Nontraditional Risk Factors for Ischemic Stroke

Search Strategy and Selection CriteriaIn this review, we defined traditional risk factors as those used in the Framingham study (ie, age, sex, hypertension, diabetes mellitus, cigarette smoking, cardiovascular disease [CVD], atrial fibrillation, and left ventricular hypertrophy) 15 and hypercholesterolemia. Others are defined as nontraditional risk factors if the association between the factors and the occurrence of stroke was demonstrated with plausible biological explanation.We identified references for this review by searching PubMed and ClinicalTrials.govpublished in English up to January 2015, with the search terms stroke, cerebral infarction, cerebrovascular, risk factor, and trigger.Additionally, we searched references from relevant articles and reviews.The final reference list was generated on the basis of originality and relevance to this topic.Because of space limitation, we were not able to discuss many nontraditional risk factors in depth with critical analysis.We did not include serological biomarkers such as homocysteine.Genetic studies are mentioned only briefly at the end because they are not modifiable risk factors. Nontraditional Risk FactorsIdentification of nontraditional risk factors for stroke is increasing.These conditions include obesity and metabolic syndrome, sleep apnea, chronic inflammation, chronic kidney disease (CKD), and nutrition/diet.In addition, exposure to certain conditions including psychosocial stress, environmental factors, infection, and alcohol abuse may exert a single, sharp, and transient effect on the pathophysiological process, precipitating the onset of stroke/TIA.However, it is often difficult to distinguish an emerging risk factor from a novel triggering factor, but nature (eg, abruptness) of exposure to the condition in temporal relation to occurrence of the stroke event and the severity of the condition may help in making this distinction.