Archief Roodbont

HOME | SUBSCRIBE | SEARCH | CURRENT ISSUE | PAST ISSUES | COLLECTIONS | HELP

Please sign in for full text and personal services

Previous Volume 354:2764-2772 June 29, 2006 Number 26 Next

Jennifer A. McMahon, Ph.D., Timothy J. Green, Ph.D., C. Murray Skeaff, Ph.D., Robert G. Knight, Ph.D., Jim I. Mann, Ph.D., and Sheila M. Williams, D.Sc.

Full Text PDF PDA Full Text PowerPoint Slide Set CME Exam Translated Abstracts Deutsch Español Français Italiano Editorial by Clarke, R. Add to Personal Archive Add to Citation Manager Notify a Friend E-mail When Cited E-mail When Letters Appear Find Similar Articles PubMed Citation

ABSTRACT

Background The results of observational studies suggest that plasma homocysteine concentrations are inversely related to cognitive function in older people. Our objective was to test the hypothesis that lowering the plasma homocysteine concentration improves cognitive function in healthy older people.

Methods We conducted a two-year, double-blind, placebo-controlled, randomized clinical trial involving 276 healthy participants, 65 years of age or older, with plasma homocysteine concentrations of at least 13 µmol per liter. Homocysteine-lowering treatment was a daily supplement containing folate (1000 µg) and vitamins B₁₂ (500 µg) and B₆ (10 mg). Tests of cognition were conducted at baseline and after one and two years of treatment. Treatment effects were adjusted for baseline values, sex, and education.

Results On average, during the course of the study, the plasma homocysteine concentration was 4.36 µmol per liter (95 percent confidence interval, 3.81 to 4.91 µmol per liter) lower in the vitamin group than in the placebo group (P<0.001). Overall, there were no significant differences between the vitamin and placebo groups in the scores on tests of cognition.

Conclusions The results of this trial do not support the hypothesis that homocysteine lowering with B vitamins improves cognitive performance. (Australian Clinical Trials registry number, ACTR NO 12605000030673.)

Source Information

From the Departments of Human Nutrition (J.A.M., T.J.G., C.M.S., J.I.M.), Psychology (R.G.K.), and Preventive and Social Medicine (S.M.W.), University of Otago, Dunedin, New Zealand.

Address reprint requests to Dr. Skeaff at the Department of Human Nutrition, University of Otago, P.O. Box 56, Dunedin, New Zealand, or at murray.skeaff@stonebow.otago.ac.nz.

Full Text of this Article

This article has been cited by other articles:

• (2006). Homocysteine-Lowering and Cognitive Performance. Journal Watch (General) 2006: 2-2 [Full Text]
• Clarke, R. (2006). Vitamin B12, Folic Acid, and the Prevention of Dementia. NEJM 354: 2817-2819 [Full Text]

HOME | SUBSCRIBE | SEARCH | CURRENT ISSUE | PAST ISSUES | COLLECTIONS | HELP Comments and questions? Please contact us. The New England Journal of Medicine is owned, published, and copyrighted © 2006 Massachusetts Medical Society. All rights reserved.

Human Evolution Timeline Evolution Home Page Mutations Transitions Questions

500,000-200,000 Years ago Homo sapiens (archaic) are also known as Homo heidelbergensis. Remains from this space have been found in a variety of places starting from Germany to Bodo, Africa, and even in Jinniushan, Asia (1). Their brain size increased and their skull encasing also became more rounded than the skull of the Homo erectus(2). The skeleton and teeth are generally less thick and dense, but there are still large brow ridges present(3). They also had a much steeper forehead than previous species, which hints that the brain itself had more emphasis on the forebrain (1). This is a very interesting observation for this sector of the brain is responsible for planning and reasoning, movements of limbs, speech, as well as social conduct, which modern day humans are much more advanced in (1). The social life of the Homo sapien (archaic) is still quite vague for not many clues have been found at this point. The advancement of tools was seen, especially the presence of the hand axe(4). Weapons were also found, which shows that the hunting style of life was more prevalent, and meat was a higher percent of their diet. Hopefully, more clues will show up as additional remains are found. Homo sapien (archaic) skull side view Homo sapien (archaic) skull front view Homo sapien (archaic) skull Ardipithecus ramidus Australopithecus anamensis Australopithecus afarnensis Australopithecus africanus Australopithecus robustus Australopithecus boisei Homo habilis Homo erectus Homo sapiens neanderthalensis Homo sapiens (modern) References: 1. Park, Michael A., 1999, Biological Anthrolpology: Second Edition, Mayfield Publishing Company, Mountain View California, 412 p. 2. Public Broadcasting Station, 1998, Human Evolution, http://www.pbs.org/wgbh/aso/tryit/evolution/ (November 30, 2001) 3. Foley, Jim, July 31, 2001, Hominid Species, http://www.talkorigins.org/faqs/homs/species.html (November 29, 2001) 4. Washington State Univesity, n.d., Homo sapiens: Earliest Forms of Our Own Species, http://www.wsu.edu:8001/vwsu/gened/learn-modules/top_longfor/timeline/h-sapiens/h-sapiens-a.html (December 5, 2001)