Background Neurodegenerative diseases (NDs), such as Alzheimer’s disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS), significantly affect the daily lives of patients. Shared risk factors for this group of diseases include age, genetic background, socioeconomic status, metabolic conditions, and environmental toxin exposure. Veterans are particularly vulnerable to these conditions due to their unique military experiences and exposures. This study aims to identify distinct risk factors for NDs in the veteran population, providing insights for tailoring clinical interventions to this unique patient population.

Methods This systematic review was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. In June 2024, a comprehensive search was conducted using the following electronic databases: PubMed, MEDLINE, EMBASE, Cochrane Database, and Scopus, focusing on studies published between 2000 and 2024. Search terms included combinations of MeSH terms and keywords such as “neurodegenerative diseases,” “veterans,” “military,” “risk factors,” “Alzheimer’s disease,” “Parkinson’s disease,” “ALS,” and “MS.” Inclusion criteria focused on peer-reviewed articles, cohort studies, case-control studies, and case series investigating ND risk factors in veterans. Publications not in English, opinion pieces, and non-human studies were excluded.

Results Unique risk factors for NDs in veterans include environmental toxin exposure, combat-related physical injuries, and psychological impact of military service. Environmental agents, like Agent Orange, herbicides, neurotoxins, chlorinated solvents, and other chemical warfare agents were significant factors. Physical military injuries, such as traumatic brain injuries (TBI), hearing loss, and visual impairments, have been linked to a higher incidence in NDs and neurotrauma. Veterans have long been known to be affected by the psychiatric effects of military experiences, specifically post-traumatic stress disorder (PTSD). Recent research has suggested a connection between the PTSD and eventual cognitive decline associated with NDs.

Conclusion Identifying the military-related risk factors in developing NDs underscores the multifactorial nature of NDs while highlighting the unique life experiences of veterans that contribute to their neurological decline. This study emphasizes the importance of understanding patient backgrounds to devise effective preventive measures and therapeutic approaches. Future research should prioritize longitudinal studies to further elucidate these associations and enhance intervention strategies.