Agitation-increased electromyogram activity in the corrugator muscle region: a possible explanation of the "Omega sign"?

The corrugator muscle region of the forehead has special significance in producing facial expressions associated with depression. Darwin observed in 1872 that contractions in the corrugator region produce peculiarly formed wrinkles on the forehead, referred to as "Omega Melancholium." In the present study, results from 61 right-handed, drug-free women with major depressive disorder showed a significant positive correlation between facial corrugator EMG values and psychomotor agitation. Results were not due to differences in severity of depression. These data offer preliminary evidence that agitation is reflected in corrugator muscle activity and may explain the "Omega sign" of melancholia.