Anxiety’s Long-Term Impact on Dementia Development

In a recent study published in the Journal of the American Geriatrics Society, a group of researchers assessed the longitudinal relationship between chronic, resolved, and new onset anxiety and the risk of all-cause dementia (Progressive cognitive decline affecting memory and thinking).

Study: The effect of anxiety on all-cause dementia: A longitudinal analysis from the Hunter Community Study. Image Credit: simona pilolla 2/Shutterstock.com

Background 

Globally, over 55 million people lived with dementia in 2020, a number projected to rise to 78 million by 2030 and 139 million by 2050. The global cost of dementia was estimated at the United States (US)$ 1.3 trillion in 2019, projected to reach US$ 2.8 trillion by 2050.

Dementia was the seventh major cause of death worldwide and the second in high-income countries in 2020. With the increasing economic and social burden of dementia, prevention efforts focus on modifiable risk factors, including anxiety.

Further research is needed to clarify the impact of chronicity and timing of anxiety on dementia risk to develop targeted prevention strategies.

About the study 

The present study used longitudinal Hunter Community Study (HCS) data. Participants aged 55 to 85 from New South Wales (NSW), Newcastle, Australia, were randomly selected and recruited between December (2004 - 2007).

Exclusions included non-English speakers, aged care facility residents, and those with baseline dementia or missing data, resulting in 2132 participants.

Demographics and health data (alcohol intake, smoking, hypertension (Chronic high blood pressure), diabetes (Condition with high blood sugar levels), cardiovascular (Condition with high blood sugar levels) and cerebrovascular (Disorders affecting blood flow to the brain) disease) were collected via questionnaires at baseline.

Depression was measured using the Center for Epidemiologic Studies Depression Scale (CES-D score), with scores of 16 or above indicating depression. Anxiety was assessed using the Kessler Psychological Distress Scale (K10) at baseline and first follow-up, categorizing it as resolved, chronic, or new.

Incident all-cause dementia was identified using International Classification of Disease 10 (ICD 10) codes from linked data sources, including disease registers and the national death index, with the earliest recorded diagnosis date used.

Statistical analysis compared the characteristics of those who developed dementia versus those who did not, using t-tests and Chi-square tests. Confounders were adjusted for using a directed acyclic graph (DAG).

The Fine and Gray regression model estimated the subdistribution hazard of anxiety on dementia risk, with death as a competing event. Sensitivity analyses addressed missing data and the severity of anxiety. Statistical analyses were performed using SAS software (version 9.4).

Study results 

The HCS initially included 3,318 participants at wave 1. After excluding those with dementia at baseline and those lacking age and K10 information, 3,163 participants were eligible. From these, 1,031 did not have K10 data at wave 2, leaving 2,132 participants (53% female, 47% male) in the study.

The mean age of participants was 76 years (SD 7 years), with 21% experiencing anxiety at baseline. Over a mean follow-up of 10 years (SD 1.6), 64 participants (3%) developed dementia, and 151 (7%) died, with the average onset of dementia being ten years (SD 1.7).

Missing participants had lower education levels and higher rates of alcohol consumption, smoking, hypertension, diabetes, cardiovascular and cerebrovascular disease, baseline anxiety, and depression.

Chronic anxiety was linked with an increased risk of all-cause dementia in both unadjusted and adjusted models. New anxiety at wave two was also linked to a higher dementia risk. However, resolved anxiety did not significantly affect dementia risk.

Age-specific analyses showed that participants younger than 70 with chronic anxiety had a higher dementia risk, and those under 70 with new anxiety at follow-up also had an increased risk. Anxiety did not significantly associated with dementia risk in other age groups.

In sensitivity analyses, excluding participants censored within the first five years maintained the increased dementia risk for chronic and new anxiety at wave 2, while baseline-only anxiety was not significant.

Analyses addressing missing data through multiple imputations and observed cases revealed similar but attenuated effects of baseline anxiety on dementia risk.

There was a graded association with anxiety severity: participants with moderate anxiety (K10 scores 16-30) and severe anxiety (scores >30) showed increased hazard ratios for dementia, although these estimates were not statistically significant.

Conclusions 

To summarize, this study is the first to explore the relationship between resolved, chronic, and new onset anxiety and all-cause dementia risk longitudinally.

Among 2,132 cognitively healthy participants, chronic and new anxiety were linked to an increased risk of dementia, especially in those under 70, while resolved anxiety showed no significant risk.

Sensitivity analyses confirmed the findings, suggesting that the association is unrelated to reverse causality. Findings highlight anxiety as a modifiable risk factor, emphasizing the importance of managing anxiety to reduce dementia risk in later life potentially.