Transcranial Magnetic Stimulation in Neuropsychiatry
The 20th century saw two major revolutions in the somatic treatment of psychiatric disorder. First, ECT, which was developed in the 1930s, was shown to be effective in treating mood disorders in the 1940s. ECT remains the single most effective treatment for moderate to severe mood disorder. Second was the pharmacological revolution of the 1950s. It led to the development of a number of agents to treat schizophrenia, the anxiety disorders, and the mood disorders. Their effectiveness has been confirmed in numerous studies over the past half century.
The dawn of the 21st century has seen the emergence of two new potential somatic treatments for psychiatric illness, vagus nerve stimulation and transcranial magnetic stimulation, the subject of the book under review. This edited volume provides an excellent introduction for students, clinicians, and researchers wanting to learn about transcranial magnetic stimulation. It begins with chapters reviewing the history and physics of the procedure that are informative and accessible to readers who have no expertise in electrophysiology and provide an appreciation of the methodologic limitations of the current technology. The remainder of the book comprehensively reviews studies done through 1999 using transcranial magnetic stimulation as a probe to understand basic brain neurophysiology and as a therapeutic agent. Although more data need to be accumulated, the evidence reviewed in this book supports the safety of this procedure as a technique for examining brain function, particularly for briefly interrupting the function of specific brain regions but also as a probe for examining neural plasticity and connectivity.
Clinical studies done to date suggest that transcranial magnetic stimulation may have efficacy in treating mania and depression, but they also demonstrate that it will not help patients with idiopathic movement disorders or stuttering. However, follow-up studies and comparisons with existing therapies (pharmacological and ECT) are needed before conclusions can be made about its comparative efficacy.
A major strength of this volume is that most chapters clearly lay out the limitations of the work done to date. Many of the studies have been small, some are uncontrolled, and no large randomized, controlled trials have been reported. What is striking from these chapters is that the study of transcranial magnetic stimulation is developing in a rational, scientific manner with very few unsubstantiated claims. Its potential applications as a basic research tool and as a clinical therapeutic tool are exciting, but it is too early to determine if it will enter the clinical armamentarium or become a valid method of studying brain function. This volume is an excellent introduction to its potential uses and to the research that needs to be done before it is made widely available for either clinical or research practice.
