Can damage to the brain, caused by emotional neglect during the first three years, be repaired later in life?

It is possible, but usually requires very specialist and expensive work over considerable time. The treatment is mainly behavioural i.e. getting people to learn how to behave differently. There is now increasing awareness that investing in the earliest years of children’s lives and ensuring that they receive responsive, consistent loving care yields the greatest return for society. 

For every £1 invested in the early years, a saving of £10 is made later in the cost to society of coping with issues such as crime, mental illness, and physical illness (Heckman, 2008). See diagram below.