Why is this review important?
Panic disorder is a common mental disorder and its lifetime prevalence is 5.1%. The major characteristic of panic disorder is the occurrence of unexpected panic attacks with consequent anxiety about experiencing another attack. Despite major advances in the treatment, many people with panic disorder do not respond well to either medication or psychological therapy. In recent years, an association was found between panic symptoms and increased activity in the right frontal region of the brain. Repetitive transcranial magnetic stimulation (rTMS) is a new technique for the stimulation of the central nervous system. It works through placing an electromagnetic coil against the scalp, which generates a rapidly changing magnetic field to induce localised electrical currents. Low frequency rTMS can reduce this increased activity in the brain and so rTMS is emerging as a new way to treat people with panic disorder. Some studies have investigated the effect of rTMS on patients with PD and observed a reduction in anxiety levels. The aim of this review was to combine the results of all the randomised controlled trials of rTMS for panic disorder to investigate the effectiveness and safety of this treatment.
Who will be interested in this review?
People affected by panic disorder.
General practitioners (GPs).
Professionals working in adult mental health services.
Families and friends of people who suffer from major depression.
What questions does this review aim to answer?
Is rTMS effective in treating adults with panic disorder, either on its own or in combination with other treatments?
Which studies were included in the review?
We searched for all the relevant studies on rTMS for panic disorder in people aged 18 to 65 years. Our search found only two studies which met our inclusion criteria and they were included in this review. Information about the way that the studies were conducted were not very well detailed and for one study there was a large proportion of people whose data were not incorporated in to the analysis.
The two studies involved a total of 40 people with panic disorder and reported the effect of rTMS on panic symptoms after two or four weeks of rTMS. Both studies used low-frequency rTMS which lasted 30 minutes and was applied to a region of the brain called the right prefrontal site. Most participants were also taking antidepressant drugs or receiving psychological therapy. No studies compared the differences between rTMS and any other therapy, such as medication, psychological therapy and electroconvulsive therapy (ECT).
What does the evidence from the review tell us?
One study found that all patients improved during the study period, but the treatment effect did not differ between the group who received rTMS and the group who received sham rTMS. The other study administered more sessions and reported higher levels of improvement of panic symptoms in those people who received rTMS compared to those who received sham rTMS.
Although neither trial reported any serious side effects, they provided only very low quality evidence for adverse event outcomes. On the basis of the limited quality of the evidence available we were unable to determine how safe rTMS is.
The limited information available from these two studies is insufficient to conclude whether rTMS is effective in reducing the severity of panic disorder symptoms. The main limitation of this review was that the number of people with panic disorder who were involved was too small.
What should happen next?
To find out more about rTMS for panic disorder, there is a need for more studies to be carried out which involve larger numbers of people and compare sham rTMS with real rTMS.
Only two RCTs of rTMS were available and their sample sizes were small. The available data were insufficient for us to draw any conclusions about the efficacy of rTMS for PD. Further trials with large sample sizes and adequate methodology are needed to confirm the effectiveness of rTMS for PD.
Panic disorder (PD) is a common type of anxiety disorder, characterized by unexpected and repeated panic attacks or fear of future panic attacks, or both. Individuals with PD are often resistant to pharmacological or psychological treatments and this can lead to the disorder becoming a chronic and disabling illness. Repetitive transcranial magnetic stimulation (rTMS) can deliver sustained and spatially selective current to suppress or induce cortical excitability, and its therapeutic effect on pathological neuronal activity in people with PD has already been examined in case studies and clinical trials. However, a systematic review is necessary to assess the efficacy and safety of rTMS for PD.
To assess the effects of repetitive transcranial magnetic stimulation (rTMS) for panic disorder (PD) in adults aged 18 to 65 years, either as a monotherapy or as an augmentation strategy.
An electronic search of the Cochrane Depression, Anxiety and Neurosis Review Group Controlled Trials Register (CCDANCTR) was conducted to 19 February 2014. The CCDANCTR includes reports of relevant randomised controlled trials (RCTs) from MEDLINE (1950 to date), EMBASE (1974 to date), PsycINFO (1967 to date) and the Cochrane Central Register of Controlled Trials (CENTRAL) (all years). Additional searches were conducted in Psyndex and the main Chinese medical databases.
RCTs or quasi-randomised trials evaluating rTMS for PD in people aged between 18 and 65 years, either as a monotherapy or as an augmentation strategy.
Two review authors independently selected studies and extracted data and verified the data by cross-checking. Disagreements were resolved by discussion. For binary data, we calculated fixed-effect model risk ratio (RR) and its 95% confidence interval (CI). For continuous data, we calculated fixed-effect model standardized mean difference (SMD) and its 95% CI.
Two RCTs (n = 40) were included in this review. The included trials compared rTMS with sham rTMS; no trials comparing rTMS with active treatments (electroconvulsive therapy (ECT), pharmacotherapy, psychotherapy) met our inclusion criteria. Both included studies used 1 Hz rTMS over the right dorso-lateral prefrontal cortex (DLPFC) for two or four weeks as an augmentation treatment for PD. However, in both studies the data for the primary outcome, panic symptoms as measured by the Panic Disorder Severity Scale (PDSS), were skewed and could not be pooled for a quantitative analysis. For this primary outcome one trial with 25 participants reported a superior effect of rTMS in reducing panic symptoms compared with sham rTMS (t = 3.04, df = 16.57, P = 0.007), but this trial had a 16% dropout rate and so was deemed as having a high risk of attrition bias. The other trial found that all 15 participants exhibited a reduction in panic symptoms but there was no significant difference between rTMS and sham rTMS (Mann Whitney U test, P > 0.05). Regarding the acceptability of rTMS, no significant difference was found between rTMS and sham rTMS in dropout rates or in reports of side effects. The quality of evidence contributing to this review was assessed as very low. Assessments of the risk of bias for the two studies were hampered by the lack of information provided in the reports, especially on methods of sequence generation and whether allocation concealment had been applied. Of the remaining sources of bias, we considered one of the studies to have been at risk of attrition bias.