The cause and cure of Alzheimer's remain elusive

Nearly 100 years on, the brain cell-destroying disease first described by Alois Alzheimer in 1906 has no cure and its causes remain open to conjecture.

"At the moment we can't see the light at the end of the tunnel - we're not even sure we are in the right tunnel," says Dr Phil Wood of the North Shore Hospital memory clinic.

But scientific research has greatly advanced understanding of the processes involved.

The disease has been linked to abnormal accumulation of an amyloid protein, which is toxic to brain cells, but scientists are unclear about the process that causes cells not only to die but to not be replaced.

Although recent research centred on treatment with cholesterol-lowering drugs suggests diet may play a part, Wood says sufferers are more likely to be genetically predisposed.

"I know a number of vegans and vegetarians who have Alzheimer's and similar dementias. The evidence points towards an inherent metabolic biochemical process and there's a susceptibility within families."

Whether the lumpy amyloid deposits found in patients are the tombstones of the disease or the cause of cell destruction remains to be seen, says Wood. The development of therapies to reduce the accumulation of amyloids would enable more control of the disease but was unlikely to provide a cure.

"To find a way to stall the process of cell destruction is the holy grail of Alzheimer's research. It's a pretty big question we are asking."

Research has undoubtedly been hampered by attitudes towards Alzheimer's - "it's not a disease rated highly by society".

Despite the difficulties, scientists in research-averse New Zealand have made some important breakthroughs. Two years ago, Auckland University professor of anatomy Dr Richard Faull turned conventional wisdom about cell death on its head, finding that even in diseased brains, cells could repair themselves.

This week's announcement that a polyglutamine protein, TBP, is also present and may play a role, opens a new avenue for international research.

For now, inhibitor drugs such as Aricept and Exelon provide "modest but important benefits" by easing symptoms and slowing the disease's progression. "It's equivalent to turning the clock back nine to 12 months which, for a person in their 70s, can be quite worthwhile," says Wood.

"The lack of a subsidy is a big issue because only a minority can afford it."