Your question got me to reading the lithium articles which jogged my
memory on something called GSK-3 which is involved in the formation of
AD plaques.  

"...an active ingredient of Danggui Longhui Wan, a traditional Chinese
medicine recipe used in the treatment of chronic diseases such as
leukemias" was shown to inhibit GSK-3.

The authors suggest that these compounds are a place to start looking
for new drugs in the treatment of AD.  

Lithium inhibits GSK-3 but has a range of other effects as well.  The
Chinese herbal remedy is selective but only tested in the test tube;
nothing can be said for long-term treatment or usefulness.  I wouldn't
even know where to start looking for "Danggui Longhui Wan" ;-) nor
would this be prudent with so little research.  

There has never been a more exciting time in research into dementia.
Unfortunately, most of us will suffer the loss of a loved one to the
disease before this new research turns into something useful.  

Until that time, I'll take my vitamins C and E, 1/2 an aspirin a day,
eat blueberries and a colourful diet and cross my fingers  :-)

Darryl.