By Peter Rebhahn, published on March 1, 2001 - last reviewed on December 15, 2010
New research suggests that the artificial sweetener aspartame may actually go to your head.
Anecdotal evidence that aspartame disrupts memory has been growing since the sugar substitute was approved in the early 1980s, though attempts to prove the claim have so far been equivocal. Previous studies have tested memory by asking aspartame users to remember lists of words or numbers -- tests of short-term memory. But according to Timothy M. Barth, Ph.D., a psychology professor at Texas Christian University, those studies focused on the wrong type of memory.
In his study of 90 students, Barth found that participants who regularly drank diet sodas containing aspartame performed as well as nonusers on laboratory tests. However, aspartame users were more likely to report long-term memory lapses like forgetting details of personal routines or whether or not a task had been completed.
"These people aren't crazy," says Barth. Instead, "the type of memory problems they report are not the type of memories that have been assessed in the typical laboratory study."
After reporting his findings at a recent Society for Neuroscience meeting, Barth cautioned that he thinks it's premature to condemn aspartame. But he does worry about the largely untested effects of long-term use. Already, he has made some converts. "Several of my graduate students who drank diet soda no longer do."