近日,，國際著名雜志BMJ在線刊登了國外研究人員的最新研究成果“Timing of onset of cognitive decline: results from Whitehall II prospective cohort study，”,，文章中,，研究人員表明人類的大腦衰老可能從45歲就已經(jīng)開始了,。
人們通常認為，大腦認知功能的退化是在五六十歲年老時才會發(fā)生的事情,。但英國一項最新研究顯示,，大腦的衰老可能從45歲就已開始，這個年齡通常被算作中年時期,。
英國倫敦大學學院等機構(gòu)研究人員在新一期《英國醫(yī)學雜志》（BMJ）上報告說,，他們對7000多名英國公務(wù)員進行了長達十年的跟蹤調(diào)查,。在1997年到1999年間研究開始的時候，受試者年齡在45歲到70歲之間,。在研究開始和結(jié)束的時候,，受試者都接受了認知能力測試，對比結(jié)果顯示,，受試者的大腦功能普遍出現(xiàn)了下降,。
令人意外的是，即便是在45歲到49歲年齡組,，大腦功能也出現(xiàn)了下降,，比如在推理功能這一項中，男性和女性都平均下降了3.6%,。而年紀越大的人大腦衰老速度越快,。在65歲到70歲這個年齡組，男性的推理功能在十年間下降了9.6%,，女性稍好一些,，也下降了7.4%。
這些結(jié)果說明,，大腦衰老的時間比人們通常認為的要早,，可能從中年時期就已經(jīng)開始。研究人員說,，如果希望延緩衰老,，避免患老年癡呆等因大腦功能退化而出現(xiàn)的疾病，保持健康的生活方式非常重要,，如盡量不吸煙和加強鍛煉等,。（生物谷Bioon.com）
doi:10.1136/bmj.d7622
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Timing of onset of cognitive decline: results from Whitehall II prospective cohort study
Archana Singh-Manoux, research director123, Mika Kivimaki, professor of social epidemiology2, M Maria Glymour, assistant professor4, Alexis Elbaz, research director56, Claudine Berr, research director78, Klaus P Ebmeier, professor of old age psychiatry9, Jane E Ferrie, senior research fellow10, Aline Dugravot, statistician1
Objectives To estimate 10 year decline in cognitive function from longitudinal data in a middle aged cohort and to examine whether age cohorts can be compared with cross sectional data to infer the effect of age on cognitive decline. Design Prospective cohort study. At study inception in 1985-8, there were 10 308 participants, representing a recruitment rate of 73%. Setting Civil service departments in London, United Kingdom. Participants 5198 men and 2192 women, aged 45-70 at the beginning of cognitive testing in 1997-9. Main outcome measure Tests of memory, reasoning, vocabulary, and phonemic and semantic fluency, assessed three times over 10 years. Results All cognitive scores, except vocabulary, declined in all five age categories (age 45-49, 50-54, 55-59, 60-64, and 65-70 at baseline), with evidence of faster decline in older people. In men, the 10 year decline, shown as change/range of test×100, in reasoning was −3.6% (95% confidence interval −4.1% to −3.0%) in those aged 45-49 at baseline and −9.6% (−10.6% to −8.6%) in those aged 65-70. In women, the corresponding decline was −3.6% (−4.6% to −2.7%) and −7.4% (−9.1% to −5.7%). Comparisons of longitudinal and cross sectional effects of age suggest that the latter overestimate decline in women because of cohort differences in education. For example, in women aged 45-49 the longitudinal analysis showed reasoning to have declined by −3.6% (−4.5% to −2.8%) but the cross sectional effects suggested a decline of −11.4% (−14.0% to −8.9%). Conclusions Cognitive decline is already evident in middle age (age 45-49).
