Noteworthy, NNI-351, a compound with only a proliferative phenotype (Ki67+ cells greater than DS-vehicle, data not shown), reduced hyperactivity, but was ineffective in reversing memory deficits in aging and DS models, suggesting that maturation and survival of adult-born neural cells are necessary for cognitive improvements in aging and neurodegenerative disease. The gene discussed is MKI67; the disease is neurodegenerative disease.