DMAE can increase mental cognition by boosting the levels of the chemical messenger's choline and acetylcholine. These two neurotransmitters boost cognitive function and enhance memory. Additionally, it can improve focus and attention by improving nighttime sleep and as a mild "brain" stimulant.
Further, acetylcholine helps conduct nerve impulses in the brain and choline is converted in the brain to another form of choline called phosphatidylcholine, which protects and rebuilds cell membranes within the brain. These benefits would theoretically improve memory loss due to the various increases in blood flow to the brain.

Function:
The benefits of DMAE bitartrate are being researched for the treatment of Alzheimer's disease and other age-related brain disorders. The results are still inconclusive, but for ADHD, the results are more promising. For example, there are many studies that showed ADD children that supplemented with DMAE bitartrate versus a placebo, scored a lot higher on cognitive tests.
Dosage
If you do decide to supplement with DMAE, the recommended dosages are between 400 and 1,800 mg daily. Personally, I would use this nutrient with other vitamins/herbs to help create a synergistic effect. Combining DMAE bitartrate with choline, ginseng, and ginkgo are excellent combinations, but it can be tiresome and redundant to buy these ingredients separately and take 10 pills per day.