Introduction 1994 1998 1991 2002 1994 2000 2004 2001 Method Participants n n Instruments 1966 For classification of PDDNOS, the minimal amount of positive DSM-IV criteria was two, of which at least one derived from the social interaction domain. For Asperger’s Disorder at least two items on the social domain and at least one item on the stereotypic domain needed to be present with no early delay of language. For High Functioning Autism at least six items were needed to be present, with at least two items on the social domain and at least one positive item on each of the other two domains, with onset of abnormal functioning before the age of three years. The reliability of the diagnostic protocol was tested by assessing a series of seven patients simultaneously by two experienced (child) psychiatrists (CK and EH). These independent classifications differed only on one patient (PDDNOS versus non-ASD). The seven patients were not included in the present study, which started after having determined diagnostic reliability. 2001 1996 1992 1994 Statistical Analysis Chi-square tests and analyses of variance were conducted to analyze possible differences between the groups. Results Fifteen of the 36 patients were diagnosed with ASD. In this ASD-group, 10 patients classified as PDDNOS, 4 patients as Asperger’s Disorder and 1 patient as High Functioning Autism. The number of positive DSM-IV items ranged from 2 to 8, with an average score of 3.8. 1 Table 1 Characteristics of participants Diagnosis n n n a m f m f m f b 22 years (18–24, 5) 27 years (18–55, 9) 35 years (14–73, 11) Mean IQ (sd) 104 (10) 105 (12)  a  p p b  p p 2 n n n Table 2 Mean scores AQ-D (sd) and ANOVA tests for differences in mean scores  n n n Social skill 5.0 (2.8) 4.2 (2.6) 4.1 (2.6) Attention switching 5.1 (2.6) 5.3 (2.4)  5.3 (2.3)  Attention to detail 3.5 (2.3) 4.4 (2.2) 4.2 (2.3) Communication* 4.5 (2.1) 3.5 (2.2) 2.8 (1.8) Imagination 4.4 (2.4) 4.3 (2.0) 3.5 (1.9) Total 22.5 (8.4) 21.8 (7.6) 19.9 (7.0) p 3 Table 3 SCAN-derived actual (past month) DSM IV Axis I diagnoses  N  n N  n No disorder 7 (47) 7 (33) Mood disorder with psychotic symptoms 2 (13) – Mood disorder without psychotic symptoms 2 (13) 3 (14) Substance abuse  3 (20) 2 (10) Sleep disorders 4 (27) 6 (29) Psychotic disorder NOS – 4 (19)* Schizophrenia – – Social Phobia 3 (20) 4 (19) Panic attacks/Agoraphobia 2 (13) 1 (5) Other anxiety disorders 1 (7) – Obsessive compulsive disorders 1 (7) 1 (5) Other disorders 1 (7) 2 (10) p 4 4 Table 4 IPDE derived Axis II diagnoses by ASD status  N N  n  n  n  n Paranoïd – – – 1 (5) Schizoïd  1 (7) 2 (13) 1 (5) 1 (5) Schizotypical – 1 (7) – – Antisocial – 1 (7) – – Borderline  1 (7) – – 1 (5) Avoidant  1 (7) 1 (7) 2 (10) – Obsessive compulsive – – 3 (14) 1 (5) Personality disorder NOS 1 (7) 2 (13) 3 (14) 1 (5) Any personality disorder 3 (20) 6 (40) 8 (38) 3 (14) Any personality disorder partial or complete 7 (47) 10 (48) Discussion 2001 2001 2001 2003 2005 . 2004 2001 2005 2005 There are important limitations to this study, among which is the small number of patients in the ATN-referred group. This major drawback precludes any definite conclusions. Of note is further that the ASD patients in this investigation belonged to the less-severe side of the spectrum. This makes it difficult to compare results with the investigations by Baron-Cohen and collegues. Clinical experience indicates that ASD patients, compared to non-ASD patients, benefit more from treatment by structuring, long-term repetitive treatment, and adaptations of the environment. This may hold even more when comorbid conditions are present. Since the prevalence of patients with less severe ASD is relatively high compared to the more severe ASD categories, efficient and valid screening of this group and charting possible comorbidity is consequently an even more important issue. The present study provided a modest contribution in improving our knowledge in this direction; clearly, much more research is needed.