Recently, more attention is being given to identifying aging-related and dementia-related pathological changes in performance and cognition among persons with intellectual disabilities (ID). This literature review examines age-related differences in specific aspects of cognitive functioning and cognitive performance of people with ID and Alzheimer's disease (AD), as well as what maybe be protective and risk factors. Training interventions designed to enhance cognitive performance are also reviewed. The authors note that greater efforts are urgently needed with respect to delineating the function and deficits in cognitive domains within aging adults. Methodological issues that merit further attention includes utilizing appropriate age ranges and assessment of intra-individual variability in statistical analysis of cognitive performance. While, consideration should be given to the continued development of specific cognitive tasks and tests that have been developed, validated, and normed for this population, there is still a critical need for more longitudinal data with multiple time points, to assess and track trajectories of change over time, especially as cohort effects of residential living, and educational and vocational opportunities have varied so widely over the last 30 years, and are likely to be a substantial confounding factor. Furthermore, efforts need to ensure that instruments continue to be developed with specificity and sensitivity to detect pathological deficits in AD-related performance. Lastly, greater research attention is warranted to describe and meet the needs of the burgeoning aging population of people with ID. This will ultimately guide policy makers to develop better practice protocols to maximize cognitive function in normative and pathological aging.