Multiple inducers and novel roles of autoantibodies against the obligatory NMDAR subunit NR1: a translational study from chronic life stress to brain injury.

Circulating autoantibodies (AB) of different immunoglobulin classes (IgM, IgA, and IgG), directed against the obligatory N-methyl-D-aspartate-receptor subunit NR1 (NMDAR1-AB), belong to the mammalian autoimmune repertoire, and appear with age-dependently high seroprevalence across health and disease. Upon access to the brain, they can exert NMDAR-antagonistic/ketamine-like actions. Still unanswered key questions, addressed here, are conditions of NMDAR1-AB formation/boosting, intraindividual persistence/course in serum over time, and (patho)physiological significance of NMDAR1-AB in modulating neuropsychiatric phenotypes. We demonstrate in a translational fashion from mouse to human that (1) serum NMDAR1-AB fluctuate upon long-term observation, independent of blood-brain barrier (BBB) perturbation; (2) a standardized small brain lesion in juvenile mice leads to increased NMDAR1-AB seroprevalence (IgM + IgG), together with enhanced Ig-class diversity; (3) CTLA4 (immune-checkpoint) genotypes, previously found associated with autoimmune disease, predispose to serum NMDAR1-AB in humans; (4) finally, pursuing our prior findings of an early increase in NMDAR1-AB seroprevalence in human migrants, which implicated chronic life stress as inducer, we independently replicate these results with prospectively recruited refugee minors. Most importantly, we here provide the first experimental evidence in mice of chronic life stress promoting serum NMDAR1-AB (IgA). Strikingly, stress-induced depressive-like behavior in mice and depression/anxiety in humans are reduced in NMDAR1-AB carriers with compromised BBB where NMDAR1-AB can readily reach the brain. To conclude, NMDAR1-AB may have a role as endogenous NMDAR antagonists, formed or boosted under various circumstances, ranging from genetic predisposition to, e.g., tumors, infection, brain injury, and stress, altogether increasing over lifetime, and exerting a spectrum of possible effects, also including beneficial functions.

Uncoupling the widespread occurrence of anti-NMDAR1 autoantibodies from neuropsychiatric disease in a novel autoimmune model.

Autoantibodies of the IgG class against N-methyl-D-aspartate-receptor subunit-NR1 (NMDAR1-AB) were considered pathognomonic for anti-NMDAR encephalitis. This view has been challenged by the age-dependent seroprevalence (up to >20%) of functional NMDAR1-AB of all immunoglobulin classes found in >5000 individuals, healthy or affected by different diseases. These findings question a merely encephalitogenic role of NMDAR1-AB. Here, we show that NMDAR1-AB belong to the normal autoimmune repertoire of dogs, cats, rats, mice, baboons, and rhesus macaques, and are functional in the NMDAR1 internalization assay based on human IPSC-derived cortical neurons. The age dependence of seroprevalence is lost in nonhuman primates in captivity and in human migrants, raising the intriguing possibility that chronic life stress may be related to NMDAR1-AB formation, predominantly of the IgA class. Active immunization of ApoE-/- and ApoE+/+ mice against four peptides of the extracellular NMDAR1 domain or ovalbumin (control) leads to high circulating levels of specific AB. After 4 weeks, the endogenously formed NMDAR1-AB (IgG) induce psychosis-like symptoms upon MK-801 challenge in ApoE-/- mice, characterized by an open blood-brain barrier, but not in their ApoE+/+ littermates, which are indistinguishable from ovalbumin controls. Importantly, NMDAR1-AB do not induce any sign of inflammation in the brain. Immunohistochemical staining for microglial activation markers and T lymphocytes in the hippocampus yields comparable results in ApoE-/- and ApoE+/+ mice, irrespective of immunization against NMDAR1 or ovalbumin. These data suggest that NMDAR1-AB of the IgG class shape behavioral phenotypes upon access to the brain but do not cause brain inflammation on their own.

Violent aggression predicted by multiple pre-adult environmental hits.

