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Featured researches published by Jan Dirk Blom.


The Journal of Clinical Psychiatry | 2010

Should We Expand the Toolbox of Psychiatric Treatment Methods to Include Repetitive Transcranial Magnetic Stimulation (rTMS)? A Meta-Analysis of the Efficacy of rTMS in Psychiatric Disorders

Christina W. Slotema; Jan Dirk Blom; Hans W. Hoek; Iris E. Sommer

OBJECTIVE Repetitive transcranial magnetic stimulation (rTMS) is a safe treatment method with few side effects. However, efficacy for various psychiatric disorders is currently not clear. DATA SOURCES A literature search was performed from 1966 through October 2008 using PubMed, Ovid Medline, Embase Psychiatry, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, and PsycINFO. The following search terms were used: transcranial magnetic stimulation, TMS, repetitive TMS, psychiatry, mental disorder, psychiatric disorder, anxiety disorder, attention-deficit hyperactivity disorder, bipolar disorder, catatonia, mania, depression, obsessive-compulsive disorder, psychosis, posttraumatic stress disorder, schizophrenia, Tourettes syndrome, bulimia nervosa, and addiction. STUDY SELECTION Data were obtained from randomized, sham-controlled studies of rTMS treatment for depression (34 studies), auditory verbal hallucinations (AVH, 7 studies), negative symptoms in schizophrenia (7 studies), and obsessive-compulsive disorder (OCD, 3 studies). Studies of rTMS versus electroconvulsive treatment (ECT, 6 studies) for depression were meta-analyzed. DATA EXTRACTION Standardized mean effect sizes of rTMS versus sham were computed based on pretreatment-posttreatment comparisons. DATA SYNTHESIS The mean weighted effect size of rTMS versus sham for depression was 0.55 (P < .001). Monotherapy with rTMS was more effective than rTMS as adjunctive to antidepressant medication. ECT was superior to rTMS in the treatment of depression (mean weighted effect size -0.47, P = .004). In the treatment of AVH, rTMS was superior to sham treatment, with a mean weighted effect size of 0.54 (P < .001). The mean weighted effect size for rTMS versus sham in the treatment of negative symptoms in schizophrenia was 0.39 (P = .11) and for OCD, 0.15 (P = .52). Side effects were mild, yet more prevalent with high-frequency rTMS at frontal locations. CONCLUSIONS It is time to provide rTMS as a clinical treatment method for depression, for auditory verbal hallucinations, and possibly for negative symptoms. We do not recommend rTMS for the treatment of OCD.


The Journal of Clinical Psychiatry | 2011

The same or different? A phenomenological comparison of auditory verbal hallucinations in healthy and psychotic individuals.

Kirstin Daalman; Marco P. Boks; Kelly M. J. Diederen; Antoin D. de Weijer; Jan Dirk Blom; René S. Kahn; Iris E. Sommer

OBJECTIVE Whereas auditory verbal hallucinations (AVHs) are most characteristic of schizophrenia, their presence has frequently been described in a continuum, ranging from severely psychotic patients to schizotypal personality disorder patients to otherwise healthy participants. It remains unclear whether AVHs at the outer borders of this spectrum are indeed the same phenomenon. Furthermore, specific characteristics of AVHs may be important indicators of a psychotic disorder. METHOD To investigate differences and similarities in AVHs in psychotic and nonpsychotic individuals, the phenomenology of AVHs in 118 psychotic outpatients was compared to that in 111 otherwise healthy individuals, both experiencing AVHs at least once a month. The study was performed between September 2007 and March 2010 at the University Medical Center, Utrecht, the Netherlands. Characteristics of AVHs were quantified using the Psychotic Symptoms Rating Scales Auditory Hallucinations subscale. RESULTS The perceived location of voices (inside/outside the head), the number of voices, loudness, and personification did not differentiate between psychotic and healthy individuals. The most prominent differences between AVHs in healthy and psychotic individuals were the emotional valence of the content, the frequency of AVHs, and the control subjects had over their AVHs (all P values < .001). Age at onset of AVHs was at a significantly younger age in the healthy individuals (P < .001). In our sample, the negative emotional valence of the content of AVHs could accurately predict the presence of a psychotic disorder in 88% of the participants. CONCLUSIONS We cannot ascertain whether AVHs at the outer borders of the spectrum should be considered the same phenomenon, as there are both similarities and differences. The much younger age at onset of AVHs in the healthy subjects compared to that in psychotic patients may suggest a different pathophysiology. The high predictive value of the emotional content of voices implies that inquiring after the emotional content of AVHs may be a crucial step in the diagnosis of psychotic disorders in individuals hearing voices.


