The relationship of pain and depression to cognitive function in rheumatoid arthritis patients

Abstract

The purpose of this study was to assess the hypothesis that pain and depression negatively impact the cognitive functioning of individuals with rheumatoid arthritis (RA). One hundred twenty-one community-dwelling RA patients (ages 34-84) completed a battery of cognitive tasks and multiple measures of pain and depression. Structural equation modeling techniques were used to assess the relative contributions of pain, depression, and age to cognitive performance. Individuals who performed poorly on cognitive tasks reported more pain and depression and were older than those individuals who performed well on cognitive tasks. Moreover, high levels of pain were associated with depression. Further analyses revealed that depression mediated the relationship between pain and cognition. That is, when depression was entered into the analyses, the previously significant effects of pain on cognition were no longer found. Interestingly, depression still mediated the pain-cognition relationship even after controlling for age. These findings suggest the importance of both pain and depression for understanding cognitive function in RA and may have important implications for treating this disease.

Cognitive Impairment in Rheumatoid Arthritis: A Systematic Review

“…The majority of participants (59%-100%) in the studies were women; the mean age ranged from 37.2 to 62.9 years (with the SD ranging 2.0-13.5). The mean education level ranged from 1.8 to 15.1 years across 10 studies, with 2 not having provided details on education (34,36) and 3 having provided only prevalence rates (more than 8 years [23] and fewer than 12 years [30,31]). Of the 15 studies, 3 (30,31,33) stated the prevalence of cognitive impairment (30%, 0%, and 31%, respectively), while some of the other studies only reported reduced test scores (34,40) or impairment rates across individual tests (32) or combined groups' rates (42) ( Table 4 (Table 5).…”

“…The inclusion, measurement, and severity of clinical variables varied considerably across studies. The following variables were found to be associated with cognitive function: pain (23,29,31,36,38), disease activity (32,33), fatigue (37), medication (prednisone/steroids [31,40] and MTX [30]), biomarkers (interleukin-6, B cells, and T cells) (34,35,40), and cardiovascular disease risk factors (30). A range of assessment tools was used across studies, prohibiting systematic comparison of clinical profile across samples.…”

“…Further, immune activities such as alterations in dehydroepiandrosterone metabolism also appear to be associated with cognitive impairment, particularly in relation to attention and learning, even when controlling for depression and in sample with mild disease activity (35,40). Medication may also affect cognitive function temporarily at single and accumulative dose levels (22,23,30,31). Finally, pain, fatigue, poor sleep, and depression may be attentional distractions, and in turn affect cognition (23,33,37).…”

“…Medication may also affect cognitive function temporarily at single and accumulative dose levels (22,23,30,31). Finally, pain, fatigue, poor sleep, and depression may be attentional distractions, and in turn affect cognition (23,33,37). How these biologic, clinical and psychological variables interact in the development of cognitive impairment is yet to be determined.…”

“…A commonly prescribed medication for RA is methotrexate (MTX), which is highly effective (19) but which might be associated with cognitive impairment (20), mood changes, and confusion (21). Glucocorticoid therapy has been associated with an immediate impact on memory (22) and a possible cumulative influence on hippocampal function (23). While there seems to be an association between glucocorticoid medication and cognitive impairment in RA (24), the nature of that association has not been determined.…”