Schizophrenia may be related to the deletion syndrome. However, not everyone who has the syndrome necessarily develops psychotic symptoms. What triggers the illness? Researchers (UNIGE) have provided an initial answer after analysing several years of patients with deletion syndrome. They found that the size of the hippocampus was smaller than normal but followed the same developmental curve as in healthy subjects. Yet, when the first psychotic symptoms appear – generally in adolescence – the hippocampus atrophies dramatically.