New research has found more than a third of children don’t play outdoors after school and one in five don’t at weekends, raising concerns about children’s physical and mental health.

Immune cells released from bone marrow in the skull in response to chronic stress and adversity could play a key role in symptoms of depression and anxiety, say researchers. The discovery – found in a study in mice – sheds light on the role that inflammation can play in mood disorders and could help in the search for new treatments, in particular for those individuals for whom current treatments are ineffective.