Anterior cingulate activity as a predictor of degree of treatment responsein major depression: Evidence from brain electrical tomography analysis

Objective: The anterior cingulate cortex has been implicated in depression. Results are best interpreted by considering anatomic and cytoarchitectonic subdivisions. Evidence suggests depression is characterized by hypoactivit y in the dorsal anterior cingulate, whereas hyperactivity in the rostral an terior cingulate is associated with good response to treatment. The authors tested the hypothesis that activity in the rostral anterior cingulate duri ng the depressed state has prognostic value for the degree of eventual resp onse to treatment. Whereas prior studies used hemodynamic imaging, this inv estigation used EEC. Method: The authors recorded 28-channel EEC data for 18 unmedicated patient s with major depression and 18 matched comparison subjects. Clinical outcom e was assessed after nortriptyline treatment. Of the 18 depressed patients, 16 were considered responders 4-6 months after initial assessment. A media n split was used to classify response, and the pretreatment EEG data of pat ients showing better (N=9) and worse (N=9) responses were analyzed with low -resolution electromagnetic tomography, a new method to compute three-dimen sional cortical current density for given EEG frequency bands according to a Talairach brain atlas. Results: The patients with better responses showed hyperactivity (higher th eta activity) in the rostral anterior cingulate (Brodmann's area 24/32). Fo llow-up analyses demonstrated the specificity of this finding, which was no t confounded by age or pretreatment depression severity. Conclusions: These results, based on electrophysiological imaging, not only support hemodynamic findings implicating activation of the anterior cingul ate as a predictor of response in depression, but they also suggest that di fferential activity in the rostral anterior cingulate is associated with gr adations of response.