Hospitalization, surgery, and incident dementia

Introduction: We evaluated whether hospitalization with or without surgery increases risk for dementia or Alzheimer's disease. Methods: A clinical sample (843 clinically diagnosed dementia cases; 1686 matched nondemented individuals) was identified from Swedish Twin Registry studies. A register-based sample (4293 cases; 21,465 matched controls) was identified by linkage of Swedish Twin Registry to Swedish Patient Registry records. Apolipoprotein E (APOE) status and within-pair comparisons of dementia discordant twins indicated genetic susceptibility. Results: Nonsurgical hospitalization is associated with greater dementia risk than hospitalization with surgical intervention. In the register sample, thoracic, abdominal, and major orthopedic procedures entailed dementia risk; in the clinical sample, orthopedic alone. Within-pair analyses indicate that associations in part reflect genetic susceptibility in common to hospitalization and dementia. Potential gene-environment interactions were indicated by greater risk due to hospitalization among APOE epsilon 4 noncarriers. Discussion: We confirm hospitalization as a risk factor for dementia, with repeated hospitalizations a more important risk factor than surgery. (C) 2019 The Authors. Published by Elsevier Inc. on behalf of the Alzheimer's Association.