The association of seizure control with neuropathology in dementia.

Seizures in people with dementia (PWD) are associated with faster cognitive decline and worse clinical outcomes. However, the relationship between ongoing seizure activity and postmortem neuropathology in PWD remains unexplored. We compared post-mortem findings in PWD with active, remote, and no seizures using multicentre data from 39 Alzheimer's Disease Centres from 2005 to 2021. PWD were grouped by seizure status into active (seizures over the preceding one year), remote (prior seizures but none in the preceding year), and no seizures (controls). Baseline demographics, cognition, mortality, and postmortem findings of primary and contributing(co-pathologies) Alzheimer's Disease(AD), Frontotemporal lobar degeneration(FTD), Lewy body, vascular pathologies and neurodegeneration were compared among the groups using Pearson's Chi-squared test, fisher's exact test, t-test, and ANOVA tests. Of 10,474 deceased PWD, active seizure participants suffered the highest mortality among the groups(proportion deceased among the groups: active=56%remote=35%, controls=34%, p<0.001). Among 6085 (58.1% of deceased) who underwent autopsy, 294 had active, 151 had remote, and 5640 had no seizures. PWD and active seizures died at a younger age (Active=75.8, remote=77.9, controls: 80.8 years, p <0.001) and had more severe dementia (CDR-Global: active=2.36, remote=1.90, controls=1.69, p<0.001). In post hoc analyses, those with primary postmortem diagnosis of AD with active seizures had more severe and later stages of AD pathology and ATN (amyloid, tau, and neurodegeneration) as evidenced by Braak stage for neurofibrillary(tau) degeneration and CERAD score density of neuritic(amyloid) plaques than remote seizure participants and controls. Active seizure participants had more neurodegeneration, evidenced by cerebral atrophy, hippocampal atrophy, and locus coeruleus hypopigmentation than controls. Among participants with primary postmortem diagnosis of non-AD, in posthoc analyses, active seizure participants had worse AD co-pathology evidenced by higher Braak stages than remote seizures and controls and a higher thal phase of beta-amyloid plaques than controls. Neurodegeneration (cerebral/hippocampal atrophy) and LC hypopigmentation were comparable among the groups. In both primary postmortem AD and non-AD diagnoses, FTD (co)pathology was less prevalent among active seizure participants than controls, while vascular pathology, Circle of Willis atherosclerosis, Lewy body pathology, lobar atrophy, and substantia nigra hypopigmentation were comparable among the three groups. This study shows that active, compared to remote seizures, are associated with earlier death and postmortem evidence of more severe ATN pathology. Active seizures are associated with more advanced AD pathology in AD and worse AD co-pathology in non-AD dementias. Therefore, clinicians should be vigilant in detecting ongoing seizures as this could reflect a worse prognosis in PWD.