A new study found anxiety was linked to a 48 percent increase in the chance of dementia.
Researchers at the University of Southern California have found that people who experienced high levels of anxiety any time in their lives have a 48 percent higher chance of developing dementia compared to anxiety-free folks.
The study looked at 1,082 people — twins, both fraternal and identical — and examined 28 years of data from the Swedish Adoption Twin Study of Aging. The study participants answered several questionnaires, completed in-person tests every three years, and were also screened for dementia throughout the study.
Compared to depression, anxiety hasn’t been as widely studied when looking for links to brain-degenerative diseases later in life. Previous research has explored the link between dementia and other psychological conditions like depression and neuroticism. But now, the USC researchers have shown that the anxiety-dementia link is independent of depression as a risk factor.
"Anxiety, especially in older adults, has been relatively understudied compared to depression," Andrew Petkus, the study's lead author and postdoctoral research associate of psychology in the USC Dornsife College of Letters, Arts and Sciences, said in a press release. "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."
It’s important to note that the subjects self-reported their various levels of anxiety, so different thresholds for anxious feelings could have skewed the accuracy of the findings a bit. However, the researchers found that in pairs of twins in which one twin would go on to develop dementia, the twin who developed the illness had a history of higher levels of anxiety compared to the twin who stayed clear of dementia.
"They are people who you would say operate at a 'high level of anxiety,'" study co-author Margaret Gatz, a professor of psychology in the USC Dornsife College of Letters, Arts and Sciences, and a foreign adjunct professor for the Karolinska Insitutet, said in the press release. "They are frantic, frazzled people.”
The researchers also compared the study participants with low-levels of anxiety to those with high-levels. "Those in the high anxiety group were about 1.5 times more likely to develop dementia," Petkus said.
The link between anxiety and dementia could potentially be explained by cortisol, a stress hormone. Those with higher levels of anxiety tend to have higher levels of stress hormones, and previous research has shown that high levels of cortisol can damage parts of the brain, including the hippocampus, which stores memory, and the frontal cortex, which is responsible for high-level thinking.
Next up, the USC team wants to determine whether individuals who have been treated for anxiety earlier in life show a lower risk of dementia compared to those who didn’t get treatment for their anxiety.
The study is published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.