Anxiety 'increases risk' of developing dementia

People who experience high anxiety are one and a half times more likely to develop dementia, according to a new study led by University Southern Californian (USC) researchers.

Although previous research has linked dementia with psychological problems such as depression and neuroticism, this is the first to establish an anxiety-dementia link.

Andrew Petkus, the study’s lead author, said: “Anxiety, especially in older adults, has been relatively understudied compared to depression.

“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 findings were based on an examination of 28 years of data from the Swedish Adoption Twin Study of Ageing. The study sample involved 1,082 participants — twins, fraternal and identical — who completed tests every three years, answered several questionnaires and were screened for dementia throughout the study.

To determine whether anxiety levels correlated to dementia risk, researchers compared those who reported high anxiety with those who reported lower anxiety levels.

Mr Petkus explained that those who had high levels of anxiety had higher levels of stress hormones, including cortisol. Evidence shows that high levels of cortisol damages parts of the brain such as the hippocampus and the frontal cortex, which are responsible for high-level thinking.

Researchers also found that the anxiety-dementia relationship was stronger among fraternal twins than identical twins. This finding could indicate that there may be genetic factors shared by anxiety and dementia that account for the anxiety-dementia risk.

Margaret Gatz, co-author of the study, has suggested that participants with anxiety who later developed dementia “are people that experience more than usual symptoms of anxiety."

"They are people who you would say operate at a ‘high level of anxiety. They are frantic, frazzled people,”she said.

Previous 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.

The USC researchers also hope 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.

The Swedish Adoption Twin Study of Ageing is funded by grants by the MacArthur Foundation Research Network on Successful Ageing, the Swedish Council for Working Life and Social Research and the Swedish Research Council.

A final draft of the study has been published online in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.