Abstract
BACKGROUND: So far, little is known about the comorbidity of substance use disorders (<span class="abbreviation">sud</span>) and autism spectrum disorders (<span class="abbreviation">asd</span>). AIM: To increase our knowledge of <span class="abbreviation">sud</span> in <span class="abbreviation">asd</span> patients by means of a broad explorative study. METHOD: In a cross-sectional study 70 patients with <span class="abbreviation">asd</span> were compared with 53 patients with <span class="abbreviation">adhd</span>. Both groups included some patients with <span class="abbreviation">sud</span> and without <span class="abbreviation">sud</span>. Comparisons were drawn at three different levels: phenotype, endophenotype and genotype. RESULTS: At the phenotypical level, risk factors for <span class="abbreviation">sud</span> were similar for <span class="abbreviation">asd</span> and <span class="abbreviation">adhd</span> (early onset smoking, adverse family history, parental addiction). The subgroup <span class="abbreviation">asd</span>-with-<span class="abbreviation">sud</span> reported better social orientation than the subgroup <span class="abbreviation">asd</span> -without - <span class="abbreviation">sud</span>, in spite of having impaired functioning at the phenotypical level and more cognitive problems at the endophenotypical level. At the genetic level, <span class="abbreviation">asd</span> could be differentiated from <span class="abbreviation">adhd</span> on the basis of three candidate genes, but this differentiation was irrespective of <span class="abbreviation">sud</span> status. CONCLUSION: <span class="abbreviation">sud</span> occur less frequently with <span class="abbreviation">asd</span> than with <span class="abbreviation">adhd</span>, but when they occur, they are just as severe. These results have implications for treatment.
