Genome-wide association study of borderline personality disorder reveals genetic overlap with bipolar disorder, major depression and schizophrenia

Borderline personality disorder (BOR) is determined by environmental and genetic factors, and characterized by affective instability and impulsivity, diagnostic symptoms also observed in manic phases of bipolar disorder (BIP). Up to 20% of BIP patients show comorbidity with BOR. This report describes the first case-control genome-wide association study (GWAS) of BOR, performed in one of the largest BOR patient samples worldwide. The focus of our analysis was (i) to detect genes and gene sets involved in BOR and (ii) to investigate the genetic overlap with BIP. As there is considerable genetic overlap between BIP, major depression (MDD) and schizophrenia (SCZ) and a high comorbidity of BOR and MDD, we also analyzed the genetic overlap of BOR with SCZ and MDD. GWAS, gene-based tests and gene-set analyses were performed in 998 BOR patients and 1545 controls. Linkage disequilibrium score regression was used to detect the genetic overlap between BOR and these disorders. Single marker analysis revealed no significant association after correction for multiple testing. Gene-based analysis yielded two significant genes: DPYD (P=4.42 × 10-7) and PKP4 (P=8.67 × 10-7); and gene-set analysis yielded a significant finding for exocytosis (GO:0006887, PFDR=0.019; FDR, false discovery rate). Prior studies have implicated DPYD, PKP4 and exocytosis in BIP and SCZ. The most notable finding of the present study was the genetic overlap of BOR with BIP (rg=0.28 [P=2.99 × 10-3]), SCZ (rg=0.34 [P=4.37 × 10-5]) and MDD (rg=0.57 [P=1.04 × 10-3]). We believe our study is the first to demonstrate that BOR overlaps with BIP, MDD and SCZ on the genetic level. Whether this is confined to transdiagnostic clinical symptoms should be examined in future studies.

Association of Common Polymorphisms in the Nicotinic Acetylcholine Receptor Alpha4 Subunit Gene with an Electrophysiological Endophenotype in a Large Population-Based Sample

Variation in genes coding for nicotinic acetylcholine receptor (nAChR) subunits affect cognitive processes and may contribute to the genetic architecture of neuropsychiatric disorders. Single nucleotide polymorphisms (SNPs) in the CHRNA4 gene that codes for the alpha4 subunit of alpha4/beta2-containing receptors have previously been implicated in aspects of (mostly visual) attention and smoking-related behavioral measures. Here we investigated the effects of six synonymous but functional CHRNA4 exon 5 SNPs on the N100 event-related potential (ERP), an electrophysiological endophenotype elicited by a standard auditory oddball. A total of N = 1,705 subjects randomly selected from the general population were studied with electroencephalography (EEG) as part of the German Multicenter Study on nicotine addiction. Two of the six variants, rs1044396 and neighboring rs1044397, were significantly associated with N100 amplitude. This effect was pronounced in females where we also observed an effect on reaction time. Sequencing of the complete exon 5 region in the population sample excluded the existence of additional/functional variants that may be responsible for the observed effects. This is the first large-scale population-based study investigation the effects of CHRNA4 SNPs on brain activity measures related to stimulus processing and attention. Our results provide further evidence that common synonymous CHRNA4 exon 5 SNPs affect cognitive processes and suggest that they also play a role in the auditory system. As N100 amplitude reduction is considered a schizophrenia-related endophenotype the SNPs studied here may also be associated with schizophrenia outcome measures.

Prenatal adversity: a risk factor in borderline personality disorder?

BACKGROUND

Patients with borderline personality disorder (BPD) show a high prevalence of early adversity, such as childhood trauma. It has also been reported that prenatal adverse conditions, such as prenatal maternal stress, drug taking, tobacco smoking or medical complications, may be associated with an increased risk of mental disorders in the offspring. Prenatal adversity is investigated here for the first time as a potential risk factor in the diagnosis of BPD. Method A total of 100 patients with a DSM-IV diagnosis of BPD and 100 matched healthy controls underwent semi-structured interviews about the course of pregnancy, maternal stressors, birth complications and childhood trauma. Further information was obtained from the participants' mothers and from prenatal medical records.

