APOE and Alzheimer disease: APOE-ɛ4 increases pro-inflammatory cytokine production, reduces amyloid clearance and impairs blood–brain barrier integrity, all of which may amplify neural damage and Aβ accumulation related to the aetiology of MCP.58-60 Identifying biological mechanisms was beyond the scope of this study, but our findings suggest that understanding the aetiology of MCP, and how APOE-ɛ4 interacts therewith, may elucidate pathways to Alzheimer’s disease dementia.