This proposed project will develop tests and methods for assessment of cognitive status in deaf older adults (aged ≥65), focusing primarily on those who use both American Sign Language (ASL) and written English to communicate. In spoken language bilinguals, sensitivity to Alzheimer’s disease (AD) is maximized when testing occurs in the dominant language, but it is not known if this applies to bilingual deaf seniors, a group that presents many challenges for assessment and diagnosis. Few tests have been developed for administration with deaf signers, and vanishingly little is known about the behavioral presentation of AD in this population. In Aim 1 we will develop tests of language proficiency, list memory, and executive function (i.e., Stroop) that can be administered in ASL or English. We will investigate which language maximizes test performance in deaf ASL-English bilinguals, information we believe is critical for avoiding a false-positive diagnosis of AD. Many seniors who were pre-lingually deaf suffered language deprivation that could alter the behavioral presentation of AD since they lacked full access to a spoken language and their use of sign language was discouraged. In Aim 2 we will test a small sample of deaf signers with probable AD to determine which language of testing maximizes differences between patients and controls (tested in Aim 1), and if deaf signers with probable AD exhibit patterns of impairment found in hearing AD (including reduced delayed recall, reduced primacy effects, increased proactive interference on list memory tests, and increased errors on Stroop tests). We will also conduct a detailed exploratory linguistic analysis of proficiency narratives, aiming to identify how AD affects production of more complex and naturalistic forms of language in deaf signers. In Aim 3 we will examine the possible effects of language deprivation and speech/sign bilingualism on cognitive reserve by recruiting 2 additional comparison groups of cognitively healthy monolingual seniors: those with normal hearing and those with late-onset aging-related deafness. Individuals who lost their hearing late-in-life have reduced exposure to linguistic interactions because of their hearing loss, and this increases their dementia risk. Comparison of these groups will provide a unique lens on the possible effects of early versus recent language deprivation on cognition. Participation of seniors with aging-related deafness will also increase the potential significance of the proposed work by providing data on written English tests which may be useful for assessment of monolingual seniors with late-life hearing loss. This project will constitute a major advancement in tests and procedures for cognitive assessment of older deaf signers, a historically disadvantaged group, will improve understanding of how diverse linguistic backgrounds may alter the behavioral presentation of AD, and will contribute to the NIA mission to “Understand health disparities...