Risk Factors for Young-Onset Dementia: A Systematic Review

Young-onset dementia (YOD), defined as dementia with onset before age 65 years, accounts for a small proportion of all dementia cases but produces substantial psychosocial, financial, and occupational burden. While autosomal dominant mutations are well-established causes of young-onset Alzheimer disease, the contribution of non-genetic factors such as vascular disease, lifestyle behaviors, metabolic conditions, and environmental exposures remains less clearly characterized. A comprehensive synthesis of both genetic and non-genetic risk factors is needed to support earlier diagnosis, preventive counseling, and targeted intervention strategies.