Chronic pain in osteoarthritis of the hip is associated with selective cognitive impairment

Abstract

Introduction: Chronic pain of various origin is known to be associated with selective cognitive impairment. Osteoarthritis (OA) of the hip is one of the leading causes of chronic pain in the adult population, but its association with cognitive performance has not been evaluated. Here, we investigate the effect of chronic pain due to unilateral OA of one hip and no further source of chronic pain on cognitive performance.

Materials and methods: A neuropsychological test battery, consisting of the Mini-Mental State Examination, Rey-Osterrieth complex figure test, Rivermead behavioural memory test, d2 test of attention, and F-A-S test was applied in 148 patients and 82 healthy pain-free control individuals. The influence of potentially confounding factors such as depression and anxiety was examined.

Results: Patients with OA of the hip showed decreased performance in specific neuropsychological tests. Performance in verbal and visual short-term and long-term memory and selective attention tests was significantly poorer compared to healthy controls. Whereas the executive functions "updating", "set shifting", "response inhibition" and "reflection" appear intact, "problem solving" and "planning" were impaired. None of the confounders showed any influence on cognitive performance in both study groups.

Conclusion: We conclude that chronic pain secondary to end-stage hip OA is associated with selective cognitive impairment. Future studies are required to investigate the effect of total hip arthroplasty on cognitive performance.

Keywords: Chronic pain; Cognitive impairment; Hip osteoarthritis; Hip replacement.

Fig. 1

The memory A and memory quotient B scores of the Rey–Osterrieth complex figure test (ROCFT) reveal a significant impairment of the memory in the chronic pain group (CPG) as compared to the control group (CG). **p < 0.001

Fig. 2

The Rivermead behavioral memory test (RBMT) reveals a significant impairment of behavioral memory in the chronic pain group (CPG) as compared to the control group (CG) in both recall (A) and delayed recall (B) qualities. **p < 0.001

Fig. 3

The d2 test reveals significant differences in the total marks (A), total marks minus mistakes (D) and concentration performance (E) indicating an impairment of selective attention and executive function in the chronic pain group (CPG) as compared to the control group (CG). Omit mistakes (B) and wrong marks (C) displayed no significant differences. **p < 0.001

Fig. 4

A, B, C The Trail Making Test (TMT) does not reveal differences in the executive functions set shifting and updating between the chronic pain group (CPG) and the control group (CG). These functions appear to be unaffected by hip OA

Fig. 5

The verbal fluency test F-A-S does not reveal any differences in the executive functions set shifting and updating between the chronic pain group (CPG) and the control group (CG)