When a child is born their brain already contains a finely sculpted network of brain cells connected in a predetermined pattern. This is achieved by balancing the rate of brain cell growth against cell death. To understand this researchers studied SORCS2, a gene that intriguingly has opposing roles in different parts of the brain. The product of this gene exists in two forms: a single long protein that regulates growth at the hand-like extremities (stained orange) of the pictured cell, and a composite of two linked segments of the protein which together control cell death. Mice lacking this gene exhibit traits very similar to attention deficit and hyperactivity disorder (ADHD) such as increased physical activity that is calmed by amphetamine drugs. Such a clear cut biological pathway – from gene to protein to cells to symptoms – suggests that disrupting the balance between brain cell growth and death underpins attention deficit disorders.
Written by Julie Webb