However, the study, to be published in the Journal of Child Psychology and Psychiatry in November, found no increase in fighting, bullying or other aggressive behaviour. The research, carried out by the Institute of Psychiatry, King's College London, and the University of Manchester, looked at three generations of 15-year-olds, in 1974, 1986 and 1999. Behavioural problems increased over the entire period while emotional problems were stable until 1986, after which they increased dramatically.