Smell Identification Function in Children with Attention Deficit Hyperactivity Disorder

OBJECTIVE: 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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.

Applying a new version of the Brazilian-Portuguese UPSIT smell test in Brazil / Aplicando uma nova versão brasileira do UPSIT no Brasil

Standardized olfactory tests are now available to quantitatively assess disorders of olfaction. A Brazilian-Portuguese version of the University of Pennsylvania Smell Identification Test (UPSIT) is currently being developed specifically for the Brazilian population. The most recent Brazilian-Portuguese version of the UPSIT (UPSIT-Br2) was administered to 88 Brazilian subjects who had no history of neurological or otorhinolaryngological disease. UPSIT-Br2 scores decreased with age, were lower in men than in women, and were lower in subjects with lower income. The degree to which the poorer performance of subjects with lower socio-economic status reflects lack of familiarity with test items is not known. Although this version of the UPSIT provides a sensitive and useful test of smell function for the Brazilian population, a revision of some test items is needed to achieve comparable norms to those found using the North American UPSIT in the United States.

Testes padronizados já estão disponíveis para testagem do olfato e uma versão em Português esta sendo desenvolvida para o University of Pennsylvania Smell Identification Test (UPSIT), especificamente para a população brasileira. A versão mais recente deste teste (chamada UPSIT-Br2) foi aplicada a 88 sujeitos brasileiros que não tinham história de qualquer problema neurológico ou otorrinolaringológico. Compatível com dados prévios da literatura, a performance no UPSIT-Br2 decaiu com a idade e foi inferior no genero masculino. Os resultados foram mais baixos em participantes de menor nível sócio-econômico e a relação deste achado com a falta de familiaridade para com os itens do teste não é conhecida. Apesar desta versão do UPSIT poder ser útil para o teste da função olfativa da população brasileira, a revisão de alguns itens se faz necessária para alcançar valores comparáveis aos dados normativos norte-americanos.