MRI - AIDS-dementia complex: This 43-year-old man with a history of advanced AIDS presented with a gradual decline in motivation and memory. Examination showed a mini-mental status examination score of 26/30. Detailed neuropsychological testing revealed marked impairment in multiple cognitive areas. Cerebrospinal fluid analysis was unremarkable. The T1-weighted axial MR image shows no focal lesions, but there is ventricular dilatation and sulcal predominance atypical for age, consistent with the AIDS-dementia complex.