AS187 - Serum fatty acids and incidence of ischemic stroke in women

Investigator Names and Contact Information

Ka Kahe (kk3399@cumc.columbia.edu)

Introduction/Intent

While coronary heart disease (CHD) and ischemic stroke share some major risk factors, limited epidemiological data on dietary fats and vascular disease risk indicate that fatty acids have different associations with ischemic stroke than with CHD. The established associations between types of fat and CHD do not appear to apply to ischemic stroke. Particularly, high stroke rates and low CHD rates have been observed in people with low animal fat intake. One explanatory hypothesis for these “paradoxical” observations is that arteriosclerosis in different types of cerebral arteries has different causal patterns. Fatty acids or blood lipids may not be as important as other factors such as blood pressure in the pathogenesis of a certain type of ischemic stroke. However, confirmatory data on the associations of fatty acids and subtypes of ischemic stroke, including lacunar (small artery), atherosclerotic (large artery), and cardioembolic infarction, are lacking.

Measurement of the composition of serum fatty acids has shown promise as an objective marker of dietary fat intake and has been proposed as a useful tool in ranking fatty acid intake in epidemiological studies. This study will examine the associations between serum fatty acids and risk of ischemic stroke and its subtypes among postmenopausal women. A prospective nested case-control study of 971 ischemic stroke cases and 971 matched controls in the Women’s Health Initiative (WHI) Observational Study is proposed to achieve the objectives. This project is a supplement to a NINDS-funded stroke study in the WHI Observational Study (5R01NS042618; PI: Dr. Sylvia Wassertheil-Smoller). We will use cases and controls that have already been identified and classified, and incorporate the high-quality existing WHI database on clinical, biological, and lifestyle variables. The proposed study will help clarify possible differences of these nutrients in relation to ischemic stroke and to CHD. The data generated from this study should provide new information on the etiology of ischemic stroke and data for new explorations of dietary causes.

Primary Aims: To examine the pattern of serum fatty acids as potential biomarkers in relation to risk of ischemic stroke and its subtypes (lacunar, atherosclerotic, and cardioembolic infarction) in postmenopausal women. Specifically, we will test the following hypotheses:

· Higher levels of serum saturated fatty acids - myristic (14:0) acid and palmitic (16:0) acid, and trans fatty acids - elaidic acid (18:1, trans) and linelaidic acid (18:2, trans) are associated with increased risk of atherosclerotic infarction but not with other types of ischemic stroke.

· Higher levels of serum omega-3 fatty acids - α-linolenic acid (18:3), eicosapentaenoic acid (20:5) and docasahexaenoic acid (22:6), and omega-6 fatty acids - linoleic acid (18:2) and arachidonic acid (20:4) are related to decreased risk of atherosclerotic infarction but not to other types of ischemic stroke.

Secondary Aims

· To explore possible associations between serum fatty acid concentrations and blood pressure and serum lipoprotein profile.

· To assess the correlations between serum fatty acids and self-reported dietary fat intake, and to explore the associations between dietary fat intake and subtype of ischemic stroke.

Results/Findings

Some of the publications related to this ancillary study are:

Ms944 - Yaemsiri S, Sen S, Tinker L, Rosamond W, Wassertheil-Smoller S, He K. Trans fat, aspirin, and ischemic stroke in postmenopausal women. Ann Neurol. 2012 March 1 [Epub ahead of print]

For a complete, up-to-date list of WHI papers related to this ancillary study, please use the searchable Bibliography section of this website. To search for papers by study number, access the Simple Search, and enter the study number in the “Related Studies” field.

Note: AS187 used the same cases and controls as AS126 [see AS126 Participant Selection Summary]