RESULTS

Borderline patients were significantly more often exposed to adverse intrauterine conditions, such as prenatal tobacco exposure (p=0.004), medical complications (p=0.008), prenatal maternal traumatic stress (p=0.015), familial conflicts (p=0.004), low social support (p=0.004) and partnership problems during pregnancy (p=0.014). Logistic regression analyses revealed that the reported prenatal risk factors accounted for 25.7% of the variance in BPD. Prenatal tobacco exposure [odds ratio (OR) 3.37, 95% confidence interval (CI) 1.49-7.65, p=0.004] and medical complications (OR 2.87, 95% CI 1.29-6.38, p=0.010) emerged as important predictors. After controlling for childhood adversity and parental socio-economic status (SES), prenatal risk factors predicted relevant borderline subdomains, such as impulsivity, affective instability, identity disturbance, dissociation and severity of borderline symptoms.

CONCLUSIONS

This study provides evidence of an association between prenatal adversity and the diagnosis of BPD. Our findings suggest that prenatal adversity may constitute a potential risk factor in the pathogenesis of BPD.

Hippocampal subfields predict positive symptoms in schizophrenia: first evidence from brain morphometry

Alterations of hippocampal anatomy have been reported consistently in schizophrenia. Within the present study, we used FreeSurfer to determine hippocampal subfield volumes in 21 schizophrenic patients. A negative correlation between PANSS-positive symptom score and bilateral hippocampal subfield CA2/3 as well as CA1 volume was found on high-resolution magnetic resonance images. Our observation opens the gate for advanced investigation of the commonly reported hippocampal abnormalities in schizophrenia in terms of specific subfields.

Association of a variant in the muscarinic acetylcholine receptor 2 gene (CHRM2) with nicotine addiction

Genetic factors contribute to the overall risk of developing nicotine addiction, which is the major cause of preventable deaths in western countries. However, knowledge regarding specific polymorphisms influencing smoking phenotypes remains scarce. In the present study we provide evidence that a common single nucleotide polymorphism (SNP) in the 5' untranslated region of CHRM2, the gene coding for the muscarinic acetylcholine receptor 2 is associated with nicotine addiction. CHRM2 was defined as a candidate gene for nicotine addiction based on previous evidence that linked variations in CHRM2 to alcohol and drug dependence. A total of more than 5,500 subjects representative of the German population were genotyped and assessed regarding their smoking habits. The impact of three SNPs in CHRM2 on smoking behavior/nicotine addiction was investigated using logistic regression models or a quasi-Poisson regression model, respectively. We found the T allele of SNP rs324650 to be associated with an increased risk of smoking/nicotine dependence according to three different models, the recessive models of regular or heavy smokers vs. never-smokers (odds ratio 1.17 in both analyses) and according to the Fagerström index of nicotine addiction. In the analysis stratified by gender this association was only found in females. Our data provide further evidence that variations in CHRM2 may be associated with the genetic risk of addiction in general or with certain personality traits that predispose to the development of addiction. Alternatively, variations in CHRM2 could modulate presynaptic auto-regulation in cholinergic systems and may thereby affect an individual's response to nicotine more specifically.

The tolerability of rTMS treatment in schizophrenia with respect to cognitive function

INTRODUCTION

The purpose of this study was to assess tolerability and safety of high-frequency rTMS with regard to cognitive performance when conducted as "add-on" treatment in chronic schizophrenia in-patients (n=32).

METHODS

Patients, who were on stable antipsychotic treatment, were randomly assigned to verum or sham condition (double-blind). In the verum group, ten sessions of 10 Hz rTMS with a total of 10 000 stimuli were applied over the left dorsolateral prefrontal cortex (PFC) at 110% of motor threshold over a period of two weeks. The sham group received corresponding sham stimulation. RTMS effects on cognitive performance were assessed with a neuropsychological test battery consisting of the following tests: trail making test A and B (TMT), Wisconsin card sorting test (WCST), D2 attention task and the "short test of general intelligence" (KAI).

RESULTS

No statistically significant deterioration of cognitive performance was observed as a result of rTMS treatment. Moreover it was shown that in the verum group patients with a less favourable performance on the WCST at baseline tend to improve after rTMS treatment with regard to psychopathology as opposed to patients in the control group.

DISCUSSION

The stability of cognitive function suggests good tolerability of rTMS treatment in schizophrenia. The absence of evidence for cognitive deterioration could be due to low and short stimulation parameters.

