Effects of clozapine on auditory event-related potentials in schizophrenia

BACKGROUND

Schizophrenia is associated with cognitive deficits that are an intrinsic component of the disorder. Clozapine is an atypical antipsychotic that is superior to typical agents in the treatment of positive symptoms. The degree to which clozapine ameliorates cognitive deficits, however, is still controversial. Mismatch negativity (MMN), N200 (N2), and P300 (P3) are cognitive event-related potentials (ERPs) that index preattentive (MMN) and attention-dependent information processing (N2, P3) and provide a measure of cognitive deficits associated with schizophrenia. In schizophrenic patients deficient generation of MMN, N2, and P3 has been observed, suggesting impairments of discrete stages of information processing.

METHODS

This study investigates the effects of clozapine treatment on MMN, N2, and P3 generation. Patients were recruited from a haloperidol-controlled, double-blind treatment study of clozapine in chronic schizophrenia. ERPs were obtained at the beginning of the study and after 9 weeks (4 patients) and 16 weeks (13 patients) of treatment.

RESULTS

Clozapine treatment was associated with a significant increase of P3 amplitude, which was not observed in the haloperidol group; however, clozapine treatment did not affect deficits in MMN and N2.

CONCLUSIONS

These findings suggest that clozapine--in contrast to conventional antipsychotics--improves electrophysiological measures of attention-dependent information processing, but does not ameliorate preattentive deficits.

The role of brain computed tomography in evaluating children with new onset of seizures in the emergency department

BACKGROUND

The purpose of neuroimaging of a patient with new onset of seizures is to demonstrate cause and explore the prognosis. It was recently recommended that emergency brain computed tomography (CT) be performed only in adult seizure patients with an increased likelihood of life-threatening lesions, i.e., those with new focal deficits, persistent altered mental status, fever, recent trauma, persistent headaches, history of cancer, history of anticoagulation, or suspicion of acquired immunodeficiency syndrome. The objective of this study was to determine the diagnostic utility of emergency brain CT in children who present to the emergency department with new onset of seizures.

METHODS

A 1-year retrospective chart review of all children who presented to the emergency department of the Schneider Children's Hospital with a new onset of seizures and who underwent CT of the brain, excluding children with simple febrile seizures.

RESULTS

Sixty-six patients, 34 boys and 32 girls with a mean age of 4.9 years, qualified for inclusion in the study. Fifty-two patients (78.8%) had normal CT results and 14 patients (21.2%) had abnormal CT results. Seizure cause was considered cryptogenic in 33 patients, of whom 2 (6%) had abnormal CT results; neither patient required intervention. Seizure cause was considered symptomatic in 20 patients, of whom 12 (60%) had abnormal CT results (p < 0.0001). In two patients with abnormal CT scans (both acute symptomatic), the imaging findings were of immediate therapeutic significance and were predictable from the clinical history and the physical examination. None of the 13 patients with complex febrile seizure cause had an abnormal CT scan. Patients with partial convulsive seizures were more likely to have abnormal CT scans than patients with generalized convulsive seizures, but the difference was not statistically significant.

CONCLUSIONS

The routine practice in many pediatric emergency departments of obtaining brain CT scans for all patients with new onset of nonfebrile seizures is unjustified. History and physical examination are sufficient to identify those patients for whom such studies are likely to be appropriate. Emergent CT is not indicated for patients with no known seizure risk factors, normal neurological examinations, no acute symptomatic cause other than fever, and reliable neurological follow-up. For these patients, referral to a pediatric neurologist for further workup, including electroencephalography and the more diagnostically valuable magnetic resonance imaging, would be more appropriate.

