Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/11903
Accumulated research points to certain associations between substance use disorder (SUD) and attention-deficit/hyperactivity disorder (ADHD). The intent of this thesis was to examine associations between SUD and ADHD among Icelandic adults. In line with results of earlier studies, it was hypothesized that individuals with ADHD are diagnosed with SUD at an earlier age and show shorter times of abstinence than individuals without ADHD. A positive correlation was predicted between age at offset of stimulant medication for ADHD and age at diagnosis of SUD. No associations were predicted between ADHD diagnosis and specific SUDs (i.e. specific substances of abuse) or between diagnosis of ADHD subtype and specific SUDs. The study was retrospective and used data from a large-scale study on the genetics of SUD. Data of 931 individuals (643 men and 288 women) who had been diagnosed with SUD were analyzed, including 58 individuals with ADHD. Individuals with ADHD were diagnosed with SUD at an earlier age than individuals without ADHD and showed shorter times of abstinence from stimulants, but not from alcohol, cannabis, cocaine, opiods and sedatives. The relationship between age at offset of stimulant medication and age at onset of SUD was not tested since data about ADHD medication were available for very few individuals. Individuals with ADHD were more likely to be diagnosed with amphetamine, cannabis, cocaine and sedatives use disorder than individuals without ADHD, but there were no association between ADHD diagnosis and alcohol and opiod use disorder. However, individuals with ADHD were diagnosed with more SUDs than individuals without ADHD. No associations were found between diagnosis of ADHD subtypes and specific SUDs.