International Psychogeriatrics

Research Article

Homocysteine levels and dementia risk in Yoruba and African Americans

Hugh C. Hendriea1a2a3 c1, Olusegun Baiyewua4, Kathleen A. Lanea5, Christianna Purnella2, Sujuan Gaoa5, Ann Hakea6, Adesola Ogunniyia7, Oye Gurejea4, Frederick W. Unverzagta3, Jill Murrella8, Mark A. Deega9 and Kathleen Halla3

a1 Indiana University Center for Aging Research, Indianapolis, Indiana, USA

a2 Regenstrief Institute Inc., Indianapolis, Indiana, USA

a3 Department of Psychiatry, Indiana University School of Medicine, Indianapolis, Indiana, USA

a4 Department of Psychiatry, College of Medicine, University of Ibadan, Nigeria

a5 Department of Biostatistics, Indiana University School of Medicine, Indianapolis, Indiana, USA

a6 Department of Neurology, Indiana University School of Medicine, Indianapolis, Indiana, USA

a7 Department of Medicine, College of Medicine, University of Ibadan, Nigeria

a8 Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA

a9 Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana, USA

ABSTRACT

Background: High levels of homocysteine have been associated with increased risk for dementia although results have been inconsistent. There are no reported studies from the developing world including Africa.

Methods: In this longitudinal study of two community-dwelling cohorts of elderly Yoruba and African Americans, levels of homocysteine, vitamin B12 and folate were measured from blood samples taken in 2001. These levels were compared in two groups, participants who developed incident dementia in the follow-up until 2009 (59 Yoruba and 101 African Americans) and participants who were diagnosed as cognitively normal or in the good performance category at their last follow-up (760 Yoruba and 811 African Americans). Homocysteine levels were divided into quartiles for each site.

Results: After adjusting for age, education, possession of ApoE, smoking, and time of enrollment the higher quartiles of homocysteine were associated with a non-significant increase in dementia risk in the Yoruba (homocysteine quartile 4 vs. 1 OR: 2.19, 95% CI 0.95–5.07, p = 0.066). For the African Americans, there was a similar but non-significant relationship between higher homocysteine levels and dementia risk. There were no significant relationships between levels of vitamin B12 and folate and incident dementia in either site although folate levels were lower and vitamin B12 levers were higher in the Yoruba than in the African Americans.

Conclusions: Increased homocysteine levels were associated with a similar but non-significant increase in dementia risk for both Yoruba and African Americans despite significant differences in folate levels between the two sites.

(Received March 24 2013)

(Reviewed May 16 2013)

(Revised June 19 2013)

(Accepted July 01 2013)

(Online publication July 30 2013)

Key words:

  • dementia;
  • Alzheimer’s disease;
  • homocysteine;
  • African Americans;
  • Yoruba

Correspondence

c1 Correspondence should be addressed to: Hugh C. Hendrie, MB, ChB, DSc, Indiana University Center for Aging Research, 410 W 10th St., Suite 2000 Indianapolis, IN 46202, USA. Phone: +(317)-423-5591; Fax: +(317)-423-5695. Email: hhendri@iupui.edu.