Children and young people’s mental health: the evidence Mental health problems are common among young people (affecting one in ten, or an average three in every classroom). On average, children and young people with mental health difficulties go ten years between first becoming unwell and getting any help, according to our recent evidence review. This decade of delay sees their problems multiply and get progressively worse, eventually escalating into a crisis. Moreover, whilst three-quarters of parents whose children are experiencing a mental health difficulty seek help, only one-quarter receive any support. 0-4 years Good mental health, wellbeing and cognitive development in under five year olds is shaped very early on from the first spark of life in the womb and is affected by multiple complex genetic and environmental factors. Sensitive parenting by both mother and father, as well as healthy attachment, act as important buffers against stress, enabling babies to learn to self-soothe. Parental praise and warmth are associated with children having higher self-esteem, higher social and academic competences, and reduced likelihood of disruptive behaviour and future substance misuse. Infants and toddlers facing the highest risks for poor mental health include those whose parents have mental health problems or misuse substances, those who are subject to maltreatment and neglect, and those who live in prolonged poverty. There is a range of interventions that can help to protect a child’s mental health from pregnancy to age five. Most need to be targeted towards families who have the highest risks, or children who are showing early signs of distress. They include group parenting programmes for children with behavioural problems; home visiting programmes for parents facing high risks (such as Family Nurse Partnerships); and effective, timely treatment for maternal mental ill health. 5-10 years Schools are the biggest single influence on a child’s mental health after their family. Schools can either enhance or undermine a child’s mental health and it is essential they know how to help. Around 8% of children will have a diagnosable mental health problem during middle childhood.The most common difficulty is conduct disorder, and at this stage, boys are twice as likely as girls to have a diagnosable mental health difficulty. Studies show that children who have been bullied have higher prevalence of poor mental health and face a range of other adverse outcomes across their life. A ‘whole school approach’ to mental health has the best chance of supporting children’s wellbeing and their future educational attainment and life chances. 11-15 years Adolescence is a period of significant neurodevelopmental change for most children. While adolescence and early adulthood are a period of our best physical health, it is also the peak period for the development of mental health problems. During secondary school, one child in eight will have one or more mental health conditions at any time. Boys are more likely to present with behavioural problems whereas girls are more likely to have emotional problems. Self-harm is relatively common, especially among girls, LGBT young people and children with a diagnosable mental health problem. Some studies have found rising levels of emotional problems in this age group among girls. Young people in this age group largely don’t know where to get help for emotional problems, and feel stigma strongly. Many favour informal sources of support such as friends and family. 16-25 years 75% of adults with a diagnosable mental health problem will have experienced their first symptoms by the age of 24. Evidence shows that common mental health conditions that first emerge in adolescence have a higher chance of persistence into young adult years if not quickly treated and contained. At any one time, around 20% of young people in this age band are experiencing a diagnosable mental illness. 60% of disability experienced by those aged 15-34 years is caused by mental health problems. It therefore represents a major burden of disease for this age group and should be a health improvement priority. 13% of men and 22% of women in this age group reported suicidal thoughts This age band is the peak period for the first onset of psychosis For a more detailed overview of children and young people's mental health, see Missed opportunities, as well as the rest of our work on children.