Tea and mushrooms: Two promising targets for tackling cognitive decline ‘amid failure of big pharma’

At the second Healthy Ageing APAC Summit 2019 held in Singapore, Dr Feng Lei from the National University of Singapore, discussed the current drug development dilemma and the potential role of phytonutrients in preventing dementia.

“Dementia occurs when cognitive function (memory, thinking) declines and reaches a threshold that limits a person’s ability to perform normal daily functions,”​ said Feng, Principal Investigator from the Department of Psychological Medicine at the National University of Singapore.

Dilemma of dementia​

Pharma companies have invested billions of dollars in research, but clinical trials in cognitive-related diseases have seen more failures than successes, he said.

“Most Alzheimer’s disease trials do not make the cut in Phase 3. The failure rate is 99.6% in the past 12 years​,” said Feng.

It is generally believed that the risk of dementia can be reduced by modifying risk factors, such as diet.

Time for tea ​

In a study​ conducted by Feng et al​. on 716 adults aged 55 years or older, total tea consumption was associated with better cognition performances on memory, executive function, and information processing speed.

This effect might be due to the presence of phytochemicals such as L-theanine and epigallocatechin gallate (EGCG) in tea, which are known for their antioxidants and anti-inflammatory benefits.

In fact, they found the protective effect of tea consumption on cognitive function was not limited to any particular type of tea, in this case, was black, oolong and green tea.

Make way for mushroom​

In another study​ by Feng et al​. they studied 600 adults above the age of 60 with mild cognitive impairment (MCI) and mushroom intake.

MCI is typically viewed as the stage between the cognitive decline of normal ageing and the more serious decline of dementia.

Seniors who consumed more than two portions of mushroom per week were found to have slower cognitive decline.

They attributed this finding to the presence of ergothioneine in mushroom, a known antioxidant and anti-inflammatory compound. It protects the body from oxidative stress and disease.

People with MCI were found to have significantly lower levels of ergothioneine in their blood compared with healthy individuals of the same age.

They reported that ergothioneine can protect against beta-amyloid; a protein implicated in dementia. Mouse studies also showed ergothioneine can protect the brain and prevent memory deficits in neurodegenerative models.

As these studies were conducted on Asian cohorts, Feng recommended more clinical studies as well as evaluating with biomarkers and brain scans, on top of the cognitive assessments.

What is next​

Feng mentioned medium-chain triglycerides (MCTs) might possibly benefit certain people with Alzheimer’s disease.

An example is Axona, a commercial medical food that increases total brain energy metabolism by increasing ketone supply.

“However, more studies are still needed to determine the safety and effectiveness of MCTs in preventing dementia​.”

Feng said there is a currently a lot of research in curcumin, a chemical found in turmeric, also a potential treatment for Alzheimer's disease.

Curcumin is shown to have antioxidant, anti-inflammatory and anti-amyloid properties. A commercial example is Theracurmin, a bioavailable form of curcumin.

“We need more longitudinal studies and clinical trials that evaluate people already with MCI. Hopefully one day, we can find the nutritional solution for the promotion of healthy longevity​.”