Non-criteria anti-phospholipid antibodies and cognitive impairment in SLE

The pathogenesis of cognitive impairment (CI) in patients with systemic lupus erythematosus (SLE) is unknown. Anti-phospholipid antibodies (APL) have been implicated. The APL which have been evaluated have variably included anti-cardiolipin (ACL) antibodies, lupus anticoagulant (LAC), and antibodies to beta-2 glycoprotein I (β2GPI). Few studies have examined other APL (so-called non-criteria APL). We evaluated the association of CI with a broad spectrum of non-criteria APL. Subjects meeting SLE classification criteria were recruited from three different patient populations. Cognitive function was assessed with the Automated Neuropsychologic Assessment Metrics (ANAM), a validated computer-based assessment tool. The total throughput score (TTS = number of correct responses/time) was used as the primary outcome measure. The following APL of all three isotypes were assessed by ELISA using standardized techniques: anti-β2GPI, anti-phosphatidyl ethanolamine (aPE), anti-phosphatidyl choline (aPC), anti-phosphatidyl inositol (aPI), anti-phosphatidyl serine (aPS), anti-phosphatidyl glycerol (aPG), anti-phosphatidic acid (aPA). Fifty-seven (57) patients were evaluated. Of the 57, 12 had definite CI (>1.5 SD below the mean of an age-, sex-, and race-matched RA population). The two groups were significantly different with regard to age, ethnicity, and family income. There was no significant difference between groups with regard to the presence of any non-criteria APL. When titers of specific non-criteria APL were compared with TTS, no significant correlations were found. Using multiple linear regression and adjusting for relevant covariates including age, ethnicity, and family income, neither the presence nor the titer of any non-criteria APL significantly influenced TTS. In this cross-sectional study, non-criteria APL were not associated with CI.