Mismatch detection and the latency of temporal judgements

Event-related potentials were recorded in two auditory tasks involving the discrimination of pitch or duration of binaurally presented tones. Frequently-presented nontarget tones, when compared to the same tones in a simple reaction time task, elicited two negative peaks, NA1 and NA2, followed by a positive peak, nontarget positivity. Infrequently-presented target tones, when compared to the nontargets, elicited mismatch negativity (MMN), followed by N2 and P3b. The peak latencies of NA1 and NA2 did not differ between the pitch and duration tasks, but the duration of NA1 and the peak latencies of mismatch negativity, N2, and P3b, as well as reaction time, increased in parallel for the duration task. It is proposed that the NA1-nontarget positivity sequence reflects the initiation, maintenance, and termination of an attention-modulated process, which is required for the performance of an auditory discrimination task, and that the MMN-N2-P3b sequence reflects a process elicited by infrequently-presented targets, which is the main determinant of reaction time under these testing conditions.

Schizophrenia and Nogo: elevated mRNA in cortex, and high prevalence of a homozygous CAA insert

Schizophrenia is a major psychiatric disorder which is hypothesized to result from abnormal neurodevelopment or neural changes in adulthood and possibly associated with altered gene expression. To search for genes overexpressed in schizophrenia, cDNA library subtractive hybridization experiments between post-mortem human frontal cerebral cortices from schizophrenia individuals and neurological controls were carried out. One of the genes over-expressed in schizophrenia was identified as Nogo (also known as reticulon 4, RTN4, NI 250, or RTN-X), a myelin-associated protein which inhibits the outgrowth of neurites and nerve terminals. The elevated expression of Nogo mRNA in schizophrenia was confirmed by quantitative reverse transcription-polymerase chain reaction studies: 16.5 pg Nogo cDNA/microg total RNA in schizophrenia, and 10.2 pg Nogo cDNA/microg total RNA in controls (n=7; P=0.01, t-test for n<30). To identify possible polymorphisms in this gene, the Nogo nucleotide sequence was determined in a series of schizophrenia and control samples. The Nogo mRNA was found to contain a CAA insert polymorphism in the 3'-untranslated region. The prevalence of individuals homozygous for this CAA insert was significantly higher in schizophrenia compared to controls in genomic DNA samples extracted from post-mortem brain and blood samples: 17/81 or 21% in schizophrenia and 2/61 or 3% in controls (P=0.0022, chi(2)- and Fisher's exact-tests). Because the 3'-untranslated regions of eukaryotic genes are known to regulate gene expression, the increased frequency of the Nogo CAA insert in schizophrenia may contribute to abnormal regulation of Nogo gene expression, and may indicate a role for Nogo in disturbed neurodevelopment in schizophrenia.

The chronometry of attention-modulated processing and automatic mismatch detection

Event-related potentials were recorded from normal subjects in an auditory selective attention task. Targets were rare longer (170-ms) tones of a designated pitch, embedded in a sequence of 100-ms standard tones. The effects of attention-modulated processing were evident in the event-related potentials elicited by the standards. Those to relevant standards were similar for easy (1000 Hz vs. 2000 Hz) and hard (1000 Hz vs. 1030 Hz) pitch separations, and were more negative frontocentrally than those to irrelevant standards. Difference waveforms (attended minus unattended standards) revealed Nd, a negative deflection that was earlier in latency for the easy task (onset, 120 ms; peak, 250 ms) than for the hard task (onset, 250 ms; peak, 350 ms). The speed of detection of the deviant longer tones was insensitive to the attention-modulated processes indexed by Nd. Median reaction time did not differ between tasks, although there were more misses and false alarms in the hard task (and nearly all of the latter were to the irrelevant longer tones). Neither direction of attention nor task difficulty affected the latency of mismatch negativity, N2, or P3 (as identified in difference waveforms: attended or unattended longer tones minus their respective standards). The data suggest that performance was guided by two independent but converging processes, automatic mismatch detection of the longer tone and attention-modulated processing of pitch, followed by selection of response.

Review article: dose optimisation of infliximab for acute severe ulcerative colitis

BACKGROUND

Although optimal medical management of acute severe ulcerative colitis (UC) is ill-defined, infliximab has become a standard of care. Accumulating evidence suggests an increased rate of infliximab clearance in patients with acute severe UC and a reduced colectomy rate with an intensified infliximab induction regimen.

