Economic case for prevention
In 2017 Public Health England launched a groundbreaking new tool for local public health teams identifying the most cost-effective mental health programmes. One of these eight initiatives is an innovative resilience programme in schools that results in an estimated saving of £5.08 for every £1 invested (over three years).
Though Workplace focused, the Deloitte Paper from the Stevenson-Farmer Independent Review into Mental Health in the workplace, it is a superb model. The cost of poor mental health in the workplace is a significant number at £33bn-£42bn; the mid-point of which is equivalent to almost 2% of UK GDP (2016). This cost is borne by businesses of all sizes and across all industries, with analysis showing the costs per employee ranging from £497 – £2564, depending on the industry and sector. The research found that the return on investment of workplace mental health interventions is overwhelmingly positive, with an average ROI of 4:1. https://www2.deloitte.com/uk/en/pages/public-sector/articles/mental-health-employers-review.html
The best comprehensive summary of the evidence and prevalence of mental health issues is to be found in last Decembers ‘Transforming children and young people’s mental health provision: a green paper’ Pages 6-9, Chapter 1 - Case for action: the evidence. https://www.gov.uk/government/consultations/transforming-children-and-young-peoples-mental-health-provision-a-green-paper
Finally, the £105 billion a year reference is the PDF 'The Five Year Forward View for Mental Health - NHS England - Executive Summary.' "Mental health problems represent the largest single cause of disability in the UK. The cost to the economy is estimated at £105 billion a year – roughly the cost of the entire NHS". https://www.england.nhs.uk/wp-content/uploads/2016/02/Mental-Health-Taskforce-FYFV-final.pdf