<p>Bilingualism is widespread in the world and in Russia and has been actively considered in recent years within the framework of the concept of cognitive reserve. The present article provides an overview of studies of cognitive functions in bilingual patients with neurological diseases. Cognitive disorders and dementia in bilinguals occur approximately five years later than in people who speak only one language. However, when the critical threshold of morphological changes in the brain has been overcome, dementia progresses more quickly than in monolinguals. In stroke, the incidence of aphasia in bilingual patients is no different from that in monolinguals, though recovery of speech disorders in occurs more quickly in bilinguals. The advantages of bilinguals in the cognitive domain have been shown to be related to regulatory functions – the constant need to switch from one language to another. Isolated studies have confirmed these data in patients with epilepsy. Bilingualism may be promising in the context of reducing the risk of cognitive impairment. Further research into the impact of bilingualism on cognitive status in various pathologies of the nervous system is needed.</p>