Herbs such as Bacopa (Bacopa monnieri) and Ashwagandha (Withania somnifera) are considered premier brain tonics (medha rasayanas) in Ayurveda. These herbs are specifically beneficial to brain tissue. They prevent brain aging and help in regenerating neural tissues. They also have an adaptogenic, stress-relieving and memory enhancing effect. In addition to ayurvedic evidence based on experience, several clinical trials and scientific studies have shown the efficacy and promising results of such herbs and ayurvedic formulations using these herbs.
In a 1993 study involving 286 adults with mild, moderate and severe mental retardation, it was found that those subjects with mild to moderate retardation showed significant improvement in concentration, memory and cognitive abilities after being given bacopa daily for 1 year. Similarly in a study conducted in 1999 it was found that children with mild to moderate mental retardation also showed substantial mental improvement after being treated with Mentat for 6 months.