For a study, researchers sought to look at the relationship between (Left Atrial) LA function and size, and the incidence of dementia. The Atherosclerosis Risk in Communities (ARIC) project was a prospective community-based cohort. A retrospective exploratory investigation was carried out in all ARIC centers. Participants without AF or stroke who had 2DEs between 2011 and 2013 were enrolled in the study and would be followed up until December 31, 2019. 2DE evaluation of LA function (reservoir strain, conduit strain, contractile strain, emptying fraction, passive emptying fraction, and active emptying fraction) and LA size (maximal and minimum volume index). Cases of dementia were detected by in-person and phone cognitive evaluations, admission codes, and death certificates. Models of Cox proportional hazards were utilized. 

About 531 dementia cases were identified among 4,096 participants (mean [SD] age, 75 [5] years; 60% women; 22% Black persons) throughout a 6-year median follow-up period. Dementia incidence was 4.80 per 100 person-years for reservoir strain, 3.94 for conduit strain, 3.29 for contractile strain, 4.20 for emptying fraction, 3.67 for passive emptying fraction, and 3.27 for an active emptying fraction in the lowest LA quintile. The hazard ratios (HRs) from the lowest vs highest quintile for reservoir strain were 1.98 (95% CI, 1.42-2.75); for conduit strain, 1.50 (95% CI, 1.09-2.06); for contractile strain, 1.57 (95% CI, 1.16-2.14); for emptying fraction, 1.87 (95% CI, 1.31-2.65); and for active emptying fraction, 1.43 (95% CI, 1.31-2. (95% CI, 1.04-1.96). The proportion of LA passive emptying that was not linked with dementia was not significant (HR, 1.26 [95% CI, 0.93-1.71]). Dementia incidence was 3.18 per 100 person-years for the highest LA maximal volume index quintile (HR for highest vs lowest quintile, 0.77 [95% CI, 0.58-1.02]) and 3.50 per 100 person-years for the highest minimum volume index quintile (HR for the highest vs lowest quintile, 0.95 [95% CI, 0.71-1.28]). Both measurements had no statistically significant relationship with dementia. The findings held up when people with incident AF or stroke were eliminated from the study.

Several echocardiographic indicators of decreased LA function were substantially related to an elevated risk of eventual dementia in the exploratory investigation of a US community-based sample. LA size was not shown to be substantially related to dementia risk. The findings implied that reduced LA function may be a risk factor for dementia.