There is significant evidence that
transcranial magnetic stimulation (TMS) is effective in treating
severely depressed patients, a new study has found.
TMS involves the application of a dynamic
magnetic field to the scalp in order to induce electrical activity
in the underlying cortex of the brain. A coil of wire, encased in
plastic, is held to the head. A rapidly changing current flows in
its windings. This produces a magnetic field. The magnetic field
passes through the skin and skull. This induces current in the
brain. The current induced in the structure of the brain activates
nearby nerve cells in much the same way as currents applied
directly to the cortical surface.
Some studies support the potential of TMS as a
treatment for severe depression, whilst others have found little or
no benefit. Although the National Institute for Health and Clinical
Excellence (NICE) guidelines (2007) were uncertain about the
effectiveness of TMS, they recommended that further research is
undertaken to identify the patient selection criteria, the best use
of the procedure, and the duration of treatment effect.
The aim of this study was to examine the
effectiveness of TMS for patients suffering from severe
depression.
In 2003, the 5 Boroughs Partnership NHS Trust
established the first UK clinical TMS service. Patients meeting the
referral criteria received at least 120% of the motor threshold.
The Motor Threshold is the minimum dosage of stimuli required to
stimulate the motor cortex.
All the clinical symptoms of depression and
anxiety were measured, using established rating scales, before
treatment and after every five treatments. A cognitive examination
was carried out before the study began and again at the end of
treatment.
In total there were 135 referrals to the TMS
service. Assessments were completed on 115 of them. 17 referrals
were declined, as they were inappropriate.
Of the remaining 98 patients, 76 received full
treatment and 22 could not complete the course of treatment. 49
patients (50%) showed a 50% reduction in symptoms of
depression.
Of those who responded to TMS, 66% were female
and 33% male.
The researchers conclude that TMS is effective
in treating severe depression. Many technical details, such as the
site of stimulation, stimulus frequency, the total number of
stimuli and the duration of the treatment, need to be further
refined.
Further studies should be undertaken to
validate the treatment effect and duration and the durability of
the results, and also to further define the best stimulation
parameters.
Repetitive TMS clearly has physiological
effects on the brain, an observation that is remarkable in itself.
It may well be that the technology has potential therapeutic
effects in a range of psychiatric disorders that involve brain
neurons.
It is important, say the researchers, that the
challenges of this technology are overcome, in order to pursue the
potential clinical benefits of TMS for patients with mental health
problems.
For further information, please contact Liz Fox or Deborah
Hart in the Communications Department.
Telephone: 020 7235 2351 Extensions. 6298 or 6127
References:
Royal College of Psychiatrists’ Annual Meeting, Imperial College, London, 1 - 4 July 2008