Abstract
OBJECTIVE:
To investigate cognitive dysfunction in adult patients with systemic sclerosis (SSc) who had no known clinical neurological manifestations and to relate it with other disease severity parameters.

METHODS:
In the present study, 20 SSc consecutive female patients, who met the 2013 American College of Rheumatology SSc criteria, were compared with 20 healthy age-, gender-, and educational status-matched volunteer hospital workers. Mean age and duration of illness were 41.8 ± 12.52 and 6.9 ± 5.4 years respectively. Mini-Mental State Examination (MMSE), Wechsler Adult Intelligence scale (WAIS-III), and P300 component of event-related potentials (ERPs) were used to evaluate cognitive function in SS subjectively and objectively respectively.

RESULTS:
Sixty-five percent (13 out of 20) of SSc patients had MMSE score < 25, and cognitive impairment. Despite the lack of clinically apparent neurological manifestations, SSc patients had significantly low MMSE score, high Deterioration Index (DI), and prolonged P300 latency compared with that of the control group (P = 0.0001; 0.010 and 0.008 respectively). A significant positive association was found between (DI) and the Medsger severity vascular score (r = 0.518; P = 0.012).There were few differences between limited and diffuse SSc.

CONCLUSIONS:
To our knowledge, few studies highlighted that subclinical cognitive impairment can occur in the course of SSc disease. Early diagnosis of cognitive impairment should be investigated either subjectively (using psychometrics tests as MMSE or WAIS-III) or objectively using P300 evoked related potentials. Medsger severity vascular score seems to be closely related to cognitive impairment.Key points• Cognitive impairment can be associated with Medsger Vascular severity score and the duration of illness.• Further larger studies will be needed to estimate the effect of disease activity on cognitive function, to further delineate the differences between limited and diffuse SSc in this area, and to understand the underlying pathophysiological mechanisms causing cognitive impairment in patients with SSc.• To investigate impaired cognitive function in patients with SSc, even in the absence of clinically apparent neurological and vascular disease.