Primary Sjogren’s syndrome: cognitive symptoms, mood, and cognitive performance

Primary Sjogren’s syndrome (PSS) is a chronic systemic autoimmune disease characterized by exocrine gland inflammation and symptoms of oral and ocular dryness. Females are affected more frequently than males in a ratio of nine to one with onset of symptoms typically in the fifth decade of life. In addition to the cardinal symptoms of oral and ocular dryness, patients also commonly experience fatigue, pain and cognitive symptoms. The prevalence of depression in PSS is between 30 to 50%. (1,2) Cognitive dysfunction, often experienced as problems with memory, attention or information processing is disturbing to patients and poses a vexing issue for clinicians as a variety of factors can underlie these symptoms. While cognitive dysfunction is commonly experienced and psychological distress is frequent, published data regarding cognitive function in PSS is sparse. Patients with mild cognitive impairment are often not classified as CNS Sjogren’s, hence the relationship of cognitive dysfunction to pathologic processes specific to PSS, has not been adequately investigated. (3–5) Cognitive deficits can arise from depression, however both cognitive and affective disorders could also be the result of immune mediated brain dysfunction, and hence patients with affective and cognitive complaints present difficult therapeutic challenges. Data on the neuropsychological function of patients with PSS is difficult to interpret due to differences in patient selection between centers and lack of standardized cognitive assessment. (3,6) Frontal and subcortical brain involvement characterized by shortened attention span, poor concentration, memory deficits and cognitive slowness, has been reported in patients referred to tertiary care centers, many of whom had overt central nervous system manifestations and depression. (6,7) To date, there is no data in PSS regarding the relationship of specific neuropsychological outcomes to measures of pain or depression. The aim of this study was to investigate the relationship between perceived cognitive dysfunction, depression and objective cognitive impairment in PSS patients who had no history of central nervous system disorder other than cognitive complaints. We investigated the validity of patient- reported cognitive problems by comparing self-reports with the results of objective tests, and we explored the contribution of pain and depression to objectively measured cognitive abilities.