One of the most revealing findings is that only one in 20 of those who attend youth groups say they would discuss personal issues with a youth worker.
But evidence from drop-in centres showed as many as eight out of 10 were prepared to talk over sensitive matters with leaders. The study also highlights a lack of guidance and counselling within mainstream youth work.
Fully qualified youth workers had less contact with young people than other voluntary leaders, the researchers say.
Their report concludes: "Given that older youths encounter a greater range of risks (such as those associated with the use of drugs and alcohol and involvement in illegal activities), this is a serious shortcoming of the service."