It has long been known that people with mild cognitive impairment are at increased risk of developing Alzheimer’s disease, but a new study warns the risk increases significantly if they suffer from anxiety, as well.
The findings, published in The American Journal of Geriatric Psychiatry, suggest that anxiety accelerates cognitive decline in people with mild cognitive impairment (MCI), meaning they may develop Alzheimer’s at a much faster pace and much earlier than people without coexisting anxiety.
According to the Alzheimer’s Association, an estimated 10-20 percent of people aged 65 and older have MCI, which is characterized by changes in cognitive function — such as memory and thinking skills — that can be noticed by others or the individual experiencing the changes, but that are not severe enough to disrupt day-to-day life.
Although MCI significantly increases someone’s risk of developing Alzheimer’s, not everyone with MCI will get worse and develop the disease. If researchers could identify those people who will end up progressing to Alzheimer’s, it may be possible to intervene at an earlier stage. In the future, for example, researchers might seek to develop drugs to prevent the progression of MCI to dementia.
A growing body of literature has identified late-life depression as a significant risk marker for Alzheimer’s. More recently, studies have also found that anxiety may be linked with the development of Alzheimer’s. However, anxiety and depression are conflated in much of the research, making it difficult to discern the independent effects of anxiety.
In this latest study — led by principal investigator Dr. Linda Mah, an assistant professor in the Department of Psychiatry at the University of Toronto and a clinician-scientist at the Baycrest Health Sciences’ Rotman Research Institute, both in Canada — researchers sought to isolate anxiety as a potentially significant risk marker for Alzheimer’s in people diagnosed with MCI to gain a clearer picture of just how damaging anxiety symptoms (independent of depression) can be on cognition and brain structure over a period of time.
Anxiety in MCI patients increased risk of Alzheimer’s by up to 135%
Over an average of 3 years, the team analyzed 376 patients aged 55 to 91 years-old with amnestic MCI — characterized by the inability to recall important information, such as appointments, recent events or conversations — who were a part of the Alzheimer’s Disease Neuroimaging Initiative (ADNI). Every 6 months, the researchers assessed participants’ levels of anxiety and depression, as well as changes in cognitive functioning and brain structure.
Results of the analysis revealed that participants who had anxiety experienced a faster decline in cognitive function than those without anxiety, and that the speed of decline increased with the severity of anxiety. MCI patients with mild anxiety had a 33% increased risk of Alzheimer’s, moderate anxiety was linked to a 78% Alzheimer’s risk, while severe anxiety increased Alzheimer’s risk by 135%.
What’s more, the team found that participants who reported symptoms of anxiety at any point over the study period showed higher levels of brain atrophy – brain shrinkage – in the medial temporal lobe regions, which are crucial for creating memories. Atrophy in these brain regions has been implicated in Alzheimer’s. The researchers also point out that all participants had low scores on the depression scale, suggesting that their findings were not a result of clinical depression.
MCI patients should receive routine anxiety screening, stress management interventions
This study yielded important evidence that anxiety is a “predictive factor” of whether an individual with MCI will convert to Alzheimer’s or not, says Dr. Mah. Studies have shown that anxiety in MCI is associated with abnormal concentrations of plasma amyloid protein levels and T-tau proteins in cerebrospinal fluid, which are biomarkers of Alzheimer’s. Depression and chronic stress have also been linked to smaller hippocampal volume and increased risk of dementia.
Importantly, the findings show clearly for the first time that anxiety symptoms in individuals diagnosed with MCI increase the risk of a speedier decline in cognitive functions – independent of the potentially confounding effects of depression. The distinction is important because anxiety has historically tended to be subsumed under the rubric of depression in psychiatry. While depression is routinely screened for in assessment and follow-up of memory clinic patients, anxiety is not part of routine screening.
“Our findings suggest that clinicians should routinely screen for anxiety in people who have memory problems because anxiety signals that these people are at greater risk for developing Alzheimer’s,” says Dr. Mah. In addition to screening, she says people with MCI should also be offered strategies that help treat or manage anxiety. “While there is no published evidence to demonstrate whether drug treatments used in psychiatry for treating anxiety would be helpful in managing anxiety symptoms in people with MCI or in reducing their risk of conversion to Alzheimer’s, we think that at the very least behavioral stress management programs could be recommended.”
“In particular,” she adds, “there has been research on the use of mindfulness-based stress reduction in treating anxiety and other psychiatric symptoms in Alzheimer’s, and this is showing promise.”