Early exposure to negative environmental impact shapes individual behavior and potentially contributes to any mental disease. We reported previously that accumulated environmental risk markedly decreases age at schizophrenia onset. Follow-up of matched extreme group individuals (≤1 vs. ≥3 risks) unexpectedly revealed that high-risk subjects had >5 times greater probability of forensic hospitalization. In line with longstanding sociological theories, we hypothesized that risk accumulation before adulthood induces violent aggression and criminal conduct, independent of mental illness. We determined in 6 independent cohorts (4 schizophrenia and 2 general population samples) pre-adult risk exposure, comprising urbanicity, migration, physical and sexual abuse as primary, and cannabis or alcohol as secondary hits. All single hits by themselves were marginally associated with higher violent aggression. Most strikingly, however, their accumulation strongly predicted violent aggression (odds ratio 10.5). An epigenome-wide association scan to detect differential methylation of blood-derived DNA of selected extreme group individuals yielded overall negative results. Conversely, determination in peripheral blood mononuclear cells of histone-deacetylase1 mRNA as 'umbrella mediator' of epigenetic processes revealed an increase in the high-risk group, suggesting lasting epigenetic alterations. Together, we provide sound evidence of a disease-independent unfortunate relationship between well-defined pre-adult environmental hits and violent aggression, calling for more efficient prevention.

Impact of childhood trauma on cognitive profile in bipolar disorder.

OBJECTIVES: Bipolar Disorder (BD) is associated with cognitive impairment even during remission periods. Nonetheless, this impairment seems to adjust to different profiles of severity. Our aim was to examine the potential impact of childhood trauma (CT) on cognitive performance and, more specifically, on neurocognitive profile membership. METHODS: Using a data-driven strategy, 113 euthymic bipolar patients were grouped according to their cognitive performance using a hierarchical clustering technique. Patients from the three resulting clusters, the so-called "low", "average", and "high performance" groups, were then compared in terms of main sociodemographic, clinical and functioning variables, including CT measures. One-way ANOVA, a chi-square test and partial correlations were used for this purpose, as appropriate. A multinomial logistic regression model was used to determine which variables contributed to neurocognitive clustering membership. RESULTS: Patients from the three neurocognitive clusters differed in terms of sociodemographic, clinical, functioning and CT variables. Scores on the Childhood Trauma Questionnaire (CTQ), especially on the physical negligence subscale, were also associated with a poor cognitive performance. The multinomial regression model indicated that CTQ total scores and the estimated intelligence quotient (IQ) significantly contributed to differentiation among the three neurocognitive groups. CONCLUSIONS: Our results confirmed that CT significantly impacts on cognitive performance during adulthood in BD. The data obtained suggest that a history of CT could act as a liability marker for cognitive impairment. A higher estimated IQ may act as a protective factor against cognitive decline in this group of patients.

Hypothalamic-pituitary-adrenal system, neurotrophic factors and clozapine response: association with FKBP5 and NTRK2 genes.

Clozapine is an atypical antipsychotic drug known as being more effective compared with traditional antipsychotics for patients with poor response or resistance to treatment. It has been demonstrated that clozapine modulates hypothalamic-pituitary-adrenal activity and affects central brain-derived neurotrophic factor levels, which could explain part of its therapeutic efficacy. In this study, we investigated the role of genes related to the hypothalamic-pituitary-adrenal axis (FKBP5 and NR3C1) and neurotrophic factors (BDNF and NTRK2) in clinical response to clozapine in 591 schizophrenia patients. We found significant allelic and genotype associations between FKBP5-rs1360780, NTRK2-rs1778929 and NTRK2-rs10465180 polymorphisms and clozapine response. The haplotypes composed of rs1360780-rs3777747-rs17542466-rs2766533 (FKBP5) and rs1619120-rs1778929-rs10465180 (NTRK2) were also nominally significant. Our results suggest that genetic variability in FKBP5 and NTRK2 genes may partially explain clinical response to clozapine. Further studies are needed to clarify the involvement of these genes in clinical response to atypical antipsychotics.

Exploring Genetic Variability at PI, GSK3, HPA, and Glutamatergic Pathways in Lithium Response: Association With IMPA2, INPP1, and GSK3B Genes.