Schizophrenia Research | 2006

Incidence of schizophrenia among ethnic minorities in the Netherlands : A four-year first-contact study

Wim Veling; Jean-Paul Selten; Natalie D. Veen; Winfried Laan; Jan Dirk Blom; Hans W. Hoek

There is only one previous report on the first-contact incidence of schizophrenia among immigrants in the Netherlands, which was based on a small number of cases, particularly for second generation immigrants. We conducted another two-year first-contact incidence study in the same geographical area, combined the data of both studies and compared risks over all four years. The incidence of schizophrenia was increased for all first generation non-Western immigrants. The risk was particularly high for second generation immigrants: the age- and gender-adjusted incidence rate ratio was 5.8 (95% CI, 2.9-11.4) for Moroccans, 2.9 (1.6-5.0) for Surinamese, 2.3 (1.0-5.4) for Turks, and 3.5 (1.8-6.8) for immigrants from other non-Western countries.


Schizophrenia Bulletin | 2012

The characteristic features of auditory verbal hallucinations in clinical and nonclinical groups: state-of-the-art overview and future directions.

Frank Laroi; Iris E. Sommer; Jan Dirk Blom; Charles Fernyhough; Dominic H. ffytche; Kenneth Hugdahl; Louise Johns; Simon McCarthy-Jones; Antonio Preti; Andrea Raballo; Christina W. Slotema; Massoud Stephane; Flavie Waters

Despite a growing interest in auditory verbal hallucinations (AVHs) in different clinical and nonclinical groups, the phenomenological characteristics of such experiences have not yet been reviewed and contrasted, limiting our understanding of these phenomena on multiple empirical, theoretical, and clinical levels. We look at some of the most prominent descriptive features of AVHs in schizophrenia (SZ). These are then examined in clinical conditions including substance abuse, Parkinsons disease, epilepsy, dementia, late-onset SZ, mood disorders, borderline personality disorder, hearing impairment, and dissociative disorders. The phenomenological changes linked to AVHs in prepsychotic stages are also outlined, together with a review of AVHs in healthy persons. A discussion of key issues and future research directions concludes the review.


Biological Psychiatry | 2011

Can Low-Frequency Repetitive Transcranial Magnetic Stimulation Really Relieve Medication-Resistant Auditory Verbal Hallucinations? Negative Results from a Large Randomized Controlled Trial

Christina W. Slotema; Jan Dirk Blom; Antoin D. de Weijer; Kelly M. J. Diederen; Rutger Goekoop; Jasper Looijestijn; Kirstin Daalman; Anne-Marije Rijkaart; René S. Kahn; Hans W. Hoek; Iris E. Sommer

BACKGROUND Several studies have applied low-frequency repetitive transcranial magnetic stimulation (rTMS) directed at the left temporoparietal area (TP) for the treatment of auditory verbal hallucinations (AVH), but findings on efficacy are inconsistent. Furthermore, recent functional magnetic resonance imaging (fMRI) studies indicate that the left TP is not a general focus of activation during the experience of AVH. The aims of this study are twofold: to investigate the effects of rTMS on AVH in a double blind, randomized, sham-controlled study; and to investigate whether the efficacy can be improved when rTMS is guided by individual fMRI scans of hallucinatory activation. METHODS Sixty-two patients with medication-resistant AVH were randomized over three conditions: rTMS targeted at the area of maximal hallucinatory activation calculated from individual fMRI scans during AVH, rTMS directed at the left TP, and sham treatment. Repetitive TMS was applied during 15 sessions of 20 min each, at 1 Hz and 90% of the individual motor threshold. The severity of AVH and other psychotic symptoms were monitored during treatment and 3-month follow-up, with the Auditory Hallucination Rating Scale, the Positive and Negative Syndrome Scale, and the Psychotic Symptom Rating Scales. RESULTS The effects of fMRI-guided rTMS and left TP rTMS on the severity of AVH were comparable to those of sham treatment. No differences in severity of general psychotic symptoms were found among the three treatment conditions. CONCLUSIONS Low-frequency rTMS administered to the left TP or to the site of maximal hallucinatory activation is not more effective for medication-resistant AVH than sham treatment.


