These "cholinesterase inhibitors" include tacrine (Cognex), donepezil (Aricept), rivastigmine (Exelon) and galantamine (Razadyne, formerly called Reminyl).

CNN: Better understanding of dementia leading to more effective therapies

Cholinesterase inhibitors are not useful in dementia caused by Huntington's disease or traumatic brain injury.

CNN: Better understanding of dementia leading to more effective therapies

Donepezil is one of a class of drugs known as cholinesterase inhibitors while memantine is a glutamate moderator.

CNN: Hard to tell, but drug helps as Alzheimer's progresses

It's unclear if the results would apply to other cholinesterase inhibitors such as galantamine (Razadyne) or rivastigmine (Exelon), the editorial noted.

CNN: Hard to tell, but drug helps as Alzheimer's progresses

"I think the cholinesterase inhibitors have established themselves as the standard of care, " says Roger Lane , clinical program leader for Novartis' entrant, Exelon.

FORBES

Memantine has fewer side effects than the cholinesterase inhibitors.

CNN: Better understanding of dementia leading to more effective therapies

While cholinesterase inhibitors are useful in many early dementias, studies have not shown that treatment of patients with mild cognitive impairment, which is the condition before dementia, prevents or slows progression to dementia.

CNN: Better understanding of dementia leading to more effective therapies

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