An approach to the evaluation of dementia in adults related to pediatric metabolic and degenerative diseases is reviewed from the Department of Neurology, University Medical Center, Maywood, IL. A list of 17 neurodegenerative disorders that ordinarily occur in childhood but may be present in adults includes adrenoleukodystrophy, metachromatic leukodystrophy, Krabbe’s disease, Alexander’s disease, Lafora’s disease, Kufs’ disease, mucopolysaccharidosis, Gaucher’s type 1, Niemann-Pick disease, and gangliosidosis 1 and 2. Diagnosis is important for genetic counseling and some are treatable. A history of myoclonus suggests Kufs’ disease, Lafora’s disease, and mitrochondrial disorders. Easy tanning on sun exposure suggests adrenoleukodystrophy. Bone pain occurs with Gaucher’s disease. Extrapyramidal symptoms suggest gangliosidosis. Muscle weakness is seen with gangliosidosis and mitochondrial disorders. Depressed deep tendon reflexes may occur with metachromatic leukodystrophy, adrenoleukodystrophy and gangliosidosis. Organomegaly is present in Gaucher’s disease, Niemann-Pick disease and mucopolysaccharidosis. Macrocephaly can occur with Alexander’s disease and metachromatic leukodystrophy. Special studies to be considered in young adults with idiopathic dementia include: 1) very long-chain fatty acids (adrenoleukodystrophy); 2) mucopolysaccharide screen; 3) arylsulfatase A (metachromatic leukodystrophy); 4) bone marrow for foam cells (Niemann-Pick disease); 5) copper and ceruloplasmin (Wilson’s disease). [1]