AIM

To assess the strength of the current evidence for the relationship between infliximab pharmacokinetics, dosing strategies and disease behaviour in patients with acute severe UC.

METHODS

We systematically searched MEDLINE and conference proceedings from 2000 to 2016 for relevant articles describing the pharmacokinetics of infliximab in acute severe UC and/or infliximab dose intensification strategies in acute severe UC. Eligible articles described randomised controlled trials, and cohort, cross-sectional, and case-controlled studies.

RESULTS

Of 400 citations identified, 76 studies were eligible. Increased infliximab clearance occurs in patients with acute severe UC, and is driven by the total inflammatory burden and leakage of drug into the colonic lumen. Several cohort studies suggest that infliximab dose intensification is beneficial to at least 50% of acute severe UC patients and the results of case-controlled studies indicate that an intensified infliximab dosing regimen with 1-2 additional infusions in the first 3 weeks of treatment could reduce the early (3-month) colectomy rate by up to 80%, although these data require prospective validation.

CONCLUSIONS

Uncontrolled studies suggest a benefit for infliximab dose optimisation in patients with acute severe UC. A randomised controlled trial in acute severe UC patients comparing a personalised infliximab dose-optimisation strategy with conventional dosing is a research priority.

Increased expression of calcium/calmodulin-dependent protein kinase IIβ in frontal cortex in schizophrenia and depression

In searching for genes dysregulated in schizophrenia, we measured the expression of the two splice variants of calcium/calmodulin-dependent protein kinase II (CaMKIIalpha and CaMKIIbeta) in postmortem frontal cerebral cortex tissues from patients who had died with schizophrenia, bipolar disorder, or severe depression. The mRNA levels of expression of these two splice variants were measured by real-time Quantitative PCR, using an Mx4000 instrument. The values for the expression of CaMKIIalpha and CaMKIIbeta were normalized by the expression of beta-glucuronidase in the tissues. The expression of CaMKIIalpha was significantly elevated in the depression tissues by 29%. The expression of CaMKIIbeta was significantly elevated in the schizophrenia tissues by 27%, and in the depression tissues by 36%. Because CaMKIIbeta influences the expression of many neuroreceptors and influences neural outgrowth and pruning, its altered expression in the cerebral cortex in schizophrenia or depression may contribute to these diseases.

The value of early postictal EEG in children with complex febrile seizures

PURPOSE

To assess the usefulness of an early postictal EEG in neurologically normal children with complex febrile seizures.

METHODS

We conducted a retrospective chart review of all neurologically normal children who were hospitalized over a period of 2.5 years after complex febrile seizures, and had an EEG up to 1 week after the seizure.

RESULTS

Thirty-three patients (mean age, 17.8 months) qualified for inclusion into the study. Twenty-four patients were qualified as complex cases based on one factor (prolonged in 9, repetitive in 13, and focal in 2). Nine other patients had two complex factors: in six patients, the seizures were long and repetitive; in two patients, the seizures were focal and repetitive; and in one patient, the seizures were long, focal, and repetitive. Thirteen (39%) patients experienced prior febrile seizures. All 33 patients had a normal postictal sleep EEG. Our results indicate with a 95% probability that the true rate of abnormalities in an early postictal EEG performed on otherwise normal children with complex febrile seizures is 8.6% or less.

CONCLUSIONS

The yield of abnormalities of an early postictal EEG in this population is low and similar to the reported rate of abnormalities in children with simple febrile seizures. The routine practice of obtaining an early EEG in neurologically normal children with complex febrile seizures is not justified.

