Children with attention-deficit/hyperactivity disorder (ADHD) may not be able to smell as well as their peers, and researchers say that olfactory function might be a useful biological marker for early diagnosis, treatment, and prognosis of ADHD. Researchers at the Research Center for Psychiatry and Behavioral Sciences at the Shiraz University of Medical Sciences in Iran published in the June Psychiatry Investigation the results of their study of 50 participants aged 8 to 15 with ADHD who were compared with 50 controls. The two groups were matched for age, gender, and Mean School Scores (MSS). They assessed odor identification and threshold through a smell test composed of two tests of identification and detection threshold. Odor identification was assessed using chemical essences of five common odorants.The mean Sensory Identification Score for children with ADHD and for the control group was 3.76 and 4.46, respectively. The mean for Sensory Threshold Score for the ADHD subjects and for the control group was 6.4 and 9.75, respectively. The researchers said their results do not seem to be a result of olfactory task difficulty and were not influenced by age, gender, or MSS.Recent research has also identified rare genetic variations in children with ADHD that may help identify children at risk for developing the disorder. Read more about those findings in Psychiatric News, here. (image: n Goldswain/Shutterstock.com)