Lithium is considered the first-line treatment in bipolar disorder, although response could range from an excellent response to a complete lack of response. Response to lithium is a complex phenotype in which different factors, part of them genetics, are involved. In this sense, the aim of this study was to investigate the potential association of genetic variability at genes related to phosphoinositide, glycogen synthetase kinase-3 (GSK3), hypothalamic-pituitary-adrenal, and glutamatergic pathways with lithium response. A sample of 131 bipolar patients (99 type I, 32 type II) were grouped and compared according to their level of response: excellent responders (ER), partial responders (PR), and nonresponders (NR). Genotype and allele distributions of the rs669838 (IMPA2), rs909270 (INNP1), rs11921360 (GSK3B), and rs28522620 (GRIK2) polymorphisms significantly differed between ER, PR, and NR. When we compared the ER versus PR+NR, the logistic regression showed significant association for rs669838-C (IMPA2; P = 0.021), rs909270-G (INPP1; P = 0.009), and rs11921360-A (GSK3B; P = 0.004) with lithium nonresponse. Haplotype analysis showed significant association for the haplotypes rs3791809-rs4853694-rs909270 (INPP1) and rs1732170-rs11921360-rs334558 (GSK3B) and lithium response. Our study is in line with previous studies reporting association between genetic variability at these genes and lithium response, pointing to an effect of IMPA2, INPP1, and GSK3B genes to lithium response in bipolar disorder patients. Further studies with larger samples are warranted to assess the strength of the reported associations.

Shared vulnerability and sex-dependent polygenic burden in psychotic disorders.

Evidence suggests a remarkable shared genetic susceptibility between psychiatric disorders. However, sex-dependent differences have been less studied. We explored the contribution of schizophrenia (SCZ), bipolar disorder (BD) and major depressive disorder (MDD) polygenic scores (PGSs) on the risk for psychotic disorders and whether sex-dependent differences exist (CIBERSAM sample: 1826 patients and 1372 controls). All PGSs were significantly associated with psychosis. Sex-stratified analyses showed that the variance explained in psychotic disorders risk was significantly higher in males than in females for all PGSs. Our results confirm the shared genetic architecture across psychotic disorders and demonstrate sex-dependent differences in the vulnerability to psychotic disorders.

Lithium response in bipolar disorder: Epigenome-wide DNA methylation signatures and epigenetic aging.

Lithium (Li) is the first-line treatment for bipolar disorder (BD) even though only 30 % of BD patients are considered excellent responders. The mechanisms by which Li exerts its action are not clearly understood, but it has been suggested that specific epigenetic mechanisms, such as methylation processes, may play a role. In this regard, DNA methylation patterns can be used to estimate epigenetic age (EpiAge), which is accelerated in BD patients and reversed by Li treatment. Our first aim was to compare the DNA methylation profile in peripheral blood between BD patients categorized as excellent responders to Li (Ex-Rp) and non-responders (N-Rp). Secondly, EpiAge was estimated to detect differential age acceleration between the two groups. A total of 130 differentially methylated positions (DMPs) and 16 differentially methylated regions (DMRs) between Ex-Rp (n = 26) and N-Rp (n = 37) were identified (FDR adjusted p-value < 0.05). We found 122 genes mapping the DMPs and DMRs, nine of which (HOXB6, HOXB3, HOXB-AS3, TENM2, CACNA1B, ANK3, EEF2K, CYP1A1, and SORCS2) had previously been linked to Li response. We found genes related to the GSK3ß pathway to be highly represented. Using FUMA, we found enrichment in Gene Ontology Cell Component for the synapse. Gene network analysis highlighted functions related to the cell cycle, nervous system development and function, and gene expression. No significant differences in age acceleration were found between Ex-Rp and N-Rp for any of the epigenetic clocks analysed. Our findings indicate that a specific methylation pattern could determine the response to Li in BD patients. We also found that a significant portion of the differentially methylated genes are closely associated with the GSK3ß pathway, reinforcing the role of this system in Li response. Future longitudinal studies with larger samples will help to elucidate the epigenetic mechanisms underlying Li response.

Genetic contribution to the comorbidity between attention-deficit/hyperactivity disorder and substance use disorders.

