Help for Dementia?

My mother has moderate dementia. I have taken her to a neurologist, who has prescribed Namenda. This drug seems to cause her to have a distant look, and she's losing her balance. So I have decided this may not be the best medication for her. She has been taking Aricept for almost 2 years now, and it's doing pretty good, but the neurologist said the two together worked great. Her primary physician seems to disagree from his observation he said the Namenda works good for about 3 months then it's downhill.
I also have been giving her Lydia Pinkham (a liquid with various herbs in it), which is more for energy, but it has Vitamin E and Vitamin C. I also give her ginkgo for her memory and the liquid Vitamin B12.
Are there any other herbs I can give her to help prolong her memory or assist in improving her mind as well as her health i.e., balance, strength?
On January 12, 2005, my mother had a mild stroke. The stroke was on the right side, but affected the left side. She can walk, she can't use her left had has very little strength. She can raise her left arm up, but lately she's becoming more bent over and it's getting harder for her to walk. Prior to the stroke she had the energy of a 65 year old and she has the spirit of a 30 year old. My mother is 85 years old, born 11-16-1919.
I'm an only child and she's all I have so whatever you can advise to help will be appreciated immensely. I do know that once we are born we must die, but I would like to provide her with the best possible care and health until that time comes.

Diet, digestion and general circulation are often insufficient in old age. With these insufficiencies, there is often a build up of toxins in the body. Nutrition is of prime importance. The diet should include a little meat or fish, along with vegetable soups or broths, which can include circulatory stimulants like ginger and cinnamon to support general circulation and digestion. Refined and processed food, fatty foods and fried foods should be avoided.
Supporting the nervous system and the blood circulation may help to improve balance. Oats, in oatmeal porridge and oatstraw tea, and vitamin B complex, are nerve nourishing. Deficiency of folic acid (which is included in a vitamin B complex supplement) is connected to heart disease and dementia
Rosemary, sage, oregano and thyme are antioxidants that help to get rid of toxins from the body. These can be included in meals or in teas. Rosemary is also used to strengthen the heart and improve circulation to the brain. German chamomile is anti-inflammatory and provides digestive support. Inflammation around the heart and the brain are thought to be implicated in heart and brain insufficiency. Additional support to the liver helps to metabolize and excrete toxins. A natural way to include liver support in the diet is to add dandelion root to soup stocks.
Essential oils of lemon balm and lavender can be helpful in improving mood and restlessness in dementia. These can be used by adding a few drops to the bathwater or to a spray container filled with pure water.