58 59 60 1 25 Page 1 of 30 1 2 3 Social relationship difficulties in autism and reactive attachment disorder; improving 4 5 diagnostic validity through structured assessment 6 7 8 Claire Davidson 1 ; Anne O’Hare 2 , Fiona Mactaggart 3 , Jonathan Green 4 , David Young 5 , 9 10 Christopher Gillberg 1&6 and Helen Minnis 1 11 12 13 1 Institute of Health and Wellbeing, University of Glasgow, Glasgow, UK; 2 Department of 14 15 16 Child Life and Health, University of Edinburgh, Edinburgh, UK; 3 Edinburgh Connect and 17 18 North Edinburgh Team, Child and Adolescent Mental Health Service, North Edinburgh team, 19 20 Edinburgh, UK; 4 Institute of Brain, Behaviour and Mental Health, University of Manchester, 21 22 Manchester, UK; 5 Department of Mathematics and Statistics, Strathclyde University, 23 24 Glasgow, UK; 6 Gillberg Neuropsychiatry Centre, University of Gothenburg, Gothenburg, 26 27 Sweden. 28 29 30 Words: 5999 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57