There was a time when ‘physical’ treatments in psychiatry implied electroconvulsive therapy (ECT) and psychosurgery, but during the past 20 years some alternatives have been developed. The aspirations are that the new treatments are less invasive or reversible, and result in fewer side-effects while being as efficacious.

Transcranial magnetic stimulation (TMS) is the best-known of these methods and there is a growing body of research trial data in depression and schizophrenia. It is thought to work by inducing subconvulsive electrical activity in brain areas of interest. Magnetic seizure therapy (MST) is a logical development of TMS and uses focal magnetic fields to induce seizures in the anaesthetised patient. The localised application and the use of magnetism rather than electricity are seen as possible benefits over ECT. Deep brain stimulation (DST) requires the implantation of electrodes in the brain area of interest which are connected by wires to a pulse generator implanted subcutaneously in the chest wall. In the field of psychiatry, DST has so far only been used to treat a handful of people with intractable obsessive-compulsive disorder. Vagus nerve stimulation (VNS) was first developed as a treatment for intractable epilepsy, but its use has now been studied in depression. Again, this involves the subcutaneous implantation of a pulse generator in the chest wall, linked to electrodes attached to the left vagus nerve in the neck. In both DST and VNS the frequency and amplitude of the current pulses can be varied externally by a magnetic wand.

The five reviews in this book cover the scientific background and rationale for each treatment and their clinical effectiveness in a variety of neuropsychiatric conditions. Adverse effects are discussed with admirable frankness. For TMS and MST, these include headache and the possible induction of spontaneous seizures. For the more invasive procedures, adverse effects are certainly more serious and more common: for DBS there is a reported infection rate of 25% and brain haemorrhage rate of 5%; for VNS, voice alteration, automatic coughing and neck pain are relatively common problems.

Some might view this area of clinical research as ‘blue skies’ and, as is made clear by the editor, each technology is in its infancy. None is currently approved by the US Food and Drug Administration for the treatment of mental illness. However, as ECT and psychosurgery are becoming more difficult to use in some parts of the world, these new methods may eventually offer practical alternatives for treating the most resistant disorders.