The age at which a girl starts menstruation does not appear to be associated with the age at which she develops schizophrenia. However, it may be linked to the severity of symptoms, researchers have found.

Writing in the journal Schizophrenia Research, the team, led by Dr Karen Hochman, from Emory University School of Medicine in Atlanta, Georgia, USA, explain that according to the “oestrogen hypothesis”, this hormone may serve as a protective factor in the development of schizophrenia.

Therefore, an earlier onset of puberty may be related to later onset of the illness in females.

To investigate, the team studied 68 women with either schizophrenia or schizoaffective disorder. Information on the age the women first began menstruating (menarche), and the onset and severity of their illness was collected.

They found that the age at menarche and the time at which schizophrenia began to develop were not associated, contrary to that implied by the oestrogen hypothesis.

However, menarche at an early age did seem to be linked to less severe schizophrenia symptoms, with women who reported a later age at menarche having higher negative symptom scores and greater functional impairment.

“This study suggests that an earlier age at menarche might predict improved clinical outcome after schizophrenia onset,” the researchers conclude.

However, they add further research is needed into the relationship between oestrogen and schizophrenia development in women.