The neurocognitive phenotype of apathy following acquired brain damage

Apathy is one of the most common neuropsychiatric sequelae of acquired brain damage. The disorder is usually defined in terms of observed deficits in motivation related behavioural, emotional, and cognitive aspects of goal directed activity. Most neuropsychological research on apathy has focused primarily on its associated neurocognitive correlates; particularly those related to executive dysfunction, or its association with other clinical syndromes like depression. Results from these studies have been mixed, probably reflecting the use of different neuropsychiatric samples and assessment tools, or reflecting the differences in the conceptualisation of apathy across studies. In this study we ask whether performance on 'standard' executive tests would distinguish brain-damaged patients with apathy symptoms from those without apathy. To potentially strengthen the power of the possible relationships between apathy and executive function we included brain-injured patients with varied aetiologies, and used a much broader range of 'executive function' tests than in previous studies. Results indicate that the Tower of Hanoi puzzle is sensitive to apathy symptoms. Patients with apathy symptoms were significantly impaired on the task compared to non-apathetic patients. Performance on the Wisconsin Card Sorting test, the Hayling and Brixton tests, and the Stroop test failed to show this distinction. We discuss these findings and their implications for treatment and rehabilitation.