We characterized the genetic architecture of the attention-deficit hyperactivity disorder-substance use disorder (ADHD-SUD) relationship by investigating genetic correlation, causality, pleiotropy, and common polygenic risk. Summary statistics from genome-wide association studies (GWAS) were used to investigate ADHD (Neff = 51,568), cannabis use disorder (CanUD, Neff = 161,053), opioid use disorder (OUD, Neff = 57,120), problematic alcohol use (PAU, Neff = 502,272), and problematic tobacco use (PTU, Neff = 97,836). ADHD, CanUD, and OUD GWAS meta-analyses included cohorts with case definitions based on different diagnostic criteria. PAU GWAS combined information related to alcohol use disorder, alcohol dependence, and the items related to alcohol problematic consequences assessed by the alcohol use disorders identification test. PTU GWAS was generated a multi-trait analysis including information regarding Fagerström Test for Nicotine Dependence and cigarettes per day. Linkage disequilibrium score regression analyses indicated positive genetic correlation with CanUD, OUD, PAU, and PTU. Genomic structural equation modeling showed that these genetic correlations were related to two latent factors: one including ADHD, CanUD, and PTU and the other with OUD and PAU. The evidence of a causal effect of PAU and PTU on ADHD was stronger than the reverse in the two-sample Mendelian randomization analysis. Conversely, similar strength of evidence was found between ADHD and CanUD. CADM2 rs62250713 was a pleiotropic SNP between ADHD and all SUDs. We found seven, one, and twenty-eight pleiotropic variants between ADHD and CanUD, PAU, and PTU, respectively. Finally, OUD, CanUD, and PAU PRS were associated with increased odds of ADHD. Our findings demonstrated the contribution of multiple pleiotropic mechanisms to the comorbidity between ADHD and SUDs.

TPH1, MAOA, serotonin receptor 2A and 2C genes in citalopram response: possible effect in melancholic and psychotic depression.

BACKGROUND: Serotonergic genes have been widely investigated regarding antidepressant response in major depressive disorder (MDD) but results are still not univocal. METHODS: 159 MDD patients treated with citalopram were genotyped and evaluated by the 21-item Hamilton Depression Rating Scale at the beginning and every 4 weeks during the 12-week follow-up. Four serotonin-related genetic variants were tested for association with treatment outcome: tryptophane hydroxylase 1 (TPH1) rs1800532, monoamine oxidase A µVNTR, serotonin 2A receptor rs6311 and serotonin 2C receptor rs6318. The effect of these polymorphisms was tested both in the whole sample and in depressive subtypes with usually higher clinical severity: psychotic and melancholic MDD. RESULTS: No effect on response, remission and symptom improvement was found for the four polymorphisms. However, rs1800532 was found to affect the outcome depending on the MDD subtype: the A allele predicted worse response both in MDD with psychotic (F6,378 = 2.90; p = 0.009) and melancholic (F6,381 = 2.86; p = 0.0097) features. CONCLUSIONS: The A allele at TPH1 rs1800532 may be associated with citalopram efficacy only in melancholic and psychotic MDD. These results suggest the usefulness of investigating the effect of genetic variants in conjunction with specific clinical features.

The genetics of depression: what information can new methodologic approaches provide?

Major depressive disorder is a genetically complex disease involving several minor, or susceptibility, genes whose expression may be modulated by many environmental factors. From the classical early linkage studies to the complete genome-wide association (GWA) study methodologies, it is evident that it is difficult to understand the genetic bases of this mental disorder. Many studies have identified one or more gene regions whose variability confers a small risk for developing depressive disorder, explaining a small percentage of the total genetic component of disease with low predictive value. Although the results to date are inconclusive, new approaches based on gene-environment interactions and biological pathway analysis (based on GWA studies) open new and promising perspectives in the investigation of the genetic and biological basis of major depression.

Genetic differences between bipolar disorder subtypes: A systematic review focused in bipolar disorder type II.

BACKGROUND: The identification of bipolar disorder (BD) type II patients has both treatment and prognostic implications. Better understanding of its underlying genetics may yield useful diagnostic tools. METHODS: A systematic review on BDII genetics was done using articles published in 2009-2019, following PRISMA recommendations. RESULTS: The most studied polymorphism was BDNF Val66Met with several gene-gene interactions within the dopaminergic system. Associations were reported within the monoaminergic systems (DRD3, ADH1B and SLC6A4), calcium (CACNB2 and CACNG2) and cAMP (PDE1DA, PDE4B and DISC1) signal transduction pathways and the immune system (TNFα, IFNδ and IL-10). Chromosomes 2, 3 and 10 were associated with BDII and polygenic risk scores distinguished between BD subtypes and with major depressive disorder. CONCLUSIONS: Research on BDII stems from BDI findings, however with a stronger contribution of gene-gene interactions and low-effect alleles on known neuroplasticity and monoaminergic system genes. Genome studies point to transdiagnostic backgrounds, with wider associations across bipolar spectrum disorders. Findings able to accurately differentiate BDII remain elusive, dependent on better phenotypic characterization and new research methods.

Excitation-inhibition dysbalance as predictor of autistic phenotypes.

