A decreased expression of several components of the mitochondrial respiratory chain complexes I (Ndufa1, Ndufa2, Ndufa3, Ndufa5, Ndufa8, Ndufa9, Ndufb2, Ndufb3, Ndufb7, Ndufc2, Ndufs1, Ndufs2, Ndufs3, Ndufs4, Ndufs8, Ndufs7, Ndufv1, Ndufv2), II (Sdha, Sdhb, Sdhc), III (Uqcrc1, Uqcrc2, Uqcr10, Uqcr11, Uqcrfs1, Uqcrb, Uqcrh, Uqcrq), IV (Cox4i1, Cox5a, Cox5b, Cox6a1, Cox7a2, Cox7b, Cox10, Cox11, Cox15) and V (Atp5a1, Atp5b, Atp1b1, Atp5c1, Atp5d, Atp5g3, Atp5j, Atp5j2, Atp5o) was also found in the hippocampus and/or retina of Tg2576 AD mice. The gene discussed is NDUFS2; the disease is Alzheimer disease.