Page 175 - The Memory Program How to Prevent Memory Loss and Enhance Memory Power

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While it remains unclear which of these many actions underlies acetyl-l-carnitine's promemory
effects, I have chosen to discuss it under the cholinesterase inhibitor class of compounds.

Promising results emerged in small numbers of patients with Alzheimer's disease, but larger
placebo-controlled trials met with failure. Other small-scale studies have shown an advantage for
acetyl-l-carnitine over placebo in people with mild memory loss, but there are also several negative
reports. Like other compounds in its class, there are no long-term studies to determine if it can
prevent age-related memory loss.

The usual dose is 2 to 5 grams daily, and there are few side effects. You can obtain acetyl-l-
carnitine in health food stores, and this is an example of how the same substance can surface as both
a modern pharmaceutical compound and an alternative medication. In fact, as more and more
research is conducted with various types of alternative medicines, the two fields will begin to
converge and their boundaries may eventually disappear altogether.

The Rise and Fall of Tacrine (Cognex)

As the largely negative clinical trials with choline, lecithin, and acetyl-l-carnitine demonstrate,
promemory effects in rats or mice are not easy to replicate in people. Improving cognition in the
primitive rodent brain is a lot simpler than boosting it in the ultracomplex human brain.

As a matter of fact, by the mid 1980s, research with a variety of cholinergic compounds— lecithin,
choline, phosphatidylcholine, acetyl-l-carnitine, and physostigmine— had run into a dead end, despite
the investment of over a billion dollars by a number of drug companies in the United States, Europe,
and Japan. Then came a report by William Koopmans Summers describing strong efficacy for a
cholinesterase inhibitor named tetrahydroaminoacridine or tacrine (THA, Cognex) in seventeen
patients with Alzheimer's disease. A tortuous road ensued for tacrine, with many ups and downs and
the U.S. Congress getting involved in supporting research and development of this Warner Lambert
drug. Eventually, the FDA approved it as a treatment for Alzheimer's disease, because high doses of
the medication showed a significant, though small, advantage over placebo in cognitive performance.

But after tacrine was approved by the FDA, it fell by the wayside because of its liver toxicity. This
risk was so high that after tacrine was