title: Meta-analysis of repetitive transcranial magnetic stimulation in the treatment of auditory verbal hallucinations: update and effects after one month.
abstract: OBJECTIVE
  Several meta-analyses considering repetitive transcranial magnetic stimulation (rTMS) for auditory verbal hallucinations (AVH) have been performed with moderate to high mean weighted effect sizes. Since then several negative findings were reported in relatively large samples. The aim of this study was to provide an update of the literature on the efficacy of rTMS for AVH and to investigate the effect of rTMS one month after the end of treatment.
  
  
  METHODS
  A literature search was performed from 1966 through August 2012 using Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, Embase Psychiatry, Ovid Medline, PsycINFO and PubMed. Randomized, double blind, sham-controlled studies with severity of AVH or severity of psychosis as an outcome measure were included.
  
  
  METHODS
  Data were obtained from 17 randomized studies of rTMS for AVH. Five studies fulfilled the criteria for the meta-analysis on the effect of rTMS one month after the end of treatment.
  
  
  METHODS
  Standardized mean weighted effect sizes of rTMS versus sham were computed on pre- and posttreatment comparisons.
  
  
  RESULTS
  The mean weighted effect size of rTMS directed at the left temporoparietal area was 0.44 (95% CI 0.19-0.68). A separate meta-analysis including studies directing rTMS at other brain regions revealed a mean weighted effect size of 0.33 (95% CI 0.17-0.50) in favor of real TMS. The effect of rTMS was no longer significant at one month of follow-up (mean weighted effect size=0.40, 95% CI -0.23-0.102). Side effects were mild and the number of dropouts in the real TMS group was not significantly higher than in the sham group.
  
  
  CONCLUSIONS
  With the inclusion of studies with larger patient samples, the mean weighted effect size of rTMS directed at the left temporoparietal area for AVH has decreased, although the effect is still significant. The duration of the effect of rTMS may be less than one month. More research is needed in order to optimize parameters and further evaluate the clinical relevance of this intervention.
authors.affiliation: Parnassia Bavo Psychiatric Institute, Lijnbaan 4, 2512 VA The Hague, The Netherlands. c.slotema@psyq.nl
authors.forename: C W
authors.initials: CW
authors.lastname: Slotema
authors.forename: A
authors.initials: A
authors.lastname: Aleman
authors.forename: Z J
authors.initials: ZJ
authors.lastname: Daskalakis
authors.forename: I E
authors.initials: IE
authors.lastname: Sommer
mesh_terms: D001921:Brain / Q000502:physiology; D016208:Databases, Factual / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D006212:Hallucinations / Q000628:therapy*; D006801:Humans; D008297:Male; D015337:Multicenter Studies as Topic; D016032:Randomized Controlled Trials as Topic; D012189:Retrospective Studies; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D016896:Treatment Outcome