Autistic traits are normally distributed across health and disease, with autism spectrum disorders (ASD) at the extreme end. As we learned from mutations of synaptic or synapse regulating genes, leading to monogenetic forms of autism, the heterogeneous etiologies of ASD converge at the synapse. They result in a mild synaptic dysfunction as the final common pathway, also addressed as synaptopathy. Based on genetic rodent models and EEG/MEG findings in autists, a neuronal excitation-inhibition dysbalance is considered autism-pathognomonic. We hypothesized that this objectively measurable consequence is not restricted to the diagnosis of ASD but transcends disease borders and is of quantitative rather than qualitative nature. For proof-of-principle, we conducted a transcranial magnetic stimulation (TMS) study, monitoring corticospinal excitability and intracortical inhibition of the motor cortex. Employing the GRAS data collection of N > 1200 deep-phenotyped schizophrenic subjects, we had the chance to select for this study N = 20 perfectly matched men. They differed highly significantly by autistic trait severity, as assessed using PANSS autism severity score (PAUSS), capturing the continuum of autistic behaviors. Applying TMS to these men, we provide first intriguing hints of a positive correlation of autistic phenotype severity with functional cortical correlates, mainly alterations in GABAergic system and ion channels. This 'dose-response relationship' between severity of autistic traits and excitation-inhibition ratio in non-ASD subjects underlines the biological basis of this continuous trait. Based on these data, TMS may evolve as new add-on biomarker of autistic traits across disease groups. Finally, common treatment strategies targeting the excitation-inhibition dysbalance in humans may develop. To ultimately achieve this goal, however, replication studies with larger numbers of individuals would be desirable.

Association between genetic variation in the myo-inositol monophosphatase 2 (IMPA2) gene and age at onset of bipolar disorder.

INTRODUCTION: The age at onset of bipolar disorder (BD) has significant implications for severity, duration of affective episodes, response to treatment, and psychiatric comorbidities. It has been suggested that early-onset BD (EO-BD) could represent a clinically distinct subtype with probable genetic risk factors different from those of late-onset BD (LO-BD). To date, several genes have been associated with BD risk but few studies have investigated the genetic differences between EO-BD and LO-BD. The aim of this study was to evaluate if variants of the gene coding for myo-inositol monophosphatase (IMPA2) are linked to age at onset of BD. METHOD: 235 bipolar patients were recruited and assessed. The final sample consisting of 192 euthymic individuals, was compared according to the age at onset. Polymorphisms were genotyped in the IMPA2 gene (rs669838, rs1020294, rs1250171, and rs630110). Early-onset was defined by the appearance of a first affective episode before the age of 18. RESULTS: The analyses showed that in the genotype distribution rs1020294 (p = .01) and rs1250171 (p = .01) were associated with the age at onset. The significant effect remained only in the rs1020294 SNP in which G carriers were more likely to debut later compared to patients presenting the AA genotype (p = .002; OR = 9.57, CI95%[2.37-38.64]). The results also showed that EO-BD tended to experience more alcohol misuse (p = .003; OR = .197, CI95%[.07-.58]) compared to LO-BD. CONCLUSIONS: Our results provide evidence for genetic differences between EO-BD and LO-BD at the IMPA2 gene as well as clinical differences between subgroups with therapeutic implications.

Convergence of placenta biology and genetic risk for schizophrenia.

Defining the environmental context in which genes enhance disease susceptibility can provide insight into the pathogenesis of complex disorders. We report that the intra-uterine environment modulates the association of schizophrenia with genomic risk (in this study, genome-wide association study-derived polygenic risk scores (PRSs)). In independent samples from the United States, Italy, and Germany, the liability of schizophrenia explained by PRS is more than five times greater in the presence of early-life complications (ELCs) compared with their absence. Patients with ELC histories have significantly higher PRS than patients without ELC histories, which is confirmed in additional samples from Germany and Japan. The gene set composed of schizophrenia loci that interact with ELCs is highly expressed in placenta, is differentially expressed in placentae from complicated in comparison with normal pregnancies, and is differentially upregulated in placentae from male compared with female offspring. Pathway analyses reveal that genes driving the PRS-ELC interaction are involved in cellular stress response; genes that do not drive such interaction implicate orthogonal biological processes (for example, synaptic function). We conclude that a subset of the most significant genetic variants associated with schizophrenia converge on a developmental trajectory sensitive to events that affect the placental response to stress, which may offer insights into sex biases and primary prevention.

