Midlife Atherosclerosis and Development of Alzheimer or Vascular Dementia

OBJECTIVE: To investigate whether midlife atherosclerosis is associated with different dementia subtypes and related underlying pathologies. METHODS: Participants comprised the cardiovascular cohort of the Swedish prospective population‐based Malmö Diet and Cancer Study (N = 6,103). Carotid plaques and intima media thickness (IMT) were measured at baseline (1991–1994). Dementia incidence until 2014 was obtained from national registers. Diagnoses were reviewed and validated in medical records. In a cognitively unimpaired subcohort (n = 330), β‐amyloid(42) and tau were quantified in cerebrospinal fluid (CSF), and white matter hyperintensity volume, lacunar infarcts, and cerebral microbleeds were estimated on magnetic resonance imaging (2009–2015). RESULTS: During 20 years of follow‐up, 462 individuals developed dementia (mean age at baseline = 57.5 ± 5.9 years, 58% women). Higher IMT in midlife was associated with an increased hazard ratio (HR) of all‐cause dementia (adjusted HR = 1.14 [95% confidence interval (CI) = 1.03–1.26]) and vascular dementia (adjusted HR = 1.32 [95% CI = 1.10–1.57]) but not Alzheimer disease (AD) dementia (adjusted HR = 0.95 [95% CI = 0.77–1.17]). Carotid plaques were associated with vascular dementia when assessed as a 3‐graded score (adjusted HR = 1.90 [95% CI = 1.07–3.38]). In the cognitively unimpaired subcohort (53.8 ± 4.6 years at baseline, 60% women), higher IMT in midlife was associated with development of small vessel disease (adjusted odds ratio [OR] = 1.47 [95% CI = 1.05–2.06]) but not significantly with abnormal CSF AD biomarkers (adjusted OR = 1.28 [95% CI = 0.87–1.90] for Aβ(42) and 1.35 [95% CI = 0.86–2.13] for Aβ(42)/p‐tau). Carotid plaques revealed no significant association with any of the underlying brain pathologies. INTERPRETATION: Our findings support an association between midlife atherosclerosis and development of vascular dementia and cerebral small vessel disease but not between atherosclerosis and subsequent AD dementia or AD pathology. ANN NEUROL 2020;87:52–62