An earlier-than-usual onset of puberty could be related with a higher chance of mental health issues, with incidence of depression and ADHD remaining high for at least eight years following onset, a study has found.

'Central precocious puberty' is a condition in which physical changes associated with this stage of growth begin early -- before age eight for girls, nine for boys.

Researchers, including those from University Hospital Essen, Germany, looked at over 6,500 individuals -- around 1,100 who had early puberty and the rest who did not -- using the country's health insurance data, following them for 13 years.