Brain activation patterns underlying fast habituation to painful laser stimuli

A painful experience is modified by processes like habituation/antinociception or sensitization. Altered habituation may be one characteristic of chronic pain syndromes. In the present study we sought to investigate the functional magnetic resonance imaging (fMRI) blood oxygen level dependent (BOLD) correlate of rapid habituation to pain using simultaneous single trial electrodermal activity (EDA)/fMRI measurements. A total of N=32 healthy subjects have been investigated. Subjects received painful laser stimulation of the left hand. The fMRI BOLD response was measured simultaneously with continuous EDA recordings. Single trial EDA responses to laser stimulation habituated over time with substantial subject-to-subject differences in the degree and speed of habituation. fMRI BOLD habituation was assessed by contrasting the first half of the experiment against the second half and was found in primary and secondary somatosensory cortices, the insula and the anterior cingulate cortex (ACC). We hypothesized that single trial EDA habituation would reflect BOLD habituation which was investigated separately in subjects with 'faster' (N=15) and 'slower' (N=14) EDA habituation. Significant habituation of the BOLD signal was only found in subjects with 'faster' EDA habituation that was accompanied by a signal increase in the rostral ACC and the periaqueductal grey. Furthermore, subjects with faster EDA habituation provided lower pain ratings. Therefore the EDA habituation profile to painful stimulation may constitute a pain-related (endo)phenotype and may be an informative additional endpoint measure in fMR-imaging of pain, especially when people suffering from chronic pain states in which pain processing is often altered are studied.

Single-trial P3 amplitude and latency informed event-related fMRI models yield different BOLD response patterns to a target detection task

Using single-trial parameters as a regressor in the General Linear Model (GLM) is becoming an increasingly popular method for informing fMRI analysis. However, the parameter used to characterise or to differentiate brain regions involved in the response to a particular task varies across studies (e.g. ERP amplitude, ERP latency, reaction time). Furthermore, the way in which the single-trial information is used in the fMRI analysis is also important. For example, the single-trial parameters can be used as regressors in the GLM or to modify the duration of the events modelled in the GLM. The aim of this study was to investigate the BOLD response to a target detection task when including P3 amplitude, P3 latency and reaction time parameters in the GLM. Simultaneous EEG-fMRI was recorded from fifteen subjects in response to a visual choice reaction time task. Including P3 amplitude as a regressor in the GLM yielded activation in left central opercular cortex, left postcentral gyrus, left insula, left middle frontal gyrus, left insula and left parietal operculum. Using P3 latency and reaction time as an additional regressor yielded no additional activation in comparison with the conventional fMRI analysis. However, when P3 latency or reaction time was used to determine the duration of events at a single-trial level, additional activation was observed in the left postcentral gyrus, left precentral gyrus, anterior cingulate cortex and supramarginal gyrus. Our findings suggest that ERP amplitudes and latencies can yield different activation patterns when used to modify relevant aspects of the GLM.

[Treatment of borderline personality disorder with atypical antipsychotic drugs]

Pharmacotherapy of Borderline personality disorder with atypical antipsychotics has recently been the subject of several mostly small studies and case reports. In contrast to the frequent clinical use of this substance class in borderline patients the amount of data on that subject is still sparse. The clinical data gathered thus far suggest a potential use of atypical antipsychotics in the areas of psychotic symptoms, impulsivity and possibly affective symptoms. The drugs were sufficiently well tolerated; however, the observation period in most studies was short and the dosage low. The current set of clinical data does not support the frequently applied polypharmacy. However, recent data suggest that a therapeutic approach combining atypical antipsychotics and psychotherapy may reveal synergistic effects. Future trials should study larger sample sizes over a longer period of time. Open questions are the required dose and the optimal treatment duration.

Potential clinical targets of repetitive transcranial magnetic stimulation treatment in schizophrenia

Despite the introduction of atypical antipsychotic drugs, treatment-resistant symptoms still represent a serious problem in schizophrenia. Currently, there is evidence from clinical studies suggesting that treatment with repetitive transcranial magnetic stimulation (rTMS) may improve schizophrenia symptoms. Our review provides an overview of clinical rTMS studies in schizophrenic patients. A systematic search of the literature (Cochrane and Medline databases up to December 2005) was conducted. Most studies showed methodological problems due to their explorative character and small sample sizes. In some studies, a treatment effect of high-frequency rTMS applied over the prefrontal cortex was seen with respect to negative symptoms. On the other hand, low-frequency rTMS in the temporal lobe area might lead to a suppression of auditory hallucinations. It is concluded that larger sham-controlled studies are required to allow an adequate assessment of the clinical and neurobiological effects of rTMS in schizophrenic patients. The currently available data provide insufficient evidence to support the use of rTMS as an adjuvant treatment for schizophrenic psychopathology, but encourage further investigation of rTMS as a novel treatment approach.

