A Biopsychosocial Framework for Apathy Following Moderate to Severe Traumatic Brain Injury: A Systematic Review and Meta-analysis.

Apathy, the deficit of goal-directed behaviour, is well recognised as one of the most debilitating syndromes after moderate-to-severe traumatic brain injury (TBI). However, mechanisms underlying apathy, or at least factors associated with apathy, are sporadically reported. Based on a biopsychosocial framework, this systematic review and meta-analysis synthesised evidence regarding neurobiological, socio-environmental and individual factors associated with apathy. Our searches identified 21 studies satisfying inclusion and exclusion criteria. Results showed that the majority of work has focused on cognitive dysfunction, TBI-related factors, demographic variables and psychological correlates of apathy, while evidence for neural substrates and socio-cultural and premorbid aspects is scant. Overall, the current literature suggests that TBI-related and patient demographic factors did not contribute to apathy after TBI, whereas complex neurocognitive alterations, socio-environmental and cultural factors as well as patients' self-related factors may be important components. The evidence points to the multifaceted interplay of certain biopsychosocial contributors to apathy and suggests future investigations of more complex behavioural traits, cultural elements and pre-injury levels to better characterise the aetiology of this detrimental impairment after TBI.