Microglia ablation alleviates myelin-associated catatonic signs in mice.

The underlying cellular mechanisms of catatonia, an executive "psychomotor" syndrome that is observed across neuropsychiatric diseases, have remained obscure. In humans and mice, reduced expression of the structural myelin protein CNP is associated with catatonic signs in an age-dependent manner, pointing to the involvement of myelin-producing oligodendrocytes. Here, we showed that the underlying cause of catatonic signs is the low-grade inflammation of white matter tracts, which marks a final common pathway in Cnp-deficient and other mutant mice with minor myelin abnormalities. The inhibitor of CSF1 receptor kinase signaling PLX5622 depleted microglia and alleviated the catatonic symptoms of Cnp mutants. Thus, microglia and low-grade inflammation of myelinated tracts emerged as the trigger of a previously unexplained mental condition. We observed a very high (25%) prevalence of individuals with catatonic signs in a deeply phenotyped schizophrenia sample (n = 1095). Additionally, we found the loss-of-function allele of a myelin-specific gene (CNP rs2070106-AA) associated with catatonia in 2 independent schizophrenia cohorts and also associated with white matter hyperintensities in a general population sample. Since the catatonic syndrome is likely a surrogate marker for other executive function defects, we suggest that microglia-directed therapies may be considered in psychiatric disorders associated with myelin abnormalities.

A normal genetic variation modulates synaptic MMP-9 protein levels and the severity of schizophrenia symptoms.

Matrix metalloproteinase 9 (MMP-9) has recently emerged as a molecule that contributes to pathological synaptic plasticity in schizophrenia, but explanation of the underlying mechanisms has been missing. In the present study, we performed a phenotype-based genetic association study (PGAS) in > 1,000 schizophrenia patients from the Göttingen Research Association for Schizophrenia (GRAS) data collection and found an association between the MMP-9 rs20544 C/T single-nucleotide polymorphism (SNP) located in the 3'untranslated region (UTR) and the severity of a chronic delusional syndrome. In cultured neurons, the rs20544 SNP influenced synaptic MMP-9 activity and the morphology of dendritic spines. We demonstrated that Fragile X mental retardation protein (FMRP) bound the MMP-9 3'UTR We also found dramatic changes in RNA structure folding and alterations in the affinity of FMRP for MMP-9 RNA, depending on the SNP variant. Finally, we observed greater sensitivity to psychosis-related locomotor hyperactivity in Mmp-9 heterozygous mice. We propose a novel mechanism that involves MMP-9-dependent changes in dendritic spine morphology and the pathophysiology of schizophrenia, providing the first mechanistic insights into the way in which the single base change in the MMP-9 gene (rs20544) influences gene function and results in phenotypic changes observed in schizophrenia patients.

Correction: Predicting Response Trajectories during Cognitive-Behavioural Therapy for Panic Disorder: No Association with the BDNF Gene or Childhood Maltreatment.

[This corrects the article DOI: 10.1371/journal.pone.0158224.].

Predicting Response Trajectories during Cognitive-Behavioural Therapy for Panic Disorder: No Association with the BDNF Gene or Childhood Maltreatment.

BACKGROUND: Anxiety disorders are highly prevalent and result in low quality of life and a high social and economic cost. The efficacy of cognitive-behavioural therapy (CBT) for anxiety disorders is well established, but a substantial proportion of patients do not respond to this treatment. Understanding which genetic and environmental factors are responsible for this differential response to treatment is a key step towards "personalized medicine". Based on previous research, our objective was to test whether the BDNF Val66Met polymorphism and/or childhood maltreatment are associated with response trajectories during exposure-based CBT for panic disorder (PD). METHOD: We used Growth Mixture Modeling to identify latent classes of change (response trajectories) in patients with PD (N = 97) who underwent group manualized exposure-based CBT. We conducted logistic regression to investigate the effect on these trajectories of the BDNF Val66Met polymorphism and two different types of childhood maltreatment, abuse and neglect. RESULTS: We identified two response trajectories ("high response" and "low response"), and found that they were not significantly associated with either the genetic (BDNF Val66Met polymorphism) or childhood trauma-related variables of interest, nor with an interaction between these variables. CONCLUSIONS: We found no evidence to support an effect of the BDNF gene or childhood trauma-related variables on CBT outcome in PD. Future studies in this field may benefit from looking at other genotypes or using different (e.g. whole-genome) approaches.