The rate of dementia-associated cognitive decline varies depending on the type of dementia a person has, new research suggests.

To gather their data, researchers at Hopital Salengro in Lille, France, followed 970 patients with three common types of dementia for roughly six years. A total of 663 patients had Alzheimer’s disease alone, 166 had Alzheimer’s coupled with cerebrovascular disease, and 141 had vascular dementia. Cognitive decline occurred more quickly among patients with only Alzheimer’s disease, followed by those with Alzheimer’s and cerebrovascular disease. Those with vascular dementia demonstrated the slowest rate of decline, according to the study. The average annual decline was significantly different among the three dementia types, report authors note.

Researchers used the Mini Mental State Examination (MMSE) to gauge cognitive function. They noticed that patients with Alzheimer’s and cerebrovascular disease tended to be older than other patients, and those with vascular dementia scored higher than others on the first round of tests. The full report appears in the February issue of the Journal of Neurology, Neurosurgery, and Psychiatry.