Final answer:
The common factor among those over 50 linked to both atrial fibrillation and an increased risk of ischemic stroke is diabetes. Diabetes, in conjunction with other factors such as high blood pressure and hyperlipidemia, contributes significantly to the development of stroke.
Step-by-step explanation:
The factor common among individuals over 50 that is linked to both atrial fibrillation and an increased risk of ischemic stroke is diabetes. Diabetes is a well-documented risk factor for stroke due to its association with atherosclerosis in the arteries of the brain, which can lead to a blockage of the blood supply. In addition to diabetes, other major risk factors for stroke include high blood pressure, hyperlipidemia, smoking, obesity, and lack of physical activity, amongst others. To reduce the risk of stroke, it's crucial to maintain low blood pressure through lifestyle changes or medication, and manage diabetes effectively.