Quantitation of GFAP+ cells revealed no age- or cognitive decline-associated changes in astrocyte density (mean ± S.E.M) in DG (astrocytes/100 μm2: adult: 60 ± 2.7, aged intact: 58 ± 1.1, aged impaired: 61 ± 1.8), CA3 (astrocytes/100 μm2: adult: 74 ± 2.4, aged intact: 76 ± 3.2, aged impaired: 72 ± 1.2), or CA1 (astrocytes/100 μm2: adult: 56 ± 1.3, aged intact: 54 ± 1.5, aged impaired: 56 ± 2.1). The gene discussed is GFAP; the disease is Mental deterioration.