Both chronic pain and analgesic use have been suggested to increase the risk of parkinsonism and dementia. We, therefore, investigated whether chronic pain, analgesic use alone, or their combination is associated with increased incident risk of these conditions.
Participants (n=355,709, mean age 56.51, 48.40% male) free of parkinsonism and dementia, reported their chronic musculoskeletal pain lasting ≥3 months and their use of common analgesics, including paracetamol, non-steroidal anti-inflammatory drugs (NSAIDs), opioids, and antidepressants. The incidence of all-cause parkinsonism, Parkinson's disease (PD), all-cause dementia, and Alzheimer's disease (AD) was recorded. Cox regression was used for the analyses.
Over a 13-year follow-up, 2,281 cases developed all-cause parkinsonism, 2,035 had PD, 4,778 developed all-cause dementia, and 2,052 had AD. In multivariable analyses, as compared to participants without chronic pain and analgesic use, chronic pain, analgesic use only and their combination had a higher risk of incident all-cause parkinsonism (Chronic pain only: hazard ratios (HRs) ranging from 1.13-1.21; Analgesic use only: 1.15-1.76; Combination: 1.21-2.13) and dementia (Chronic pain only: HRs 1.14-1.17; Analgesic use only: 1.18-1.92; Combination: 1.38-2.41) with individuals having the highest risk in those with both chronic pain and analgesic use. Similar patterns were observed for PD and AD risk.
While chronic pain, or analgesic use alone is associated with a higher risk of incident parkinsonism and dementia those with both had the highest risk. The mechanism for this warrants further investigation as it may inform approaches to reducing the risk of these conditions.