# Differential associations of non-chronic and chronic pain with dementia risk: insights from a cohort study

## TL;DR

Chronic pain, especially widespread pain, is linked to a higher risk of dementia compared to non-chronic pain, suggesting that pain duration and distribution may influence dementia development.

## Contribution

This study identifies distinct associations between chronic and non-chronic pain with dementia risk using a large cohort.

## Key findings

- Chronic widespread pain is associated with a significantly higher dementia risk compared to no pain.
- Non-chronic widespread pain does not show a significant association with dementia risk.
- Dementia risk increases with the number of chronic pain sites, but not consistently for non-chronic pain.

## Abstract

An association between pain and dementia risk has been increasingly recognized; however, it remains unclear how non-chronic and chronic pain may differentially influence this association. This study aimed to compare the associations of non-chronic and chronic pain with dementia risk.

We analyzed data from 493,491 participants in the UK Biobank, with follow-up from baseline until the first occurrence of dementia, death, or the end of the study period (November 11, 2021). Pain was assessed at baseline and classified into four categories: chronic (>3 months) or non-chronic (past 4 weeks), and regional (specific sites) or widespread (all over body). The outcome was incident dementia, ascertained via the UK Biobank algorithm linking hospital admissions data, death register data and self-reports. Cox proportional hazards models were employed, adjusted for age, sex, race, education, socioeconomic status (Townsend deprivation index), and comorbidities (hypertension, heart disease, diabetes, stroke, lung disease and cancer).

Over a median follow-up of 12.7 years (interquartile range [IQR]: 11.9–13.4), 7,449 participants developed dementia. Compared with individuals without pain, chronic regional and chronic widespread pain were associated with higher dementia risks (adjusted hazard ratios [aHRs]: 1.26 [95% CI: 1.19 to 1.33] and 1.95 [1.67 to 2.26]; incidence rate differences: 0.40 [0.34 to 0.46] and 1.45 [1.12 to 1.79] per 1,000 person-years, respectively). Non-chronic regional pain showed a modest increase in risk (aHR: 1.18 [1.10 to 1.27]; incidence rate difference: 0.04 [−0.03 to 0.12]), while non-chronic widespread pain was not significantly associated (aHR: 1.16 [0.76 to 1.77]; incidence rate difference: 0.20 [−0.29 to 0.69]). Dementia risk increased with the number of chronic pain sites, but no consistent trend was observed for non-chronic pain.

Chronic pain, especially when widespread, is associated with higher dementia risk, while non-chronic pain shows weaker or no associations. These findings suggest that both the duration and distribution of pain may play a role in dementia development and highlight the need for further research to explore underlying mechanisms.