Does Chronic Anxiety Increase Dementia Risk in the Elderly?

Anxiety can lead to cognitive deterioration in certain individuals.

Posted Jun 11, 2015

Generalized anxiety disorder (GAD) is a common illness in the elderly. It is characterized by excessive worrying that is difficult to control. In addition, the individual experiences several of the following symptoms: restlessness, fatigue, poor ability to focus, muscle tension, and sleep difficulties. The symptoms lead to distress in many aspects of the person's life, and the illness is usually chronic. Some older individuals have suffered from this disorder most of their lives, while others develop GAD in mid or late life. 

Even though GAD is common in the elderly, most people with the disorder do not see psychiatrists. Rather, GAD is often treated by primary care doctors either alone or in conjunction with counselors. This disorder does respond to pharmacotherapies and/or psychotherapies, and its prevalence in the elderly may be a factor contributing to the increased use of benzodiazepines (anti-anxiety medications) in the elderly, as discussed in a prior post.             

Over the last several years, research studies have demonstrated a possible interaction between anxiety and the development of Alzheimer's disease. A recent paper published in JAMA Psychiatry by Robert Pietrzak and colleagues provides strong evidence for such a relationship.

These investigators studied 300 healthy seniors for 4.5 years. Knowing that a substance called beta-amyloid accumulates in the brain years before the symptoms of Alzheimer's disease become clinically apparent, they used a specialized type of brain scan to measure amyloid accumulation in the brain of each participant at the time of entry into the study. Half of the participants had evidence of amyloid accumulation in their brains and half did not. They also evaluated each participant for symptoms of anxiety, using a research scale that assesses symptoms during the week prior to the evaluation. Those who demonstrate high degrees of anxiety on this scale are likely to have an anxiety disorder. 

During the subsequent 54 months of the study, each person underwent a series of neuropsychological tests at predetermined intervals. The investigators analyzed their data by dividing the participants into 4 groups based on brain amyloid burden and anxiety symptoms at the start of the study:  those with low anxiety and low amyloid, those with low anxiety and high amyloid, those with high anxiety and low amyloid, and those with high anxiety and high amyloid.

Over the course of the study, people with high anxiety and high amyloid showed significant declines in tasks involving verbal memory, language, and executive function. This change in performance over time was substantially different from the changes in performance in the other three groups, including the group with high anxiety but low levels of amyloid. This suggests that there is an interaction between anxiety and accumulating amyloid. 

Why anxiety affects the rate of cognitive deterioration in persons with accumulating amyloid is unknown. However, symptoms of anxiety respond to treatment. In contrast, no treatment is currently available to prevent Alzheimer's disease. In addition to helping alleviate the symptoms of anxiety, there is a possibility that successful treatment of GAD could slow the rate of cognitive deterioration in persons with accumulating amyloid. Future research will be needed to determine if this hypothesis is correct.

The Pietrzak and colleagues’ study adds to a growing literature indicating that stressful conditions, including poor sleep, may play a role in the onset and progression of Alzheimer’s disease. Furthermore, there is evidence that certain antidepressant medications that are helpful for treating anxiety as well as depression may diminish the production and accumulation of beta-amyloid in the brain; this effect appears to be independent of the drugs’ efficacious effects on psychiatric symptoms. On the other hand, it is becoming increasingly clear that benzodiazepines, which are also used to treat anxiety, have significant risks in the elderly and likely are overprescribed by physicians.

Untreated, GAD can lead to substantial distress and may increase the risk of developing Alzheimer's disease. We believe that it is important for primary care doctors to routinely screen patients for GAD (as well as for depression). Should one or both of these treatable disorders be present, appropriate treatment should be initiated. Such treatment should diminish the symptoms of GAD, and the possibility exists that this may delay the onset of Alzheimer's disease. This latter possibility will be tested more directly in future studies.

This post was written by Eugene Rubin MD, PhD and Charles Zorumski MD.