Bilingualism has been associated with a successful cognitive aging. Thus, research has shown how bilingualism provides cognitive advantages. Among these cognitive advantages, we can find an improvement in the control of interference (aspect related to a better selective attention) and a delay in the appearance of signs of dementia. However, there is no firm confirmation or unanimity in considering this cognitive advantage in bilinguals as a certainty without questions. In addition, research in this field and on the neuronal bases that support this cognitive advantage in bilingual elderly populations, compared to monolingual, is very poor and insufficient.
In this study, after the administration of several tests, among them the Simon task, it was possible to see how the behavioral performance was equivalent in the two samples of participants. However, the used underlying neural substrates and brain activation maps were different between monolingual and bilingual participants, because monolinguals activated right frontal regions, while bilinguals activated the left lower parietal lobe. For this reason, the results show that both the bilingual and monolingual elderly population have equivalent interference control abilities, although the neural substrates are different. In this way, it has been possible to show how monolinguals base their control on frontal areas and use a different circuit from that of bilinguals, since the bilingual population activates regions involved in visual space processing. Thus, this fact indicates that bilingual elderly people, to carry out tasks that require a high petition of mental resources, use a circuit that is not especially vulnerable to aging or dementia.
Therefore, it was concluded that bilingualism has some benefits in the functioning of the brain ant in the processing of cognitive control. Based on this evidence, it is suggested that the bilingual advantage exists, although the behavioral performance has been equivalent in the two populations and they have not shown a behavioral advantage.
Reference: Ansaldo AI, Ghazi Saidi L, Adrover-Roig D. (2015). Interference control in elderly bilinguals: appearances can be misleading. Journal of Clinical and Experimental Neuropsychology;37(5):455-70.