibody and murine IL-4. Natural immunity was assessed by culturing lymphocytes with or without PCP for 24 h, then quantitating basal and IL-2 augmented natural killer (NK) cell activity. In the absence of effects on cell viability, significant suppression of IL-2 production by T-cells was noted at pharmacologically relevant PCP concentrations (1 microM). In vitro concentrations of 10 microM suppressed the generation of specifically sensitized cytotoxic T-cells. In addition, PCP significantly suppressed both IL-2-augmented NK function as well as B-lymphocyte proliferation. By comparison, macrophage IL-6 production was not affected by any concentration of PCP examined in this study.