Schizophrenia: elevated mRNA for dopamine D2(Longer) receptors in frontal cortex

Because dopamine D2 receptors are the primary targets for antipsychotic drugs, including clozapine and quetiapine, and because some studies have found D2 receptors to be elevated in schizophrenia, we examined the mRNA of three forms of the D2 receptor, particularly the new form of the dopamine D2 receptor, D2(Longer), in post-mortem brains from patients who died with schizophrenia. Using quantitative competitive RT-PCR (reverse transcriptase-polymerase chain reaction), the D2(Longer) mRNA was higher in the frontal cortex, compared to control tissues. The mRNA concentration of D2(Long) and D2(Short) was also higher in the frontal cortex, compared to control tissues. Although most of the schizophrenia patients had received different antipsychotic drugs for varying periods of time, the mRNA of D2(Longer), as well as that for D2(Long) and D2(Short), in such medicated tissues was similar to that in a frontal cortex tissue from a patient who had reliably never received antipsychotic drugs. It is possible, therefore, that the elevation of the mRNAs for D2(Longer), D2(Long) and D2(Short) in the frontal cortex may be related to the disease of schizophrenia itself.

Detection of early FXTAS motor symptoms using the CATSYS computerised neuromotor test battery

BACKGROUND

Carriers of the FMR1 premutation allele are at a significantly increased risk for a late-onset neurodegenerative disorder, fragile X-associated tremor/ataxia syndrome (FXTAS). This disorder is distinct from fragile X syndrome (FXS) in its molecular aetiology and clinical presentation. The primary features of FXTAS are late-onset intention tremor and gait ataxia. Associated features include parkinsonism, neuropsychological dysfunction, autonomic dysfunction and peripheral neuropathy.

AIM

To investigate the usefulness of a quantitative neurological test battery implemented through the CATSYS instrument to identify preclinical symptoms of FXTAS.

METHODS

Both premutation carriers with 70-199 repeats (62 men) and their low-repeat allele carrier siblings (27 men), identified through families with an individual affected with FXS, were tested.

RESULTS

As expected, because of its sensitivity, use of the instrument allowed identification of tremor in 23% of men who had not self-reported tremor, and ataxia in 30% of men who had not self-reported ataxia. Among subjects with self-reported tremor and ataxia, we found significant concordance between measures of the CATSYS system and the self-report.

CONCLUSION

Rates of these traits among premutation carriers and low-repeat allele carrier siblings could be identified, and are presented in this paper, along with the minimum estimates of age-related prevalence.

Risk factors for status epilepticus in children with symptomatic epilepsy

The purpose of this study was to determine risk factors for status epilepticus (SE) in children with symptomatic epilepsy through a retrospective case-control study. Patients (44 children with a prior diagnosis of symptomatic epilepsy experiencing one or more episodes of SE between January 1, 1991, and June 1, 1995) were matched for age at follow-up to controls (88 children with symptomatic epilepsy without SE during that interval) and medical records were reviewed. Patients and controls did not differ in etiology or in age at epilepsy onset (1 year 5 months [SD, 2 years 3 months] versus 1 year 3 months [SD, 1 year 5 months]). Univariate analysis revealed significant associations between SE and several factors, including history of a first seizure as SE, partial epilepsy, partial seizures with secondary generalization, focal paroxysmal abnormalities and focal background abnormalities on EEG, and generalized abnormalities on neuroimaging. Groups did not differ in the proportion of patients on polypharmacy or with subtherapeutic serum antiepileptic drug levels, but there was a trend for greater use of phenobarbital in patients (57% versus 38%, odds ratio (OR) = 2.6, p = 0.057). With multiple logistic regression, four factors emerged as independent predictors of SE risk: focal background EEG abnormalities (OR = 6.51, p = 0.0005), partial seizures with secondary generalization (OR = 4.61, p = 0.0021), first seizure as SE (OR = 3.99, p = 0.034), and generalized abnormalities on neuroimaging (OR = 2.85, p = 0.034). These four factors are indicators of a higher risk of SE in children with symptomatic epilepsy.

