Anil K. Malhotra

Cardiometabolic Risk of Second-Generation Antipsychotic Medications During First-Time Use in Children and Adolescents

CONTEXT Cardiometabolic effects of second-generation antipsychotic medications are concerning but have not been sufficiently studied in pediatric and adolescent patients naive to antipsychotic medication. OBJECTIVE To study the association of second-generation antipsychotic medications with body composition and metabolic parameters in patients without prior antipsychotic medication exposure. DESIGN, SETTING, AND PATIENTS Nonrandomized Second-Generation Antipsychotic Treatment Indications, Effectiveness and Tolerability in Youth (SATIETY) cohort study, conducted between December 2001 and September 2007 at semi-urban, tertiary care, academic inpatient and outpatient clinics in Queens, New York, with a catchment area of 4.5-million individuals. Of 505 youth aged 4 to 19 years with 1 week or less of antipsychotic medication exposure, 338 were enrolled (66.9%). Of these patients, 272 had at least 1 postbaseline assessment (80.5%), and 205 patients [corrected] completed the study (60.7%). Patients had mood spectrum (n = 130; 47.8%), schizophrenia spectrum (n = 82; 30.1%), and disruptive or aggressive behavior spectrum (n = 60; 22.1%) disorders. Fifteen patients who refused participation or were nonadherent served as a comparison group. INTERVENTION Treatment with aripiprazole, olanzapine, quetiapine, or risperidone for 12 weeks. MAIN OUTCOME MEASURES Weight gain and changes in lipid and metabolic parameters. RESULTS After a median of 10.8 weeks (interquartile range, 10.5-11.2 weeks) of treatment, weight increased by 8.5 kg (95% confidence interval [CI], 7.4 to 9.7 kg) with olanzapine (n = 45), by 6.1 kg (95% CI, 4.9 to 7.2 kg) with quetiapine (n = 36), by 5.3 kg (95% CI, 4.8 to 5.9 kg) with risperidone (n = 135), and by 4.4 kg (95% CI, 3.7 to 5.2 kg) with aripiprazole (n = 41) compared with the minimal weight change of 0.2 kg (95% CI, -1.0 to 1.4 kg) in the untreated comparison group (n = 15). With olanzapine and quetiapine, respectively, mean levels increased significantly for total cholesterol (15.6 mg/dL [95% CI, 6.9 to 24.3 mg/dL] P < .001 and 9.1 mg/dL [95% CI, 0.4 to 17.7 mg/dL] P = .046), triglycerides (24.3 mg/dL [95% CI, 9.8 to 38.9 mg/dL] P = .002 and 37.0 mg/dL [95% CI, 10.1 to 63.8 mg/dL] P = .01), non-high-density lipoprotein (HDL) cholesterol (16.8 mg/dL [95% CI, 9.3 to 24.3 mg/dL] P < .001 and 9.9 mg/dL [95% CI, 1.4 to 18.4 mg/dL] P = .03), and ratio of triglycerides to HDL cholesterol (0.6 [95% CI, 0.2 to 0.9] P = .002 and (1.2 [95% CI, 0.4 to 2.0] P = .004). With risperidone, triglycerides increased significantly (mean level, 9.7 mg/dL [95% CI, 0.5 to 19.0 mg/dL]; P = .04). Metabolic baseline-to-end-point changes were not significant with aripiprazole or in the untreated comparison group. CONCLUSIONS First-time second-generation antipsychotic medication use was associated with significant weight gain with each medication. Metabolic changes varied among the 4 antipsychotic medications.

NMDA receptor function and human cognition: the effects of ketamine in healthy volunteers.

A rapidly growing body of preclinical data has implicated the glutamatergic N-methyl-d-aspartate (NMDA) receptor in memory and other cognitive processes. There is comparatively less information about this receptor system in human cognition. We examined the effects of subanesthetic doses of ketamine, a noncompetitive NMDA receptor antagonist, on two forms of memory, free recall and recognition, as well as attention and behavior in a double-blind, placebo-controlled, 1-hour infusion in 15 healthy volunteers. Ketamine produced decrements in free recall, recognition memory, and attention. In addition, ketamine induced a brief psychosis in our healthy volunteers marked by thought disorder and withdrawal-retardation. Ketamine-induced memory impairments were not accounted for by changes in subjects attention and were not significantly related to psychosis ratings. These data suggest that the NMDA receptor plays a direct role in two types of explicit memory. The implications of these data for the pathophysiology of schizophremia are discussed.

Microduplications of 16p11.2 are associated with schizophrenia.