Aripiprazole Pharmacotherapy of Borderline Personality Disorder

We report three consecutive cases of women with borderline personality disorder with psychotic symptoms, who received pharmacotherapy with the new atypical antipsychotic drug aripiprazole. Therapeutic effects were measured using the SCL-90R (symptom check list) and the BSL (borderline symptom list). We observed different responses to aripiprazole. In the first patient we had to discontinue the drug before we were able to observe any therapeutic effects. The second patient also complained about initial side effects. However, after the dose was lowered, the drug was tolerated and she responded well to aripiprazole with respect to all psychopathological aspects. The third patient did not suffer from any side effects under aripiprazole. She responded partially to the drug. Aripiprazole may have a potential role in the pharmacotherapy of borderline personality disorder and may not only target psychotic symptoms in these patients.

Guillain-Barré Syndrome after Septicemia following Clozapine-Induced Agranulocytosis

We report the case of a patient with schizophrenia, who experienced agranulocytosis during clozapine treatment, followed by bronchopulmonal infection and Guillain-Barré syndrome. The case was recorded within the German surveillance project "drug safety in psychiatry" (AMSP).

[A new method for the treatment of depression: repetitive transcranial magnetic stimulation]

Recent data suggest that repetitive transcranial magnetic stimulation (rTMS) is effective in treating depressive symptoms to a lesser extent compared with classical electroconvulsive therapy. However, rTMS represents an economical and well tolerable procedure in relation to the expenditure of electroconvulsive therapy with anaesthesia. Usually, rTMS is applicated as an add-on-therapy accompanying psychopharmacological treatment. So far, it has predominantly been used for patients with long-standing and so called treatment-refractory symptoms. However, even in the early phase of a depressive episode rTMS would be possibly more effective. In many cases, the standard procedure-application of up to 10 rTMS-sessions will not be enough to produce therapeutic benefit. Therefore rTMS series including up to 20 sessions are recommended. Long-term studies are needed to clarify the role of rTMS for relapse prevention and to determine the optimal frequency and duration of rTMS in such an indication. Although numerous results of newer studies suggest a moderate antidepressive effect of rTMS, its application in daily clinical routine practice cannot be recommended yet. Larger, accurate designed and controlled studies, especially involving patients of old age, are needed to evaluate the true tolerability and effectiveness of rTMS as a new treatment option for depressive symptoms.

Molecular studies of chimerism and minimal residual disease after allogeneic peripheral blood progenitor cell or bone marrow transplantation

We investigated 23 patients for their chimerism status who underwent allogeneic transplantation using peripheral blood progenitor cells (PBPCT) for chronic myelogenous leukemia (CML) (n = 14), acute myelogenous leukemia (AML) (n = 5), acute lymphoblastic leukemia (n = 1), myelodysplasia (MDS) (n = 1), and Hodgkin's disease (HD) (n = 2). These data were compared with those of patients after allogeneic BMT after matching them for disease and disease stage, sex of donor and recipient, GVHD prophylaxis, conditioning therapy and degree of HLA disparity. Patients were studied monthly up to 16 months post-transplant. In 11 of 23 (48%) patients who were transplanted with PBPCs and in 18 of 23 (78%) patients after BMT a mixed chimerism was detected at 1 month post-transplant. After 3 months, six of 21 (29%) evaluable patients after PBPCT remained mixed chimeric as opposed to 12 of 21 (57%) patients after BMT. We also assessed minimal residual disease using detection of the chimeric BCR/ABL transcripts by PCR of CML patients in this study. In four of 14 (29%) patients who underwent PBPCT, the BCR/ABL chimeric transcript was detected, while after BMT eight of 14 (57%) CML patients remained BCR/ABL positive. In two of these BMT patients, a cytogenetic relapse developed subsequently, and one other patient suffered a hematological relapse, whereas one of the CML patients relapsed after PBPCT. The present data may indicate that after PBPCT the incidence of leukemic relapse is similar or even lower than after BMT.