Assessment of cognitive function in patients with systemic lupus erythematosus

The spectrum of central nervous system manifestations of systemic lupus erythematosus (SLE) is very broad and has been found to include subtle subclinical cognitive dysfunction which may be detected only by the lengthy process of detailed neuropsychological evaluation. This study reports the value of estimating premorbid intelligence as a simple yet effective means of screening for subclinical cognitive dysfunction. Twenty one female patients with clinically quiescent SLE underwent neuropsychological examination at entry to the study. In all patients, this examination included measurement of full-scale intelligence quotient (IQ), verbal and performance IQ as well as verbal and visual memories. In addition, premorbid intelligence was estimated using the Schonell graded word reading test. Nine patients (43%) gave a history of neuropsychiatric (NP) disease. No difference was identified between the results of the neuropsychological evaluation in these 9 patients and in either the other SLE patients or in age and sex matched control patients. Sixteen patients were re-evaluated 1 year later. A comparison of measured full-scale IQ with the estimated premorbid intelligence identified a subgroup of 3 patients who demonstrated a significant reduction in intelligence. Unlike the other 13 patients, these 3 patients had multiple (3 or more) other features of cognitive impairment.