Recurrent microdeletions and microduplications of a 600-kb genomic region of chromosome 16p11.2 have been implicated in childhood-onset developmental disorders. We report the association of 16p11.2 microduplications with schizophrenia in two large cohorts. The microduplication was detected in 12/1,906 (0.63%) cases and 1/3,971 (0.03%) controls (P = 1.2 × 10−5, OR = 25.8) from the initial cohort, and in 9/2,645 (0.34%) cases and 1/2,420 (0.04%) controls (P = 0.022, OR = 8.3) of the replication cohort. The 16p11.2 microduplication was associated with a 14.5-fold increased risk of schizophrenia (95% CI (3.3, 62)) in the combined sample. A meta-analysis of datasets for multiple psychiatric disorders showed a significant association of the microduplication with schizophrenia (P = 4.8 × 10−7), bipolar disorder (P = 0.017) and autism (P = 1.9 × 10−7). In contrast, the reciprocal microdeletion was associated only with autism and developmental disorders (P = 2.3 × 10−13). Head circumference was larger in patients with the microdeletion than in patients with the microduplication (P = 0.0007).

Disrupted in schizophrenia 1 (DISC1): association with schizophrenia, schizoaffective disorder, and bipolar disorder.

Schizophrenia, schizoaffective disorder, and bipolar disorder are common psychiatric disorders with high heritabilities and variable phenotypes. The Disrupted in Schizophrenia 1 (DISC1) gene, on chromosome 1q42, was originally discovered and linked to schizophrenia in a Scottish kindred carrying a balanced translocation that disrupts DISC1 and DISC2. More recently, DISC1 was linked to schizophrenia, broadly defined, in the general Finnish population, through the undertransmission to affected women of a common haplotype from the region of intron 1/exon 2. We present data from a case-control study of a North American white population, confirming the underrepresentation of a common haplotype of the intron 1/exon 2 region in individuals with schizoaffective disorder. Multiple haplotypes contained within four haplotype blocks extending between exon 1 and exon 9 are associated with schizophrenia, schizoaffective disorder, and bipolar disorder. We also find overrepresentation of the exon 9 missense allele Phe607 in schizoaffective disorder. These data support the idea that these apparently distinct disorders have at least a partially convergent etiology and that variation at the DISC1 locus predisposes individuals to a variety of psychiatric disorders.

Brain-derived neurotrophic factor Val66met polymorphism and volume of the hippocampal formation

Magnetic resonance (MR) imaging studies have identified hippocampal structural alterations in the pathogenesis of schizophrenia. Brain-derived neurotrophic factor (BDNF) is one of the neurotrophins that is widely expressed in the hippocampal formation and has been implicated in the neurobiology of schizophrenia. Polymorphisms in the BDNF gene may therefore confer risk for schizophrenia through hippocampal pathogenesis and/or making the hippocampus more susceptible to environmental insults. In this study, we investigated whether val66met, a functional and abundant missense polymorphism in the coding region of the BDNF gene, was associated with the volume of the hippocampal formation in 19 patients with first-episode schizophrenia and 25 healthy volunteers. A total of 124 contiguous T1-weighted coronal MR images (slice thickness=1.5 mm) were acquired through the whole head using a 3D Fast SPGR IR Prep sequence on a 1.5 T GE imaging system. Volumes of the right and left hippocampal formation were measured manually by an operator blind to group status and genotype. All participants were genotyped for the BDNF val66met locus. Mixed model analyses revealed a main effect of BDNF val66met genotype such that in the combined sample of patients and healthy volunteers, val/val homozygotes (N=27) had larger volumes of the hippocampal formation compared to val/met heterozygotes (N=17). In separate analyses by group, however, val66met genotype accounted for a greater proportion of the variance in the volume of the hippocampal formation in patients compared to healthy volunteers. These findings implicate genetic involvement of BDNF in variation of human hippocampal volume and suggest that this effect may be greater among patients compared to healthy volunteers.

Converging evidence for a pseudoautosomal cytokine receptor gene locus in schizophrenia

Schizophrenia is a strongly heritable disorder, and identification of potential candidate genes has accelerated in recent years. Genomewide scans have identified multiple large linkage regions across the genome, with fine-mapping studies and other investigations of biologically plausible targets demonstrating several promising candidate genes of modest effect. The recent introduction of technological platforms for whole-genome association (WGA) studies can provide an opportunity to rapidly identify novel targets, although no WGA studies have been reported in the psychiatric literature to date. We report results of a case–control WGA study in schizophrenia, examining ∼500 000 markers, which revealed a strong effect (P=3.7 × 10−7) of a novel locus (rs4129148) near the CSF2RA (colony stimulating factor, receptor 2 alpha) gene in the pseudoautosomal region. Sequencing of CSF2RA and its neighbor, IL3RA (interleukin 3 receptor alpha) in an independent case–control cohort revealed both common intronic haplotypes and several novel, rare missense variants associated with schizophrenia. The presence of cytokine receptor abnormalities in schizophrenia may help explain prior epidemiologic data relating the risk for this illness to altered rates of autoimmune disorders, prenatal infection and familial leukemia.

