Egeland J A, Blumenthal R L, Nee J, Sharpe L, Endicott J
J Affect Disord. 1987 Mar-Apr;12(2):159-65. doi: 10.1016/0165-0327(87)90009-7.
This paper presents data on six different clinical definitions (indices) of age of onset for major affective disorders. The inter-rater reliability for each index and the relationships among these indices are discussed. Age of onset for impairment with affective symptoms was found to be a reliable and useful index of early onset. It discriminated between unipolar depressed subjects and both bipolar I and bipolar II subjects.
