Electroconvulsive therapy (ECT) can improve therapeutic outcomes in some patients with mood disorders who are not responsive to antidepressant drugs, but it is controversial because of its apparently unspecific effect. A new study shows that in patients with unipolar or bipolar disorder, ECT has highly specific, spatially distributed effects on local brain volume in regions implicated in these disorders. Interestingly, the degree of brain-volume change correlates with the therapeutic effectiveness of ECT.