People who experienced high anxiety any time in their lives had a 48 percent higher risk of developing dementia compared to those who had not, according to a new. The findings were based on an examination of 28 years of data from the Swedish Adoption Twin Study of Aging, overseen by the Karolinska Institutet of Sweden.
The study sample involved 1,082 participants, twins, fraternal and identical, who completed in-person tests every three years, answered several questionnaires and were screened for dementia throughout the study. Many other studies have explored the link between dementia and psychological variables such as depression and neuroticism. However, this study established that the anxiety-dementia link was independent of the role of depression as a risk factor.
“Anxiety, especially in older adults, has been relatively understudied compared to depression,” said Andrew Petkus, the study’s lead author and postdoctoral research associate of psychology at the USC Dornsife College of Letters, Arts and Sciences. “Depression seems more evident in adulthood, but it’s usually episodic. Anxiety, though, tends to be a chronic lifelong problem, and that’s why people tend to write off anxiety as part of someone’s personality.”
The researchers noted that the subjects had self-reported various levels of anxiety, which may or may not meet the clinical diagnostic threshold of a psychiatric anxiety disorder. Even so, the twin who developed dementia had a history of higher levels of anxiety compared to the twin who did not develop dementia.
People who have high levels of anxiety tend to have higher levels of stress hormones, including cortisol. Evidence shows that chronically high levels of cortisol damage parts of the brain such as the hippocampus, which stores memory, and the frontal cortex, which is responsible for high-level thinking.
The researchers also found that the anxiety-dementia relationship was stronger among fraternal twins, who had only one develop dementia, than among identical twins. The researchers said this finding indicates that there may be genetic factors shared by anxiety and dementia that account for the anxiety-dementia risk.
The USC team also hopes to determine whether individuals who have been treated for anxiety earlier in their lives show lower risk of dementia compared with those whose anxiety was not treated.