Reversible dementia and polyneuropathy in an elderly woman: a case of late onset systemic lupus erythematosus. We report the case of a 76-year-old woman with undiagnosed systemic lupus erythematosus. She presented with severe dementia. She was given prednisolone 20 mg daily with dramatic improvement occurring within one month. Electrophysiological study showed evidence of axonal neuropathy.