A new study has linked loneliness with a higher risk of Alzheimer's disease and other cognitive problems.

The 2010 survey result from the American Association of Retired Persons (AARP) revealed that approximately 32 percent of adults aged between 60 and above experience loneliness. It was also disclosed that seniors with higher risk of heart disease, depression, and stroke may also develop Alzheimer's and cognitive decline.

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The study published in JAMA Psychiatry revealed that early markers of the disease were observed in brains of older adults who claimed to have been suffering from loneliness. Out of the 79 participants who were tested, 43 women and 36 men had an average age of 76 and showed normal cognitive functioning.

The possible association of amyloid protein levels in the brain with loneliness was studied. The specific protein forms plaques and serve as the disease's hallmark. The UCLA Loneliness Scale was used to measure the extent of the participants' loneliness. The tool inquires three questions including "How often do you feel left out?," "How often do you feel you lack companionship?," and "How often do you feel isolated from others?" A 4-point scale is used to answer the questions.

The researchers also conducted brain imaging to measure the levels of amyloid protein in the cortical areas of the brain.

The result showed that loneliness is 7.5 times more common among adults manifesting high levels of amyloid protein. The report also claimed that this association is greater compared to the case of participants carrying the APOEε4 gene, which increases the risk of Alzheimer's.

Dr. Nancy Donovan said "we report a novel association of loneliness and cortical amyloid burden in cognitively normal older adults and present evidence for loneliness as a neuropsychiatric symptom relevant to preclinical AD."

The researcher added that people who are socially active have lesser risk of developing the disease. Donovan stressed "people who are starting to accumulate amyloid may not be as well-functioning in terms of perceiving, understanding or responding to social stimuli or interactions," which can be an early sign of changes in cognitive or mental health.

Alzheimer's disease is considered the most common cause of dementia based on data from the U.S. National Institutes of Health.