A 75-year-old patient was evaluated for dementia. His past medical history included an ischaemic cardiomyopathy treated with aspirin daily. His neurological examination showed mild ataxia syndrome and central deafness. The neuropsychological examination did not suggest Alzheimer's disease. No specific aetiology was found from biological investigations, but MRI scans revealed a superficial siderosis, which was further confirmed with CSF exams. This case highlights the interest of MRI with echo-gradient-T2 weighted sequences in patients investigated for memory disorders. Once the diagnosis is known, specific preventive measures have to be taken: searching for a treatable source of bleeding and the interruption of antiplatelet aggregation or anticoagulant treatments.