Association of Covert Cerebrovascular Disease Identified Using Natural Language Processing and Future Dementia

ABSTRACT Objective To estimate the risk of dementia associated with incidentally-discovered covert cerebrovascular disease (CCD), including both covert brain infarction (CBI) and white matter disease (WMD). Patients and Methods We included individuals aged ≥ 50 years enrolled in the Kaiser Permanente Southern California health system receiving a head CT or MRI for a non-stroke indication from January 1, 2009 and December 31, 2019, without prior ischemic stroke, transient ischemic attack, hemipelegia, hemiparesis, dementia/Alzheimer’s disease or a visit reason / scan indication suggestive of cognitive decline. Using natural language processing (NLP), we identified the presence of CBI and WMD on the neuroimage report; WMD was characterized as mild, moderate, severe, or undetermined. Results Among 241,050 qualified individuals, NLP identified 69,931 (29.0%) with WMD and 11,328 (4.7%) with CBI. The dementia incidence rates (per 1,000 person-years) were 23.5 (95% CI 22.90 to 24.0) for patients with WMD; 29.4 (95% CI 27.9 to 31.0) with CBI and 6.0 (5.8 to 6.2) without CCD. The effect of WMD on dementia risk was stronger in younger versus older patients and for CT-versus MRI-discovered lesions. For patients with versus without WMD on CT scan, the adjusted HR (aHR) was 2.87 (2.58 to 3.19) for those < age 70 and 1.87 (1.79 to 1.95) for those ≥ age 70. For patients with versus without WMD on MRI, the aHR for dementia risk was 2.28 (1.99 to 2.62) for patients < age 70 and 1.48 (1.32 to 1.66) for those ≥ age 70. The aHR associated with CBI was 2.02 (1.70 to 2.41) for patients age <70 and 1.22 (1.15 to 1.30) for patients age ≥70 for either modality. Dementia risk with WMD was strongly correlated with WMD severity. Conclusion Incidentally-discovered CCD is common and identifies patients at high risk of dementia, representing an opportunity for prevention.