Positive Emotions from Brain Injury: The Emergence of Mirth and Happiness

Abstract

Brain injury can result in an increase in positive emotions. We describe a 63-year-old man who presented with a prominent personality change after a gunshot wound to the head. He became "content," light-hearted, and prone to joking and punning. Prior to his brain injury, he suffered from frequent depression and suicidal ideation, which subsequently resolved. Examination showed a large right calvarial defect and right facial weakness, along with memory impairment and variable executive functions. Further testing was notable for excellent performance on joke comprehension, good facial emotional recognition, adequate Theory of Mind, and elevated happiness. Neuroimaging revealed loss of much of the right frontal and right anterior lobes and left orbitofrontal injury. This patient, and the literature, suggests that frontal predominant injury can facilitate the emergence of mirth along with a sense of increased happiness possibly from disinhibited activation of the subcortical reward/pleasure centers of the ventral striatal limbic area.

Figure 1

Corresponding axial computerized tomography (CT), magnetic resonance imaging (MRI; fluid-attenuated inversion recovery), and fluorodeoxyglucose positron emission tomography (FDG-PET) scans of the brain. (a) CT shows a large right frontal calvarial vault defect with underlying extensive volume loss/encephalomalacia in the right frontal and anterior right temporal lobes with surrounding gliosis. There is also volume loss and gliosis at the anteroinferior aspect of the left frontal lobe. (b) MRI corroborates the CT findings in a greater detail. (c) FDG-PET shows hypometabolism of right frontal, anterior right temporal, and left anterior inferior frontal lobes corresponding to the CT and MRI findings.