Scientists in Belgium conducted a study1 where Dimethylaminoethanol (DMAE) was applied as a 3% gel to areas of loose skin. They concluded that DMAE increased skin tone and firmness. The exact mechanism of DMAE skin toning and firming is unclear. Speculation into DMAE's skin firming centers on stabilizing membranes, acetylcholine boosting, and/or reducing lipofuscin deposits. Regardless, DMAE's skin firming is often immediate and noticeable, as was found in the Belgian study. Further, some report a cumulative DMAE firming effect when used over time.
Dr. Perricone, in his book " The Wrinkle Cure," also promotes DMAE as preventing cell deterioration - though these claims have only been substantiated by his own limited study.
1Skin Research and Technology (August 2002, page 164)