Armitage was Chief Investigator for the ASCEND aspirin trial, which studied cardiovascular disease in 15,480 patients with diabetes.[9][10] ASCEND was the largest ever study that had every been performed to investigate whether aspirin should be used to prevent cardiovascular disease in diabetic patients.[10] The trial found that whilst aspirin reduces the risk of cardiovascular events by 12%, it increases the risk of major bleeding.[11] As an addition to the ASCEND study, Armitage was supported by Alzheimer's Research UK to study the impact of aspirin and fish oil on memory and cognition in patients with diabetes and Alzheimer's disease.[12] They also studied whether aspirin changes the risk of developing dementia and Alzheimer's disease.