Loneliness may help set the stage for Alzheimer's disease. But if this
is the case, it does not seem to do so by increasing the number of plaques and
tangles in the brain.
A classic Southern novel, The Heart Is a Lonely Hunter, by Carson
McCullers, focuses on the theme of loneliness in people's lives and how it can
drive them not just to despair, but to suicide.
But loneliness may have another pernicious effect as well—Alzheimer's
disease. Chicago researchers have found that it doubles people's chance of
developing the illness.
Robert Wilson, Ph.D., a professor of neuropsychology at Rush University
Medical Center in Chicago, led the study team, whose results appeared in the
February Archives of General Psychiatry.
The study involved more than 800 older people without dementia whom they
recruited from senior-citizen facilities in and around Chicago. Wilson and his
coworkers assessed these individuals for perceived loneliness at the start of
the study and then annually for four years.
“I experience a general sense of emptiness,” “I miss
having people around,” “I often feel abandoned,” and“
I miss having a really good friend” were some of the statements
that subjects expressed when they were experiencing loneliness.
The brains of subjects who died during this four-year period were examined
for Alzheimer's; 76 were found to have had it.
Wilson and his team then looked to see whether loneliness could be linked
to acquiring Alzheimer's and found that it could. The risk of Alzheimer's was
more than doubled in lonely persons.
Moreover, the investigators had evaluated the subjects for depression, both
at the start of the study and annually during the four-year follow-up. They
also found a link between depression and the risk of Alzheimer's. But when
they scrutinized the relative contributions of loneliness and depression to
Alzheimer's risk, the contribution of the former was stronger. In fact, they
found that a question on the depression questionnaire that pertained more to
loneliness than to depression predicted the occurrence of Alzheimer's more
reliably than did the remaining questions that more directly focused on
depression per se.
“These data,” Wilson and his group wrote, “suggest that
the association of loneliness with dementia is at least partly independent of
depressive symptoms... [and that] loneliness may be an important component of
the association of depressive symptoms with Alzheimer's.”
And even when some other possibly confounding factors besides depression
were taken into consideration, the link between loneliness and Alzheimer's
remained potent. (These factors, along with loneliness and depression, were
measured in subjects at the start of the study and annually during the
For example, lack of physical and mental activity are known Alzheimer's
risk factors. When the former was taken into consideration, the link between
loneliness and Alzheimer's remained just as strong as before, and when the
latter was taken into account, the link between loneliness and Alzheimer's was
weakened, but only a little (about 15 percent).
“The most interesting part of the results to me,” Wilson told
Psychiatric News, “was that the subjective feeling of
loneliness predicted development of Alzheimer's disease even after we
controlled for objective indices of social engagement such as the size of
one's social network or frequency of socially interactive
That loneliness predicts the development of Alzheimer's, of course, does
not prove that loneliness is a cause of it, Wilson and his group said in their
study report. It could also be that loneliness is a consequence of dementia,
perhaps as a behavioral reaction to diminished cognition or as a direct result
of the pathology contributing to dementia. However, they do not believe that
that is the case for various reasons. For example, although loneliness
predicted a decline in cognition, a decline in cognition did not predict an
increase in loneliness.
Yet, presuming that loneliness does contribute to Alzheimer's in some
manner, how might it do so? Wilson and his colleagues suspect that loneliness
might somehow compromise neurons underlying thinking and memory, and if that
is the case, then these neurons might be less capable of “pinch
hitting” for neurons afflicted with the Alzheimer's disease process.
Indeed, in some preclinical studies, animals subjected to social isolation
showed fewer neuronal connections in the prefrontal cortex and hippocampus
than did animals that were not isolated.
In any event, “all participants in this study, which is ongoing, have
agreed to brain autopsy at death,” said Wilson. He then hopes to use the
harvested brain material to hunt for changes that loneliness
inflicts—changes that might prep the brain for the Alzheimer's disease
The investigation was funded by the National Institute on Aging and the
Illinois Department of Public Health.
An abstract of “Loneliness and Risk of Alzheimer
Disease” is posted at<http://archpsyc.ama-assn.org/cgi/content/abstract/64/2/234>.▪