Multiple linear regression analysis was performed for loneliness, measured by the 3-item UCLA-3 Loneliness Scale (higher score indicates greater loneliness), as the dependent variable. Evaluated associations included amyloid burden (a continuous aggregate measure of cortical amyloid by Pittsburgh Compound B–positron emission tomography [PiB-PET] distribution volume ratio [DVR]), age, sex, apolipoprotein E ε4 (APOEε4) carrier status, Hollingshead score, depression, anxiety, and social network score.