Schizophrenia: elevated mRNA for calcium-calmodulin-dependent protein kinase IIbeta in frontal cortex

Because amphetamine releases two to three times more dopamine in schizophrenia patients than in control subjects, and because calcium-calmodulin-dependent protein kinase II has a key role in the enhanced action of amphetamine-induced dopamine release in rats, the synaptic content of calcium-calmodulin-dependent protein kinase IIbeta mRNA was measured (by quantitative competitive RT-PCR; reverse transcriptase-polymerase chain reaction) in seven frontal cerebral cortices of post-mortem brains from patients who had schizophrenia and in seven control tissues. The results indicate that the mRNA of this kinase is elevated in the schizophrenia frontal cortex.

MRI in neonatal dural sinus thrombosis

Dural sinus thrombosis in the newborn period is a rare but underrecognized condition which may cause seizures, macrocephaly, lethargy, and respiratory depression. A 10-day-old term infant with no pre- or perinatal risk factors for thrombosis presented with seizures and was found to have dural sinus thrombosis on computed tomography and magnetic resonance imaging (MRI). One week later, MRI revealed partial resolution and 3 weeks later disclosed a complete resolution of the thrombosis. Clinicians should consider the diagnosis of neonatal dural sinus thrombosis in infants presenting with seizures and/or increased intracranial pressure even in the absence of risk factors or when the cranial computed tomography is normal. MRI is the most sensitive diagnostic tool to establish the diagnosis and permit a noninvasive follow-up, contributing to our understanding of the natural history, associated pathology, and prognosis of this condition.

Replicated association of the NR4A3 gene with smoking behaviour in schizophrenia and in bipolar disorder

Schizophrenia and bipolar disorder are associated with dopamine neurotransmission and show high comorbidity with tobacco dependence. Recent evidence indicates that the family of the NR4A orphan nuclear receptors, which are expressed in dopamine neurons and in dopaminoceptive brain areas, may play a role in dopamine-mediated effects. We have, therefore, analysed the association of six single nucleotide polymorphisms (SNPs) within the three genes belonging to the NR4A orphan nuclear receptor family, NR4A1 (rs2603751, rs2701124), NR4A2 (rs12803, rs834835) and NR4A3 (rs1131339, rs1405209), with the degree of smoking in a sample of 204 unrelated schizophrenia patients, which included 126 smokers and 78 non-smokers. SNPs within the NR4A3 gene (rs1131339 and rs1405209) were significantly associated with heavy smoking in this cohort, using a stepwise analysis of the escalated number of cigarettes smoked per day (P = 0.008 and 0.006, respectively; satisfying the Nyholt significance threshold of 0.009, an adjustment for multiple testing). We then repeated the association analysis of the NR4A3 markers (rs1131339 and rs1405209) in a larger cohort of 319 patients with bipolar disorder, which included 167 smokers and 152 non-smokers. We have replicated the positive association with smoking of the NR4A3 SNP rs1131339 in this group (P = 0.04), providing an important confirmation of the involvement of the NR4A3 gene in nicotine addiction in patients with mental health disease, a population significantly at risk for nicotine addiction.

Valproic acid in the treatment of Sydenham chorea

Severe cases of Sydenham chorea are still difficult to manage because optimal therapy has not been found. In this report severe chorea responded to valproic acid therapy after trials with diazepam and haloperidol had failed. The literature is reviewed and the possible mechanism of action of valproate in this movement disorder is discussed. Valproic acid is proposed as an effective treatment for severe cases of Sydenham chorea.

The use of diagnostic ultrasound in evaluation of the abdomen in primates with emphasis on the rhesus monkey (Macaca mulatta)

To characterize the sonographic appearance of the abdominal organs in primates, a program of routine imaging and diagnostic evaluation was undertaken. Compound B-mode methodology with bistable and grey scale machines was employed utilizing a 2.25- to 3.5-MHZ transducer focused at 7 cm. Visualization of the liver, gallbladder, spleen, kidney and of intraabdominal pathology are described. The stage, position, and condition of a pregnancy can be determined by this methodology.