PLOS ONE | 2012

A Gene Co-Expression Network in Whole Blood of Schizophrenia Patients Is Independent of Antipsychotic-Use and Enriched for Brain-Expressed Genes

Simone de Jong; Marco P. Boks; Tova F Fuller; Eric Strengman; Esther Janson; Carolien G.F. de Kovel; Anil P.S. Ori; Nancy Vi; Flip Mulder; Jan Dirk Blom; Birte Glenthøj; Chris D. Schubart; Wiepke Cahn; René S. Kahn; Steve Horvath; Roel A. Ophoff

Despite large-scale genome-wide association studies (GWAS), the underlying genes for schizophrenia are largely unknown. Additional approaches are therefore required to identify the genetic background of this disorder. Here we report findings from a large gene expression study in peripheral blood of schizophrenia patients and controls. We applied a systems biology approach to genome-wide expression data from whole blood of 92 medicated and 29 antipsychotic-free schizophrenia patients and 118 healthy controls. We show that gene expression profiling in whole blood can identify twelve large gene co-expression modules associated with schizophrenia. Several of these disease related modules are likely to reflect expression changes due to antipsychotic medication. However, two of the disease modules could be replicated in an independent second data set involving antipsychotic-free patients and controls. One of these robustly defined disease modules is significantly enriched with brain-expressed genes and with genetic variants that were implicated in a GWAS study, which could imply a causal role in schizophrenia etiology. The most highly connected intramodular hub gene in this module (ABCF1), is located in, and regulated by the major histocompatibility (MHC) complex, which is intriguing in light of the fact that common allelic variants from the MHC region have been implicated in schizophrenia. This suggests that the MHC increases schizophrenia susceptibility via altered gene expression of regulatory genes in this network.


Schizophrenia Bulletin | 2012

Auditory Hallucinations Elicit Similar Brain Activation in Psychotic and Nonpsychotic Individuals

Kelly M. J. Diederen; Kirstin Daalman; Antoin D. de Weijer; Sebastiaan F. W. Neggers; Willemijn A. van Gastel; Jan Dirk Blom; René S. Kahn; Iris E. Sommer

While auditory verbal hallucinations (AVH) are most characteristic for schizophrenia, they also occur in nonpsychotic individuals in the absence of a psychiatric or neurological disorder and in the absence of substance abuse. At present, it is unclear if AVH in these nonpsychotic individuals constitute the same phenomenon as AVH in psychotic patients. Comparing brain activation during AVH between nonpsychotic and psychotic individuals could provide important clues regarding this question. 21 nonpsychotic subjects with AVH and 21 matched psychotic patients indicated the presence of AVH during 3T functional magnetic resonance imaging (fMRI) scanning. To identify common areas of activation during the experience of AVH in both groups, a conjunction analysis was performed. In addition, a 2-sample t-test was employed to discover possible differences in AVH-related activation between the groups. Several common areas of activation were observed for the psychotic and nonpsychotic subjects during the experience of AVH, consisting of the bilateral inferior frontal gyri, insula, superior temporal gyri, supramarginal gyri and postcentral gyri, left precentral gyrus, inferior parietal lobule, superior temporal pole, and right cerebellum. No significant differences in AVH-related brain activation were present between the groups. The presence of multiple common areas of AVH-related activation in psychotic and nonpsychotic individuals, in the absence of significant differences, implicates the involvement of the same cortical network in the experience of AVH in both groups.


