Abstract / Summary
Background/Objectives: Pain is a common and disabling non-motor manifestation of neurodegenerative disorders, but the contribution of glial cells to nociceptive processing remains incompletely understood. This systematic review evaluated evidence from preclinical models of neurodegenerative diseases linking microglial and astrocytic activity to pain. Methods: The protocol was prospectively registered in PROSPERO (CRD420251084310), and reporting followed PRISMA 2020. We conducted the original electronic search in PubMed/MEDLINE; during major revision, we conducted supplementary searches in Scopus and Web of Science Core Collection. Across the three sources, we identified 2248 records. After hierarchical deduplication by DOI, PMID, and normalized title, 1567 unique records were screened. Eligible in vivo studies assessed microglial and/or astrocytic alterations together with pain- or nociception-related outcomes. Risk of bias was independently evaluated by two investigators using the SYRCLE tool, and findings were synthesized qualitatively. Results: Twenty-six studies met the eligibility criteria: sixteen examined multiple sclerosis/experimental autoimmune encephalomyelitis (61.5%), seven Parkinson’s disease (26.9%), two Alzheimer’s disease-related models (7.7%), and one Huntington’s disease model (3.8%); no eligible amyotrophic lateral sclerosis study was identified. Pain-related alterations involved inflammatory, neuroimmune, synaptic, and astrocyte-associated pathways, but the evidence was strongly model-dependent. Findings based on individual studies, including early astrocytic contributions in experimental autoimmune encephalomyelitis and altered inflammatory allodynia in an Alzheimer’s disease model, are interpreted as study-specific observations requiring replication. Conclusions: The available evidence supports context-dependent associations between glial responses and nociceptive processing; however, marker specificity, EAE predominance, sex and age imbalance, and incomplete reporting of bias control procedures limit causal and cross-disease generalization.