Common mental disorder identified as tripling risk of dementia

Much depends on the time of experiencing this condition

Anxiety is, to put it mildly, an unpleasant mental disorder that can occur even in quite stable people. This condition can appear due to many factors, including prolonged exposure to stress. Anxiety can affect the normal functioning of various body systems. Now scientists are proving that this mental disorder can almost triple the risk of developing dementia in the future.

Photo: freepik.com

The study, published Wednesday in the Journal of the American Geriatrics Society, is the first to examine the association between varying levels of anxiety and dementia risk over time, as well as how the timing of anxiety affects that risk.

«Anxiety can now be considered a non-traditional risk factor for dementia,» said lead study author and geriatrician at Hunter New England Health in Newcastle, Australia, Dr Kay Khine.

More than 55 million people worldwide suffer from dementia, and that number is expected to rise to 139 million by 2050, according to CNN. Because the disease is also a leading cause of death, researchers and health professionals have focused on prevention, particularly by addressing risk factors such as anxiety or lifestyle habits.

Previous studies examining the link between anxiety and dementia have mostly measured participants' anxiety at a single point in time, yielding mixed findings. However, the authors argue that the duration of a person's anxiety is an important aspect worth considering.

The team studied 2,132 participants recruited from the Hunter Community Study in Newcastle between December 2004 and December 2007. Participants were aged between 60 and 81 years and over, and provided health information such as tobacco or alcohol use and whether they had medical conditions such as hypertension or diabetes at the start of the study.

Three assessments, also called waves, were conducted, each five years apart. The researchers measured participants' anxiety during the first and second assessments. Chronic anxiety was defined as the presence of anxiety during the first and second waves. A person's anxiety was considered resolved if they experienced anxiety only during the first wave. New-onset anxiety refers to anxiety identified only during the second wave.

Dementia was identified using International Statistical Classification of Diseases codes or pharmaceutical benefits data reflecting the purchase of dementia medications provided by the Australian Department of Health and Aged Care.

Eventually, 64 participants developed dementia. Chronic and new-onset anxiety were associated with an almost threefold higher risk of dementia from any cause — with a median time to diagnosis of 10 years, the authors found.

Anxiety that resolved within the first five years was so unrelated to a greater risk of developing dementia that the odds were similar to those of those who had no anxiety at all — a finding that Dr. Glen R. Finney, a fellow of the American Academy of Neurology, called «a welcome addition to our knowledge of anxiety and dementia.»

“We've known for a long time that stress increases the risk of Alzheimer's disease. This study is consistent with earlier research that shows that therapy aimed at relieving anxiety can help reduce the risk of Alzheimer's disease. But it's the size of this study that's particularly compelling,” said Dr. Rudolph Tanzi, director of the McCance Center for Brain Health at Massachusetts General Hospital in Boston, who was not involved in the study.

The latest study’s authors didn’t have information on what specifically helped some participants overcome their anxiety. But the results clearly highlight “the importance of addressing anxiety early and consistently,” says neurologist Joel Salinas, founder and chief medical officer of Isaac Health, a virtual and in-home clinical service for people with dementia and other brain diseases.

The study has several limitations, including that participants’ anxiety measures were based on four weeks before the assessment, the authors say. The team also lost 33% of participants who had higher levels of anxiety at the start of the study. Not knowing what ultimately happened to these people may have led to an underestimation of the impact of anxiety on dementia.

The link between anxiety and dementia may be partly explained by the former's association with vascular disease and its harmful effects on cells, experts say.

Stress increases cortisol levels in the brain and increases inflammation, both of which kill nerve cells, experts say.

Anxiety has also been linked to the buildup of beta-amyloid, a hallmark of Alzheimer's disease.

People with anxiety are also more likely to make unhealthy choices, such as eating poorly or smoking, the authors say.