Three drugs that treat people with moderate-to-severe Alzheimer's disease have been approved for use on those with milder symptoms.
A fourth medication only used on people with late-stage Alzheimer's disease can now be given to patients with less severe symptoms.
NICE's decision is a reversal of guidance it published in 2007 which blocked more widespread use of the drugs.
Each medication slows progression of the disease and costs around £2.80 a day for each patient.
The Institute's change of mind comes on the back of new research which shows that Aricept, Exelon, Reminyl and Ebixa are more effective than first thought in treating people going through the milder stages of Alzheimer's.
Ebixa is used for severe symptoms generally seen late on in the development of the disease. It has now been recommended for use on NHS patients at the moderate-to-late stages.
The other three drugs are for people with early to moderate symptoms.