In the future, a cup of tea may be just what the doctor orders to reduce the cognitive impairments associated with obesity.
An animal study conducted by Schizophrenia Research Institute-supported scientist, Dr Yinghua Yu, has found that teasaponin supplementation may be used to prevent neurodegeneration and improve cognitive deficits associated with obesity.
There is a high incidence of obesity and metabolic issues in mental disorders such as schizophrenia. The obesity can be caused by the disorder itself, or it could be a result of medication side effects or due to lifestyle factors. Dr Yu and Prof Xu-Fung Huang are searching for a way to improve cognitive function by dealing with the first two causes.
People classified as obese are often leptin-resistant, which means that their brain has reduced levels of leptin, the hormone that stops us from feeling hunger once we've eaten. Leptin also facilitates learning and memory functioning in the brain.
Brain-derived neurotrophic factor (BDNF) promotes the brain's ability to grow new neurones, which are also important for learning and memory. A high fat diet, which often results in obesity, reduces the amount of BDNF in the brain, however this can be reversed with the administration of leptin.
So, leptin is an important part of the brain's ability to maintain particular cognitive functions and is an integral part of body's way of maintaining a healthy weight, which made it an interesting therapeutic target to explore.
The recent study from Dr Yu found that teasaponin supplementation improved leptin signalling in the brain as well as the amount of BDNF growth caused by leptin. This may have beneficial effects in reducing cognitive decline associated with obesity.
It must be noted, however, that the dose of teasaponin obtained by frequently drinking tea is significantly lower than the doses in the study. Clinical trials are needed to determine the optimal dose in humans, as well as any risk of toxicity over long-term use.