中文摘要：

组蛋白的甲基化与脱甲基是调控DNA特定基因“开”与“关”的主要分子机制之一，与哺乳动物表观遗传密切相关。研究表明，组蛋白的可逆共价修饰，也是记忆与遗忘的分子调控机制。甲醛作为甲基化供体，参与了组蛋白修饰的关键环节。因此，甲醛代谢失调，可能影响组蛋白甲基化与脱甲基，也影响DNA甲基化与脱甲基，这可能是老年认知损伤的因素之一。

英文摘要：

Histone methylation or demethylation is a process by which methyl groups are transferred onto or taken off the amino acids of histone proteins. In most cases, methylation and demethylation turn the genes in DNA ＂off＂ and ＂on＂, a major process in the epigenetic regulation. The covalent modification of histone is closely related to memory formation and forgetting occurrence. Formaldehyde, a methyl group donor, participates in the modification of histone. This suggests that imbalance of formaldehyde metabolism may interfere with histone methylation and demethylation, which is hypothesized as a risk factor involving age-related cognitive impairment including memory loss.