Deep brain stimulation for obsessive-compulsive disorder and treatment-resistant depression: systematic review

<p>Abstract</p> <p>Background</p> <p>In spite of advances in psychotherapy and pharmacotherapy, there are still a significant number of patients with depression and obsessive-compulsive disorder that are not aided by either intervention. Although still in the experimental stage, deep brain stimulation (DBS) offers many advantages over other physically-invasive procedures as a treatment for these psychiatric disorders. The purpose of this study is to systematically review reports on clinical trials of DBS for obsessive-compulsive disorder (OCD) and treatment-resistant depression (TRD). Locations for stimulation, success rates and effects of the stimulation on brain metabolism are noted when available. The first observation of the effects of DBS on OCD and TRD came in the course of using DBS to treat movement disorders. Reports of changes in OCD and depression during such studies are reviewed with particular attention to electrode locations and associated adverse events; although these reports were adventitious observations rather than planned. Subsequent studies have been guided by more precise theories of structures involved in DBS and OICD. This study suggests stimulation sites and prognostic indicators for DBS. We also briefly review tractography, a relatively new procedure that holds great promise for the further development of DBS.</p> <p>Methods</p> <p>Articles were retrieved from MEDLINE via PubMed. Relevant references in retrieved articles were followed up. We included all articles reporting on studies of patients selected for having OCD or TRD. Adequacy of the selected studies was evaluated by the Jadad scale. Evaluation criteria included: number of patients, use of recognized psychiatric rating scales, and use of brain blood flow measurements. Success rates classified as "improved" or "recovered" were recorded. Studies of DBS for movement disorders were included if they reported coincidental relief of depression or reduction in OCD. Most of the studies involved small numbers of subjects so individual studies were reviewed.</p> <p>Results</p> <p>While the number of cases was small, these were extremely treatment-resistant patients. While not everyone responded, about half the patients did show dramatic improvement. Associated adverse events were generally trivial in younger psychiatric patients but often severe in older movement disorder patients. The procedures differed from study to study, and the numbers of patients was usually too small to do meaningful statistics or make valid inferences as to who will respond to treatment.</p> <p>Conclusions</p> <p>DBS is considered a promising technique for OCD and TRD. Outstanding questions about patient selection and electrode placement can probably be resolved by (a) larger studies, (b) genetic studies and (c) imaging studies (MRI, fMRI, PET, and tractography).</p

Auditory Evoked Potential Variability in Schizophrenia

Variability of the individual brain wave potentials comprising an auditory averaged evoked potential (AEP) is greater for schizophrenic than for normal subjects. In schizophrenics this increased AEP variability results in fewer similarities, and therefore lowered correlations, between two AEPs evoked by tones of the same pitch. Thus, the increased difference between AEPs to tones of two different pitches found in schizophrenia seems to be a function of increased AEP variability. This increase of AEP variability in schizophrenic patients reflects response variability and is not principally the result of increased background EEG variability. AEP standard deviation is highly correlated with AEP amplitude, and methods of correcting for this are discussed

Auditory Evoked Potential Variability in Schizophrenia. II. The Application of Discriminant Analysis

The data recorded by Callaway et al. in a study of degree of dissimilarity of two-tone average evoked potentials (AEPs) in normal and schizophrenic patients were analyzed by the Step-Wise Discriminant Analysis (SWDA) technique. The analysis was undertaken to determine if (a) groups of single-trial records obtained with two dissimilar tones show a greater dispersion than groups of single-trial records obtained with identical tones, and (b) the degree to which the dissimilarity of two-tone AEPs, if found, is consistent between subjects (i.e., the same evoked potential components contribute to the dissimilarity in an equivalent manner). The application of this analysis to the two-tone AEPs demonstrates that although there is indeed a somewhat increased dissimilarity between the AEPs to dissimilar tones, there is no appreciable difference in this respect between schizophrenic and normal subjects. Furthermore, there is little consistency in the AEP components that differentiate the two AEPs from one subject to the next. The results of this analysis in conjunction with those reported in a companion paper by Callaway et al. (1970) suggest that the previously reported differences between normal and schizophrenic subjects are largely the result of the increased variability in the AEP of schizophrenics rather than of a consistent tendency of the patients to concentrate on trivial differences between the tones