Fine mapping of ZNF804A and genome-wide significant evidence for its involvement in schizophrenia and bipolar disorder

A recent genome-wide association study (GWAS) reported evidence for association between rs1344706 within ZNF804A (encoding zinc-finger protein 804A) and schizophrenia (P=1.61 × 10−7), and stronger evidence when the phenotype was broadened to include bipolar disorder (P=9.96 × 10−9). In this study we provide additional evidence for association through meta-analysis of a larger data set (schizophrenia/schizoaffective disorder N=18 945, schizophrenia plus bipolar disorder N=21 274 and controls N=38 675). We also sought to better localize the association signal using a combination of de novo polymorphism discovery in exons, pooled de novo polymorphism discovery spanning the genomic sequence of the locus and high-density linkage disequilibrium (LD) mapping. The meta-analysis provided evidence for association between rs1344706 that surpasses widely accepted benchmarks of significance by several orders of magnitude for both schizophrenia (P=2.5 × 10−11, odds ratio (OR) 1.10, 95% confidence interval 1.07–1.14) and schizophrenia and bipolar disorder combined (P=4.1 × 10−13, OR 1.11, 95% confidence interval 1.07–1.14). After de novo polymorphism discovery and detailed association analysis, rs1344706 remained the most strongly associated marker in the gene. The allelic association at the ZNF804A locus is now one of the most compelling in schizophrenia to date, and supports the accumulating data suggesting overlapping genetic risk between schizophrenia and bipolar disorder.

Effects of Ketamine on Thought Disorder, Working Memory, and Semantic Memory in Healthy Volunteers

BACKGROUND The N-methyl-D-aspartate receptor antagonist, ketamine, produces a clinical syndrome of thought disorder, perceptual distortion, and cognitive impairment. METHODS We have administered ketamine to healthy volunteers to characterize the formal thought disorder and specific memory dysfunction associated with ketamine. Ten healthy volunteers underwent a double-blind, placebo-controlled, ketamine infusion (0.12 mg/kg bolus and 0.65 mg/kg/hour). Thought disorder was evaluated with the Scale for the Assessment of Thought, Language and Communication. Cognitive testing involved working and semantic memory tasks. RESULTS Ketamine produced a formal thought disorder, as well as impairments in working and semantic memory. The degree of ketamine-induced thought disorder significantly correlated with ketamine-induced decreases in working memory and did not correlate with ketamine-induced impairments in semantic memory. CONCLUSIONS This study characterizes the formal thought disorder associated with ketamine and may suggest that ketamine-induced deficits in working memory are associated with ketamine-induced thought disorder.

Runs of homozygosity reveal highly penetrant recessive loci in schizophrenia

Evolutionarily significant selective sweeps may result in long stretches of homozygous polymorphisms in individuals from outbred populations. We developed whole-genome homozygosity association (WGHA) methodology to characterize this phenomenon in healthy individuals and to use this genomic feature to identify genetic risk loci for schizophrenia (SCZ). Applying WGHA to 178 SCZ cases and 144 healthy controls genotyped at 500,000 markers, we found that runs of homozygosity (ROHs), ranging in size from 200 kb to 15 mb, were common in unrelated Caucasians. Properties of common ROHs in healthy subjects, including chromosomal location and presence of nonancestral haplotypes, converged with prior reports identifying regions under selective pressure. This interpretation was further supported by analysis of multiethnic HapMap samples genotyped with the same markers. ROHs were significantly more common in SCZ cases, and a set of nine ROHs significantly differentiated cases from controls. Four of these 9 “risk ROHs” contained or neighbored genes associated with SCZ (NOS1AP, ATF2, NSF, and PIK3C3). Several of these risk ROHs were very rare in healthy subjects, suggesting that recessive effects of relatively high penetrance may explain a proportion of the genetic liability for SCZ. Other risk ROHs feature haplotypes that are also common in healthy individuals, possibly indicating a source of balancing selection.

Impaired attention as an endophenotype for molecular genetic studies of schizophrenia.

Attentional abnormalities have long been known to characterize patients with schizophrenia. The data discussed in this report suggest that impaired attention (at least as measured by a specific task, the Continuous Performance Test, Identical Pairs (CPT-IP) version) may also be an endophenotype of particular promise for use in molecular genetic studies of schizophrenia. This conclusion is based on findings indicating that the deficits in verbal and spatial attentional processing tapped by the CPT-IP are heritable, developmentally stable, independent of clinical state, and predict future spectrum disorders in the at-risk offspring of parents with schizophrenia.