When young children experience separation from a parent or important family member, adoption, abuse, maternal depression or anxiety, premature birth, trauma such as a natural disaster or accident, or have a serious illness or medically-diagnosed physiological or developmental disorder, they can struggle just like adults and older kids too, but it may be less noticeable.

Infants and children ages 0 to 5 can experience emotional/mental withdrawal, hypervigiliance, severe distress, resistance to daily functioning and routines, or demonstrate negative/aggressive behavior. Such children can benefit from doing "dyadic therapy", therapy in which a therapist works as a team with the parent (and even other family members) to assess non-verbal or verbal behavior and cues and assist positive transformation in the way the child relates to family members and others.