This report finds that a head injury doubles a person’s risk of later mental health problems, even if the person had no prior history of mental ill-health. Around 1.3 million people in the UK are living with head injury-related disabilities, and these injuries cause around 160,000 hospital admissions each year. Traumatic brain injury also has a marked impact on the economy, at a cost of £15 billion a year. This figure comprises lost work contributions, premature death and health and social care costs. The £15 billion does not include the human costs of head injury on people’s wellbeing and quality of life, which is clearly the biggest cost.