http://news.yahoo.com/s/nm/20070430/hl_nm/alzheimers_memory_dc

(excerpt)

WASHINGTON (Reuters) - Mental stimulation and drug treatment may help
people with brain ailments such as Alzheimer's disease regain
seemingly lost memories, according to research published on Sunday.

Scientists used two methods to reverse memory loss in mice with a
condition like Alzheimer's -- placing them in sort of a rodent
Disneyland to stimulate their brains, and also using a type of drug
that encourages growth of brain nerve cells.

Neuroscientist Li-Huei Tsai of the Howard Hughes Medical Institute and
the Massachusetts Institute of Technology said such methods might
yield similar benefits in people with Alzheimer's disease or other
types of dementia that rob them of their memory and ability to learn.