ObjectiveTo review the clinical, psychometric, laboratory, and radiologic findings of 6 patients with Sneddon's syndrome (SS) who presented with cognitive dysfunction rather than stroke.Design and MethodsCase series. All patients fulfilled were diagnosed as SS based on the co-occurrence of livedo racemosa and neurologic disease. Patients presenting with clinical stroke were excluded.ResultsPatients presented with cognitive complaints at an early age and all noted skin lesions from 6 months to 10 years before onset of cognitive symptoms. Associated systemic disorders included hypertension and seizures. Laboratory evidence of a hypercoagulable condition was identified in 4 of 6 cases. Brain MRI scans demonstrated atrophy, especially in parieto-occipital regions and cerebral blood flow on brain SPECT scan was reduced in a similar distribution.ConclusionPatients with SS can develop dementia without antecedent clinical stroke. While the specific pathogenic mechanism of dementia in SS remains speculative, the disease predominantly injures brain tissue in vascular “watershed” territories.