Loneliness sparks risk of Alzheimer's disease

A new US study found that lonely individuals are twice as likely to develop the type of dementia linked to Alzheimer's disease, progressive brain disorder in late life.

Researchers from the Rush University Medical Center in Chicago found that loneliness was associated with an increased risk of late-life dementia but was not its leading cause.

Alzheimer's disease, the most common type of dementia, is a neurodegenerative disease characterized by progressive cognitive deterioration together with declining activities of daily living and neuropsychiatric symptoms or behavioral changes.

Its most striking early symptom is loss of short term memory that usually becomes more pronounced as the illness progresses.

The study recruited 823 elderly patients averaging 80.7 years, free of dementia at enrollment. They were followed over a four-year period.

The participants were assessed and ranked for their loneliness on a five-point scale at baseline and annually thereafter. They received annual mental check-ups.

During the course of study 76 participants showed signs of clinical Alzheimer's disease.

Risk of developing the disease doubled as the scores of loneliness increased. Those with the highest loneliness score of 3.2 had about 2.1 times the risk of developing Alzheimer's disease compared to those with a low score of 1.4, researchers found.

Moreover, controlling for indicators of social isolation did not affect the finding.

For 90 participants who died during the study, a uniform postmortem examination of the brain was conducted to quantify Alzheimer's disease pathology in multiple brain regions and the presence of cerebral infarctions.

Results for autopsy of the brain in dead was not related to any of the hallmark brain changes associated with Alzheimer's disease.

"The results suggest that loneliness may contribute to risk of an Alzheimer's disease–like dementia in late life and does so through some mechanism other than Alzheimer's disease pathology and cerebral infarction," researchers marked.

"More research is needed to understand the exact link between loneliness and dementia symptoms. Leisure activities may help the brain keep a 'reserve' capacity capable of delaying the onset of the clinical symptoms of dementia,” Dr Susanne Sorensen, Head of Research at the Alzheimer's Society stated.

Dementia and social isolation has already been shown to be linked, but this is the first time researchers have looked at how alone people actually felt.

The study features in the February issue of Archives of General Psychiatry.