One of the biggest myths about childhood depression (also known as pediatric depression) is that it doesn’t exist.

However, depression is a real illness that affects both adults and kids. In fact, kids as young as 3 years old can have depression.

Depression can even affect babies, who tend to exhibit symptoms such as unresponsiveness, lethargy, inconsolable crying and feeding problems, writes Deborah Serani, PsyD, a clinical psychologist who specializes in mood disorders, in her new book Depression and Your Child: A Guide for Parents and Caregivers.

Below, she revealed what pediatric depression looks like, along with what you can do if you spot these signs.