The production of cerebrospinal fluid in experimental communicating hydrocephalus

Utilizing an atraumatic model to produce chronic hydrocephalus, CSF production was measured during and after development of communicatin hydrocephalus. CSF volume production was significantly lower in animals with increased pressure. Animals with chronic hydrocephalus and normal pressures had abnormal CSF production. Diminished CSF production appears to offer a potential compensatory mechanism when CSF absorption is altered.

Cerebrospinal fluid pressure measurements and radioisotope cisternography in dogs

Cerebrospinal fluid pressure measurements and radioisotope cisternograms were made in 16 mongrel random-source dogs (beagle breed excluded) as a screening technique in developing an experimental animal model for communicating hydrocephalus. Cerebrospinal fluid pressure measurements were made by puncturing the cisterna magna with a spinal needle through which the radiopharmaceutical was also subsequently injected. The mean cerebrospinal fluid pressure was 117 mm water, and the incidence of hydrocephalus was found to be rare. Cisternographic flow patterns also indicate that cerebrospinal fluid flow and absorption in dogs differs from that found in man.

Sensitivity of the Preclinical Alzheimer's Cognitive Composite (PACC), PACC5, and Repeatable Battery for Neuropsychological Status (RBANS) to Amyloid Status in Preclinical Alzheimer's Disease -Atabecestat Phase 2b/3 EARLY Clinical Trial

BACKGROUND

Cognitive composites commonly serve as primary outcomes in Alzheimer's disease (AD) secondary prevention trials.

OBJECTIVE

To evaluate the association between amyloid (Aβ) burden level (+/-) and performance on three separate composite endpoints: Preclinical Alzheimer's Cognitive Composite (PACC), PACC+Semantic Fluency (PACC5), and Repeatable Battery for Neuropsychological Status (RBANS).

DESIGN

Screening data from the randomized, double-blind, placebo-controlled, phase 2b/3 atabecestat EARLY study in preclinical AD participants were used in this analysis.

SETTING

The EARLY study was conducted at 143 centers across 14 countries.

PARTICIPANTS

3,569 cognitively unimpaired older adults (Clinical Dementia Rating of 0; aged 60-85 years) screened for inclusion in the EARLY study with Aβ status and at least PACC or RBANS at screening were included. Participants were categorized as those with non-pathological Aβ levels (Aβ-, n=2,824) and those with pathological Aβ levels (Aβ+, n=745) based on florbetapir uptake or levels of cerebrospinal fluid Aβ1-42.

MEASUREMENTS

Analysis of Covariance models controlling for age, sex, and education were used to examine the difference in PACC, PACC5, and RBANS between Aβ groups. Nonparametric bootstrap was used to compare sensitivity of composites to differentiate between Aβ status.

RESULTS

Of 3,569 participants, 2,116 were women (59%); 3,006 were Caucasian (84%); mean (SD) age was 68.98 (5.28) years. Aβ+ participants performed worse versus Aβ- participants on all cognitive composites though the magnitude of the Aβ effect was generally small. The Aβ+/- effect size for the PACC (Cohen's d=-0.15) was significantly greater than the RBANS (d=-0.097) while the PACC5 effect size (d=-0.139) was numerically larger than the RBANS. When examining subscores from the composites, memory tests (i.e., Free and Cued Selective Reminding Test, Figure Recall) and speed of processing (i.e., Digit-Symbol/Coding on the PACC/RBANS) exhibited the largest Aβ+/- effect sizes.

CONCLUSIONS

Cross-sectional relationships between Aβ and cognition among clinically unimpaired older adults are detectable on multi-domain cognitive composites but are relatively small in magnitude. The Aβ+/- group effect was statistically larger for PACC and marginally larger for PACC5 versus RBANS. However, interpretation of composite sensitivity to Aβ status cross-sectionally cannot be generalized to sensitivity to change over time.