Objective: To prospectively analyze the association between changes in cognitive function and circulating anticardiolipin antibodies (aCL) over a period of 5 years in patients with systemic lupus erythematosus (SLE).
Methods: Cognitive function was assessed in 51 unselected female SLE patients at baseline and after a mean followup of 64.5 months (range 52-71 months), using standardized tests of cognitive function, i.e., the Wechsler Adult Intelligence Scale-Revised, the Wechsler Memory Scale-Revised, and the California Verbal Learning Test. Circulating IgG, IgA, and IgM aCL and anti-double-stranded DNA (anti-dsDNA) antibody levels were determined by enzyme-linked immunosorbent assay on 4-7 occasions over the same time period. Persistent antibody reactivity was defined as levels more than 2 standard deviations (moderately positive) and more than 5 standard deviations (highly positive) above the mean for normal controls over the duration of the study. Changes in overall cognitive performance and in raw scores on individual cognitive tests were compared in patients who were persistently positive or negative for aCL.
Results: At baseline 11 patients (22%) were cognitively impaired, compared with 7 (14%) at followup. Between 16% and 37% of patients had persistently elevated aCL levels of different isotypes. There was no significant difference in the prevalence of overall cognitive impairment in patients who were persistently positive for aCL compared with those who were not. In contrast, over the period of study, patients who had persistent IgG aCL positivity had a reduction in psychomotor speed, and patients who had persistent IgA aCL positivity had a reduction in conceptual reasoning and executive ability. Similar associations with anti-dsDNA antibodies were not found.
Conclusion: These results suggest that IgG and IgA aCL may be responsible for long-term subtle deterioration in cognitive function in patients with SLE.