A new US study suggests there is a strong link between loneliness and Alzheimer’s in old age.
The study is published in this month’s issue of the Archives of General Psychiatry.
Risk of developing Alzheimer’s in old age has been linked to social isolation before, but not with perceived isolation, or loneliness.
Social isolation is a measure of connectedness with one’s social environment. It can be assessed by measuring extent and quality of social contact and relationships. Loneliness on the other hand is a more subjective variable, it can only be assessed by asking people questions like how alone, empty or abandoned they feel.
Social isolation can occur without loneliness, and loneliness can occur even when one has many social contacts. Many scientists think that increasing isolation can trigger loneliness, and there is evidence to suggest that the two covary in the same direction – that is that people with the fewest social contacts feel the most lonely.
Social isolation and loneliness tend to increase with age. For example networks of family, friends and acquaintances tend to get smaller through retirement, death of family members and friends, ill health and loss of mobility.
In this longitudinal study, researchers at Rush University Medical Center in Chicago enrolled 823 senior citizens free of dementia from centres in and around the city, assessed their level of loneliness using a 5 item scale questionnaire at the start of the study and each year thereafter for 4 years. They also monitored them for signs of dementia by testing a range of cognitive functions. An assessment of of social isolation indicators was also made.
The mean loneliness score at the start of the study was 2.3 on a scale of 1 to 5.
The researchers found that loneliness was linked to lower levels of cognitive function at the start of the study, and with more rapid decline in cognitive fuction during the follow up period, but there was no significant change in loneliness overall in the group.
During the follow up period 76 of the recruits developed Alzheimer’s. The results showed that the top ten per cent most lonely people (scoring 3.2 on the loneliness scale) had 2.1 times more risk of developing Alzheimer’s compared with those in the bottom 10 per cent (scoring 1.4 on the loneliness scale). And these figures were unchanged when they controlled for isolation.
In other words the people who described themselves as most lonely were twice as likely to develop Alzheimer’s as the ones who described themselves as least lonely, regardless of how isolated they actually were.
Postmortems were carried out on the 90 people who died during the study to quantify any physical signs of Alzheimer’s in their brains. There was no link between the level of loneliness reported by the deceased and the levels of Alzheimer’s associated damage in their brains.
Dr Robert Wilson, Professor of Neuropsychology at Rush University Medical Centre and lead researcher said that the study suggests that loneliness is a real risk factor for Alzheimer’s and to understand this link we need to look outside the typical neuropathology of the disease, since there is no clear link there. He also said that this research provides good reasons to believe that loneliness is not a reaction to the disease.
Dr Wilson said that loneliness probably has a physical impact as well as an emotional impact on the old person at risk of Alzheimer’s. Perhaps loneliness affects the brain so that as people get older they are more susceptible to the age-related decline in neural pathways.
“Loneliness and Risk of Alzheimer Disease.”
Robert S. Wilson, Kristin R. Krueger, Steven E. Arnold, Julie A. Schneider, Jeremiah F. Kelly, Lisa L. Barnes, Yuxiao Tang, David A. Bennett.
Arch Gen Psychiatry. 2 February 2007;64:234-240.
Written by: Catharine Paddock
Writer: Medical News Today