Blood pressure rises with aging and the risk of becoming hypertensive in later life is considerable. Several environmental factors influence blood pressure. High salt intake raises the blood pressure in salt sensitive individuals; lack of exercise, obesity, and depression can play a role in individual cases. The possible roles of other factors such as caffeine consumption, and vitamin D deficiency are less clear. Insulin resistance, which is common in obesity and is a component of syndrome X (or the metabolic syndrome), is also thought to contribute to hypertension. One review suggests that sugar may play an important role in hypertension and salt is just an innocent bystander.
Emerging data suggest an important correlation between metabolic syndrome and risk of stroke.  Each of the components of metabolic syndrome has been associated with elevated stroke risk, and evidence demonstrates a relationship between the collective metabolic syndrome and risk of ischemic stroke.  Metabolic syndrome may also be linked to neuropathy beyond hyperglycemic mechanisms through inflammatory mediators.