EMBARGOED FOR RELEASE UNTIL 4 PM ET, July 12, 2023
Social Isolation Linked to Lower Brain Volume
MINNEAPOLIS 鈥 Older people who have little social contact with others may be more likely to have loss of overall brain volume, and in areas of the brain affected by dementia, than people with more frequent social contact, according to a study published in the July 12, 2023, online issue of , the medical journal of the 好色先生. The study does not prove that social isolation causes brain shrinkage; it only shows an association. 鈥淪ocial isolation is a growing problem for older adults,鈥 said study author Toshiharu Ninomiya, MD, PhD, of Kyushu University in Fukuoka, Japan. 鈥淭hese results suggest that providing support for people to help them start and maintain their connections to others may be beneficial for preventing brain atrophy and the development of dementia.鈥 The study involved 8,896 people with an average age of 73 who did not have dementia. They had MRI brain scans and health exams. To determine social contact, people were asked one question: How often are you in contact with relatives or friends who do not live with you (e.g., meeting or talking on the phone)? The choices for answering were every day, several times a week, several times a month and seldom. The people with the lowest amount of social contact had overall brain volume that was significantly lower than those with the most social contact. The total brain volume, or the sum of white and grey matter, as a percentage of the total intracranial volume, or the volume within the cranium, including the brain, meninges, and cerebrospinal fluid, was 67.3% in the lowest contact group compared to 67.8% in the highest contact group. They also had lower volumes in areas of the brain such as the hippocampus and amygdala that play a role in memory and are affected by dementia. The researchers took into account other factors that could affect brain volume, such as age, diabetes, smoking and exercise. The socially isolated people also had more small areas of damage in the brain, called white matter lesions, than the people with frequent social contact. The percentage of intracranial volume made up of white matter lesions was 0.30 for the socially isolated group, compared to 0.26 for the most socially connected group. The researchers found that symptoms of depression partly explained the relationship between social isolation and brain volumes. However, symptoms of depression accounted for only 15% to 29% of the association. 鈥淲hile this study is a snapshot in time and does not determine that social isolation causes brain atrophy, some studies have shown that exposing older people to socially stimulating groups stopped or even reversed declines in brain volume and improved thinking and memory skills, so it鈥檚 possible that interventions to improve people鈥檚 social isolation could prevent brain volume loss and the dementia that often follows,鈥 Ninomiya said. Since the study involved only older Japanese people, a limitation is that the findings may not be generalizable to people of other ethnicities and younger people. The study was supported by the Japan Agency for Medical Research and Development and Suntory Holdings Limited. Learn more about brain health at , home of the 好色先生鈥檚 free patient and caregiver magazine focused on the intersection of neurologic disease and brain health. Follow Brain & Life庐 on , and . When posting to social media channels about this research, we encourage you to use the hashtags #Neurology and #AANscience.