This article examines the relationship between cognitive impairment and neurodegeneration in patients with Alzheimer’s disease, with particular attention to the presence or absence of bilingualism. The concepts of cognitive and cerebral reserve are explored, along with findings from studies evaluating the effects of bilingualism on cognitive reserve and on the preservation of brain function during neurodegeneration. Bilingualism is identified as a multifaceted phenomenon encompassing various components of language experience, such as proficiency level, functional language use, language of education, age of second-language acquisition, societal status of languages, and language switching. These factors complicate research on how bilingualism influences the progression of cognitive impairment in neurodegenerative settings. The article discusses the methodological challenges inherent in bilingualism research and considers the potential influence of learning additional languages on the development of cerebral structures and neuronal connections, as shaped by language experience. The review details findings from studies investigating the impact of bilingualism on the onset and progression of Alzheimer’s disease. Overall, the evidence suggests that the relationship between bilingualism and Alzheimer’s disease is complex and multifactorial. Current data indicate that bilingualism is likely a significant contributor to cognitive reserve, although interpretation of research findings is frequently complicated by methodological limitations.