Indeed, most of us, as carers -- lay, family, or professional -- are not used to, or trained to, think in such terms. More's the pity. Only somewhat related to the topic -- in terms of overall childhood mental illness, and not adult, or physical illness, is the paper by Smith and Smith DOI: 10.1016/j.socscimed.2010.02.046
"Long-term economic costs of psychological problems during childhood"
Still pretty gobsmacking in its implications, especially when one considers people like van der Kolk call childhood trauma the #1 Public Health Problem (not just mental health problem -- understandably, when one considers the physical illnesses it's linked to).