Schizophrenia Bulletin | 2014

Visual Hallucinations in the Psychosis Spectrum and Comparative Information From Neurodegenerative Disorders and Eye Disease

Flavie Waters; Daniel Collerton; Dominique H. ffytche; Renaud Jardri; Delphine Pins; Robert Dudley; Jan Dirk Blom; Urs Peter Mosimann; Frank Eperjesi; Stephen Ford; Frank Laroi

Much of the research on visual hallucinations (VHs) has been conducted in the context of eye disease and neurodegenerative conditions, but little is known about these phenomena in psychiatric and nonclinical populations. The purpose of this article is to bring together current knowledge regarding VHs in the psychosis phenotype and contrast this data with the literature drawn from neurodegenerative disorders and eye disease. The evidence challenges the traditional views that VHs are atypical or uncommon in psychosis. The weighted mean for VHs is 27% in schizophrenia, 15% in affective psychosis, and 7.3% in the general community. VHs are linked to a more severe psychopathological profile and less favorable outcome in psychosis and neurodegenerative conditions. VHs typically co-occur with auditory hallucinations, suggesting a common etiological cause. VHs in psychosis are also remarkably complex, negative in content, and are interpreted to have personal relevance. The cognitive mechanisms of VHs in psychosis have rarely been investigated, but existing studies point to source-monitoring deficits and distortions in top-down mechanisms, although evidence for visual processing deficits, which feature strongly in the organic literature, is lacking. Brain imaging studies point to the activation of visual cortex during hallucinations on a background of structural and connectivity changes within wider brain networks. The relationship between VHs in psychosis, eye disease, and neurodegeneration remains unclear, although the pattern of similarities and differences described in this review suggests that comparative studies may have potentially important clinical and theoretical implications.


Schizophrenia Bulletin | 2012

The Treatment of Hallucinations in Schizophrenia Spectrum Disorders

Iris E. Sommer; Christina W. Slotema; Zafiris J. Daskalakis; Eske M. Derks; Jan Dirk Blom; Mark van der Gaag

This article reviews the treatment of hallucinations in schizophrenia. The first treatment option for hallucinations in schizophrenia is antipsychotic medication, which can induce a rapid decrease in severity. Only 8% of first-episode patients still experience mild to moderate hallucinations after continuing medication for 1 year. Olanzapine, amisulpride, ziprasidone, and quetiapine are equally effective against hallucinations, but haloperidol may be slightly inferior. If the drug of first choice provides inadequate improvement, it is probably best to switch medication after 2-4 weeks of treatment. Clozapine is the drug of choice for patients who are resistant to 2 antipsychotic agents. Blood levels should be above 350-450 μg/ml for maximal effect. For relapse prevention, medication should be continued in the same dose. Depot medication should be considered for all patients because nonadherence is high. Cognitive-behavioral therapy (CBT) can be applied as an augmentation to antipsychotic medication. The success of CBT depends on the reduction of catastrophic appraisals, thereby reducing the concurrent anxiety and distress. CBT aims at reducing the emotional distress associated with auditory hallucinations and develops new coping strategies. Transcranial magnetic stimulation (TMS) is capable of reducing the frequency and severity of auditory hallucinations. Several meta-analyses found significantly better symptom reduction for low-frequency repetitive TMS as compared with placebo. Consequently, TMS currently has the status of a potentially useful treatment method for auditory hallucinations, but only in combination with state of the art antipsychotic treatment. Electroconvulsive therapy (ECT) is considered a last resort for treatment-resistant psychosis. Although several studies showed clinical improvement, a specific reduction in hallucination severity has never been demonstrated.


Journal of Neurology, Neurosurgery, and Psychiatry | 2010

Disorders of visual perception

Dominic H. ffytche; Jan Dirk Blom; Marco Catani

Visual perceptual disorders are often presented as a disparate group of neurological deficits with little consideration given to the wide range of visual symptoms found in psychiatric and neurodevelopmental disease. Here, the authors attempt a functional anatomical classification of all disorders linked to visual perception, whatever the clinical context in which they arise, including those disorders that bridge vision, emotion, memory, language and action. Guided by clinical and neuroimaging evidence, visual perceptual disorders are classified by the functional anatomical networks likely to be involved and the class of underlying dysfunction, whether topological (a localised deficit or region of hyperfunction) or hodological (a disconnection or hyperconnection). The wider perspective forces us to consider what visual functions underlie a range of symptoms sidelined by previous classificatory schemes and helps generate novel hypotheses for further research in the area.

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Iris E. Sommer

University Medical Center Groningen

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Jasper Looijestijn

University Medical Center Groningen

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Flavie Waters

University of Western Australia

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