Apathy and depressed mood in acquired brain damage: relationship to lesionlocalization and psychophysiological reactivity

Background. Apathy is a frequent neurobehavioural sequel in patients with a cquired brain damage and it may seriously affect outcome of rehabilitation. Methods. Patients with traumatic brain injury, cerebrovascular insults and hypoxic brain injury, categorized into four lesion localization groups: lef t hemisphere damage (LHD); right hemisphere damage (RHD); bilateral hemisph eric damage (BHD); and subcortical damage (SCD) were assessed with the Apat hy Evaluation Scale (AES) and Montgomery and Asberg Depression Rating Scale (MADRS). Heart rate and electrodermal activity were recorded in an experim ental situation that exposed the patients to mental stressors in order to m easure psychophysiological reactivity. Results. Significant differences in level of apathy were found between diag nostic groups as well as between localization subgroups. SCD and RHD patien ts displayed most apathy. Factor analysis of MADRS revealed a three-factor solution; depressed mead, somatic symptoms and negative symptoms. Apathy wa s significantly correlated with negative symptoms in all localization subgr oups, except among the BHD patients. Apathy was not correlated with depress ed mood or somatic symptoms. Moreover, apathy was significantly correlated with heart rate reactivity, but not with electrodermal reactivity. Conclusion. Apathy is common, its severity depending on diagnosis and local ization of lesion. Apathy and depression in brain damaged patients share co mmon features, but may be differentiated. The significant relationship betw een apathy and heart rate may provide a psychophysiological correlation of the disengagement, lack of interest and absence of emotional responsivity t ypically seen in apathy. The results have implications for the theoretical understanding of apathy and related negative symptoms, and for rehabilitati on practice.