Associations between Serum Omega-3 Fatty Acid Levels and Cognitive Functions among Community-Dwelling Octogenarians in Okinawa, Japan: The KOCOA Study

Article type: Research Article

Authors: Nishihira, Junko^{a; *} | Tokashiki, Takashi^a | Higashiuesato, Yasushi^b | Willcox, Donald Craig^{c; d} | Mattek, Nora^e | Shinto, Lynne^e | Ohya, Yusuke^a | Dodge, Hiroko H.^{e; f; *}

Affiliations: [a] Department of Cardiovascular Medicine, Nephrology and Neurology, University of the Ryukyus, Okinawa, Japan | [b] Clinical Laboratories, University of the Ryukyus Hospital, Okinawa, Japan | [c] Department of Human Welfare, Okinawa International University, Okinawa, Japan | [d] Department of Geriatric Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, USA | [e] Department of Neurology and Layton Aging & Alzheimer’s Disease Center, Oregon Health & Science University, Portland, OR, USA | [f] Department of Neurology and Michigan Alzheimer’s Disease Center, University of Michigan, Ann Arbor, MI, USA

Correspondence: [*] Correspondence to: Junko Nishihira, MD, Department of Cardiovascular Medicine, Nephrology and Neurology, University of the Ryukyus School of Medicine, 207 Uehara, Nishihara-cho, Okinawa 903-0215, Japan. Tel.: +81 98 895 1150; Fax: +81 98 895 1416; E-mail: jonko100jp@yahoo.co.jp.

Correspondence: [*] Correspondence to: Hiroko H. Dodge, PhD, NIA-Layton Aging and Alzheimer’s Disease Center, Department of Neurology, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, CR131, Portland, OR 97239-3038, USA. Tel.: +1 503 494 6695; Fax: +1 503 494 7499; E-mail: hdodge@med.umich.edu.

Abstract: Background:Epidemiological studies have found frequent consumption of fatty fish is protective against cognitive decline. However, the association between circulating omega-3 polyunsaturated fatty acid (PUFA) levels and cognitive functions among the oldest old is not well known. Objective:To examine the association between serum PUFA levels and cognitive function among community-dwelling, non-demented elderly aged over 80 years old. Methods:The data came from the Keys to Optimal Cognitive Aging (KOCOA) study; an ongoing cohort of relatively healthy volunteers aged over 80 years old, living in Okinawa, Japan. One hundred eighty five participants (mean age 84.1±3.4 years) assessed in 2011 who were free from frank dementia (defined as Clinical Dementia Rating <1.0) were used for the current cross-sectional study. We examined whether serum omega-3 PUFAs (docosahexaenoic acid [DHA] and eicosapentaenoic acid [EPA]), arachidonic acid (AA), EPA/AA ratio, DHA/AA ratio, and DHA+EPA are associated with (1) age and (2) global cognitive function (Japanese MMSE) and executive function (Verbal Fluency Letter). Data was analyzed univariately by t-test and multivariately by cumulative logistic regression models controlling for age, gender, years of education, obesity, hypertension, diabetes, and dyslipidemia. Results:Serum DHA levels decreased with increasing age (p = 0.04). Higher global cognitive function was associated with higher levels of serum EPA (p = 0.03) and DHA + EPA (p = 0.03) after controlling for confounders. Conclusions:Higher serum EPA and DHA + EPA levels were independently associated with better scores on global cognitive function among the oldest old, free from dementia. Longitudinal follow-up studies are warranted.

Keywords: Cognitive function, DHA, EPA, KOCOA, Okinawa, oldest old, non-demented subjects, PUFA

DOI: 10.3233/JAD-150910

Journal: Journal of Alzheimer's Disease, vol. 51, no. 3, pp. 857-866, 2016