Memantine is also especially useful in the treatment of patients with Alzheimer's disease and patients with vascular dementia.

CNN: Better understanding of dementia leading to more effective therapies

Between 1 and 4 percent of people over the age of 65 have vascular dementia, according to the Mayo Clinic.

CNN: Mediterranean diet may help prevent dementia, study says

Known as brain infarcts, they're involved in vascular dementia, the second most common form of dementia, after Alzheimer's disease.

CNN: Mediterranean diet may help prevent dementia, study says

Novartis is conducting a 700-patient trial of Exelon in vascular dementia.

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In general, cholinesterase inhibitors have shown some benefit for patients with vascular dementia, those with mixed Alzheimer's and vascular dementia, patients with the disease known as "dementia with Lewy bodies, " and dementia from Parkinson's disease.

CNN: Better understanding of dementia leading to more effective therapies

People who have both Alzheimer's and vascular disease -- a condition called mixed dementia -- have a more rapid progression of Alzheimer's disease, Cole said.

CNN: Mediterranean diet may help prevent dementia, study says

In a study published last year in the journal Cortex, Dr. Rankin and her colleagues studied the ability to detect sarcasm in 102 patients who had been diagnosed with four progressive diseases that lead to memory loss: frontotemporal dementia, Alzheimer's disease, progressive supranuclear palsy and vascular-cognitive impairment.

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