The mismatch negativity as an index of cognitive impairment in adults with Down syndrome

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Abstract Background People with Down syndrome (DS) have a high risk of developing Alzheimer’s disease (AD; Zis and Strydom 2018). The mismatch negativity (MMN) is an event‐related potential that can be used to index cognitive decline (Näätänen et al., 2011). Given its relative independence from attentional processes (Naatanen and Näätänen 1992), the MMN may be particularly useful when studying populations with intellectual disability, who may find sustained attention tasks challenging. We therefore investigated the MMN in people with DS and its association with cognitive abilities. Methods MMN responses to a passive auditory oddball task were recorded from 27 adults with DS (aged 18 to 59) without any hearing impairments. Associations between MMN and age, as well as memory, language, IQ, and attention scores were examined. Results The MMN was present only in young adults up to the age of 40 and the latency was prolonged. Attenuation of MMN amplitude was associated with poorer memory scores. Finally, longer MMN latencies were associated with increased inter‐individual performance variability and worse performance on memory, verbal, and general IQ tasks. Conclusion Overall, our results indicate that MMN amplitude may be associated with AD‐related memory loss, while increased MMN latency seems to reflect verbal abilities in people with DS. Furthermore, the association between MMN latency and inter‐individual performance variability may suggest the presence of AD‐driven white matter degenerations affecting the brian’s frontal lobe. Therefore, the MMN may represent a valuable tool for studying cognitive abilities and AD pathology in DS. References : Naatanen R, Näätänen R. 1992. Attention and brain function. Psychology Press. Näätänen R, Kujala T, Kreegipuu K, Carlson S, Escera C, Baldeweg T, Ponton C. 2011. The mismatch negativity: an index of cognitive decline in neuropsychiatric and neurological diseases and in ageing. Brain 134(12):3435‐3453. Zis P, Strydom A. 2018. Clinical aspects and biomarkers of Alzheimer’s disease in Down syndrome. Free Radical Biology and Medicine 114:3‐9.

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