[The Economist] When memory fails

DECODING DARKNESS: THE SEARCH FOR THE GENETIC CAUSES OF ALZHEIMER'S DISEASE. By Rudolph E. Tanzi and Ann B. Parson. Perseus Publishing; 281 pages; $26 and £15.95.

TOTAL MEMORY WORKOUT: 8 EASY STEPS TO MAXIMUM MEMORY FITNESS. By Cynthia R. Green. Bantam Doubleday Dell; 256 pages; $23.95. Piatkus Books; £14.99.

THE VINTAGE BOOK OF AMNESIA: AN ANTHOLOGY OF WRITING ON THE SUBJECT OF MEMORY LOSS. Edited by Jonathan Lethem. Vintage Books; 352 pages; $14

Can science cure memory loss? Can routines? Can laughter? Three new books highlight different approaches

"BEHOLD in the plains, and caves, and caverns of my memory...I run; I fly; I dive on this side and that, as far as I can, and there is no end." Why can some of us no longer do this? That was St Augustine in about 400AD, but everyone shares his basic physiological apparatus. As Rudolph Tanzi, a professor of neurology at Harvard University, says in "Decoding Darkness: The Search for the Genetic Causes of Alzheimer's Disease", the brain is "an electrical and chemical universe wherein the wizardry of thinking and remembering, consciously and unconsciously, depends on as many connecting neurons, or nerve cells, as there are stars in the Milky Way."

Reading about the brain is both flattering and depressing. Given what Mr Tanzi tells us of its "quadrillion connections supported by trillions of nerve fibres", its branching neurons, its "protoplasmic kisses" whereby a message "vaults across a sliver of space called a synaptic cleft and into the outstretched arm of another neuron", surely we should be a race of demi-gods. As it is, we have to buy books like Cynthia Green's "Total Memory Workout: 8 Easy Steps to Maximum Memory Fitness" in order to remember where we left the car keys.

Of course, people have always forgotten the car keys (or where they left the horse). Ms Green's book, as well as offering helpful memory aids (minutes, lists, files), also suggests methods for training the memory itself which sound uncannily like those described in "The Art of Memory" (1966), Frances Yates's classic history of ancient, medieval and Renaissance memory systems. Take step five, where Ms Green suggests associating the thing to be remembered with a clear visual image. It helps, she says, to make the picture unusual or exaggerated or silly&emdash;one of the rules, almost word for word, in a standard Latin treatise on rhetoric written in the century before Christ, which recommends memory-boosting images ornamented with crowns, or stained with mud or blood, or rendered comic in some way.

But no imagery can save you from amyloid plaques and neurofibrillary tangles. According to Mr Tanzi, plaques in particular are the "litter" and "rubble" that strew the neuronic galaxies of the brain. "Decoding Darkness" tells how he and others have been hunting for the genetic causes of this so-called "brain dirt", a fearsome subject which he conveys with maximum fitness and panache. Passages of autobiography and anecdote enliven the hard science, but the book's real drama is at a cellular level. This, on a scale of 60 trillionths of an inch wide, is where the chase is&emdash;up and down the corridors of chromosomes, in among the proteins, at the cutting edge of enzymes and at the spot where the cut goes wrong. So infectious is his enthusiasm that, like children at a pantomine, readers happily cheer or hiss at his peculiar sounding chemicals&emdash;especially his villain, A-beta: "a protease made a cut right through the middle of A-beta, look what it meant! A-beta gets broken in two&emdash;deactivated! trounced!"

A-beta is a section of protein which, if cut free in its entirety from its parent protein, ends up in plaques. In Mr Tanzi's opinion, it is in its A-beta 42 form (nothing is simple) the Hannibal Lecter of the brain&emdash;an image that might itself have come from a memory handbook. It is also far enough "upstream" in the development of Alzheimer's to be a sufficient target for a cure. By the end of the book drugs and even vaccines are being developed, and the signs are hopeful. They need to be. He estimates that there are 12m-14m Alzheimer's sufferers worldwide (more if you include the unrecognised and unreported cases), the numbers increasing with longevity. One of the best things about "Decoding Darkness" is that it never loses itself in the chemistry. Heading each chapter is a paragraph charting the terrible progress of the disease in a real family, and making the connection between the death of the cell and the death of the self.

The appealing idea that your you-ness is bound up with your memory runs up against the difficulty that memory is not reliable. As David Wilson puts it, what we commonly call memories include "confabulations, artificial constructions of our own design built round particles of retained experience, which we attempt to make live again by infusions of imagination." Mr Wilson's piece is one of the contributions to Jonathan Lethem's anthology, "The Vintage Book of Amnesia", where it stands almost as an invitation to the playful, circular, occasionally frightening stories that surround it.

The book of laughter and forgetting

Whether through a bang on the head, or a futuristic brainwashing experiment, or something inexplicable which opens a gap from one moment to the next, here are characters all asking "Who am I?" The question is either the start of a detective hunt, as in Cornell Woolrich's "The Black Curtain", or an existential enquiry, as in Robert Sheckley's "Warm". Sometimes the answer is to make yourself up, or more tricksily, that you've already been made up, like a Pirandello character. At other times, the conclusion is a semantic cul-de-sac. Russell Hoban's amnesiac gets stuck at "What?", to which the reply is: "This is what. And what is this. This is what what is." Then again, the blank wall can turn momentarily into a window. There is a sense almost of literary envy in Martin Amis's account of Mary's perceptual innocence in "Other People" or in the way Dennis Potter in "Ticket to Ride" describes his character watching people eating: "Look at the prongs on the fork! What strange objects. What funny things to do."

But as Oliver Sacks's books repeatedly demonstrate, fiction has to run hard to keep up with real funny things. Mr Lethem reprints his piece "The Last Hippie", an extraordinary and moving study of the interactions between memory, identity and music in a brain-damaged man for whom the present is the late 1960s. Though quite unable to absorb anything more recent, Greg F can nevertheless retain the post-1960s music of his favourite band, The Grateful Dead&emdash;"the music of the future", as he describes it with serious appreciation. Responsive in conversation, guileless, humorous and charming, he could pass for an idiot savant. As Greg's father bravely put it: "Frontal lobes&emdash;who needs 'em?"