Lowered sensitivity to facial emotions in myotonic dystrophy type 1

BackgroundIt has been observed that patients with myotonic dystrophy type 1 (DM1) exhibit social-cognitive impairment. However, the cognitive and neurological bases of the social-cognitive impairment in DM1 have not been adequately investigated.MethodsWe studied cognitive deficits and impairment in facial expression recognition in two DM1 patients (one man and one woman). We measured the sensitivity of these patients to basic emotions and compared the results with those from magnetic resonance imaging and single photon emission computed tomography.ResultsThe DM1 patients showed lower sensitivity to fearful, disgusted, and angry faces than did the healthy controls. They also had lesions in the anterior temporal white matter, the amygdala, and the insular and orbitofrontal cortices.ConclusionThe results of this study revealed that the DM1 patients had subcortical lesions in the anterior temporal areas, including the amygdala and the insular and orbitofrontal cortices. The limbic system, which includes these areas of the brain, plays an important role in emotional processing. Hence, the social-cognitive impairment in DM1 patients could be associated with a decreased sensitivity to facial expressions owing to lesions in the limbic system.