Research Center for Psychiatry and Behavioral Sciences, Department of Psychiatry, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
Psychiatry Investig. 2012 Jun;9(2):150-3. doi: 10.4306/pi.2012.9.2.150. Epub 2012 Apr 30.
Deficits in olfactory function are common features in neurodegenerative and neuropsychiatric disorders. Olfactory processing is related to dopamine metabolism and orbitofrontal cortex functioning, both known to be involved in the neurobiology of ADHD. Some investigations suggested alterations in olfactory processing (identification and detection threshold) in patients with ADHD. Despite increasing knowledge, controversy about this topic still exists regarding children with ADHD. This study was conducted to help elucidate some of this controversy.
50 participants (8-15 years, mean=10.70±1.77) with ADHD were compared to 50 controls. The two groups were well matched for age, gender and Mean School Scores (MSS). We assessed odor identification and threshold through a smell test composed of two tests of identification and detection threshold. Odor detection threshold was assessed with the odorant phenyl ethyl alcohol solved in propylene glycol using a single staircase method. Odor identification was assessed with chemical essences of five common odorants.
The mean Sensory Identification Score for children with ADHD and the control groups were 3.76 (1.06) and 4.46 (0.76), respectively (p<0.001). The mean for Sensory Threshold Score for ADHD and control group was 6.4 (3.35) and 9.75 (2.16), respectively (p<0.001).
This study replicated altered olfactory performance in ADHD. Substantial olfactory deficits across the two domains of identification and detection threshold are observed in children with ADHD. These deficits do not seem to be a result of olfactory task difficulty and are not influenced by age, gender and MSS. Further studies are required to investigate whether olfactory function can be used as a biological marker for early diagnosis, treatment and prognosis of ADHD.
嗅觉功能障碍是神经退行性和神经精神疾病的常见特征。嗅觉处理与多巴胺代谢和眶额皮层功能有关，这两者都与 ADHD 的神经生物学有关。一些研究表明，ADHD 患者的嗅觉处理（识别和检测阈值）发生了改变。尽管知识不断增加，但关于 ADHD 儿童的这个问题仍然存在争议。进行这项研究是为了帮助阐明其中的一些争议。
将 50 名（8-15 岁，平均=10.70±1.77）ADHD 患者与 50 名对照组进行比较。两组在年龄、性别和平均学校分数（MSS）方面匹配良好。我们通过嗅觉测试来评估气味识别和阈值，该测试由两个识别和检测阈值测试组成。使用单个阶梯法评估苯乙醇的气味检测阈值，将其溶解在丙二醇中。使用五种常见气味的化学香精评估气味识别。
ADHD 儿童和对照组的平均感觉识别分数分别为 3.76（1.06）和 4.46（0.76）（p<0.001）。ADHD 和对照组的平均感觉阈值分数分别为 6.4（3.35）和 9.75（2.16）（p<0.001）。
本研究复制了 ADHD 患者嗅觉表现的改变。在 ADHD 儿童中，识别和检测阈值两个领域都存在明显的嗅觉缺陷。这些缺陷似乎不是嗅觉任务难度的结果，也不受年龄、性别和 MSS 的影响。需要进一步研究嗅觉功能是否可作为 ADHD 的早期诊断、治疗和预后的生物标志物。
