The Brisbane Lions have lost promising young defender Justin Clarke (pictured) after he announced his retirement on Thursday.
Clarkes premature departure from the game is sure to bring increased focus on the effects of concussion in sport in Australia after he failed to recover from the effects of a head knock he received at training in January.
Clarke has had significant and extended loss of memory since the knock and it was an emotional young man that fronted the media to bring an end to his 56 game career.
