BACKGROUND: The clinical profiles of youth presenting to early intervention mental health services are heterogeneous, with various sub-groups proposed and little information about the longitudinal stability of profiles especially those associated with bipolarity. METHODS: 802 youth aged 12-25-years (Mean = 18.26
66 % females) accessing primary-care based mental health clinics were assessed at baseline and 417 were re-assessed after 12-months. An exploratory factor analysis of 62 items from six validated rating scales of the severity of mental and physical ill-health scale items was conducted. Seven factors (anxiety, sleep, depression, restlessness, distress, activation, somatic complaints) were derived and modelled using latent profile analysis. Associations between profile membership, clinical outcomes and functioning were examined. Conditional probabilities of shifting to a different profile longitudinally were computed. RESULTS: Three profiles were revealed which were psychometrically invariant across baseline and follow-up: (1) 'High distress with high activation' (32 % baseline, 25 % follow-up)
(2) 'High distress without activation' (31 % baseline, 26 % follow-up)
and (3) 'Moderate distress' (37 % baseline, 33 % follow-up). A fourth profile, 'Low distress' (16 %), emerged at follow-up. Profiles did not differ by age or sex. 'High distress with high activation' was more likely to be impaired longitudinally, and more likely to meet criteria for a full-threshold mental disorder at follow-up. About 39 % of youth retained the same profile longitudinally, while 16 % shifted to lower, and 13 % shifted to higher distress. CONCLUSION: These findings suggest that activation is a marker of poorer clinical and functional outcomes in youth presenting for mental health care.