Until recently, advanced age and genes were the only well established risk factors for Alzheimer's disease; hence it has not been possible to develop preventive strategies. Now, evidence of modifiable risk factors for Alzheimer's disease is increasing. On p 1119, Purandare and colleagues report an association between spontaneous cerebral emboli and dementia.1 This case-control study provides evidence for the longlasting debate on the causes of Alzheimer's disease versus those of vascular dementia.

Purandare and colleagues used transcranial Doppler to detect spontaneous cerebral emboli, monitoring patients with Alzheimer's disease, patients with vascular dementia, and age and sex matched controls for an hour. These emboli were detected significantly more frequently in patients with dementia, and the frequency was similar in Alzheimer's disease and vascular dementia. This study thus joins a series …