The authors noted that whilst social isolation in old age had been associated with the risk of developing dementia, the risk associated with loneliness was not well understood. They hypothesised that loneliness is associated with increased risk of Alzheimer’s disease. A total of 823 older persons were recruited from senior citizen facilities in and around Chicago. At death, a uniform post-mortem examination of the brain was conducted to quantify Alzheimer’s disease pathology within the brain. During follow-up, 76 subjects developed clinical Alzheimer’s disease with the risk of developing Alzheimer’s disease more than doubling in those who were lonely.
Wilson RS, Krueger KR, Arnold SE, Schneider JA, Kelly JF, Barnes LL, Tang Y, Bennett DA. Loneliness and risk of Alzheimer disease. Arch Gen Psychiatry. 2007;64(2):234–40.