What New in Psychology?
Eating mushrooms may reduce the risk of cognitive decline
By Jim Windell
Okay, we know that fruits and vegetables are good for you. And there is research that suggests that eating grapes and blueberries are important antioxidants and good sources of Vitamin C. Additionally, a regular fish diet, chocolate consumption and a handful of nuts daily may stave off the ravages of age-related cognitive decline.
But researchers at the National University of Singapore, publishing online in the Journal of Alzheimer's Disease, think another food may help as well.
A six-year study conducted from 2011 to 2017, collected data from more than 600 Chinese seniors over the age of 60 living in Singapore. The research was carried out with support from the Life Sciences Institute and the Mind Science Centre at NUS, as well as the Singapore Ministry of Health's National Medical Research Council.
A team of researchers from the Department of Psychological Medicine and Department of Biochemistry at the Yong Loo Lin School of Medicine at the National University of Singapore (NUS) found that participants who consumed more than two standard portions of mushrooms weekly had as much as 50 per cent reduced odds of having mild cognitive impairment (MCI). In the study, a portion was defined as three quarters of a cup of cooked mushrooms with an average weight of around 150 grams. Two portions would be equivalent to approximately half a plate. While the portion sizes act as a guideline, it was shown that even one small portion of mushrooms a week may still be beneficial to reduce chances of MCI.
MCI is typically viewed as the stage between the cognitive decline of normal ageing and the more serious decline of dementia. Seniors afflicted with MCI often display some form of memory loss or forgetfulness and may also show deficit on other cognitive functions, such as language, attention and visuospatial abilities. However, changes related to MCI can be subtle, as many people experiencing MCI do not experience disabling cognitive deficits that affect everyday life activities, which is characteristic of Alzheimer's and other forms of dementia.
According to Assistant Professor Lei Feng, who is from the NUS Department of Psychological Medicine and the lead author of this work, "People with MCI are still able to carry out their normal daily activities. So, what we had to determine in this study is whether these seniors had poorer performance on standard neuropsychological tests than other people of the same age and education background." The neuropsychological tests used in the study helped to measure various aspects of the participant’s cognitive abilities. Some of the tests were adopted from the Wechsler Adult Intelligence Scale.
In addition to the neuropsychological tests, the researchers conducted extensive interviews with the senior citizens to help determine an accurate diagnosis. "The interview takes into account demographic information, medical history, psychological factors, and dietary habits,” said Assistant Professor Feng. Also, a nurse measured blood pressure, weight, height, handgrip, and walking speed. After a two-hour standard neuropsychological assessment was performed, along with a dementia rating, the overall results of these tests were discussed in depth with psychiatrists involved in the study to get a diagnostic consensus.
The results were somewhat surprising to the research team. "This correlation is surprising and encouraging,” said Feng. “It seems that a commonly available single ingredient could have a dramatic effect on cognitive decline."
The mushrooms noted in the study were six commonly consumed mushrooms in Singapore, and included golden, oyster, shiitake and white button mushrooms, as well as dried and canned mushrooms. The researchers, however, believe that other mushrooms may also have beneficial effects. They also think the reason for the reduced prevalence of MCI in mushroom eaters may be due to a specific compound found in almost all varieties. That compound is called ergothioneine (ET).
"ET is a unique antioxidant and anti-inflammatory which humans are unable to synthesize on their own. But it can be obtained from dietary sources, one of the main ones being mushrooms," noted Dr Irwin Cheah, Senior Research Fellow at the NUS Department of Biochemistry.
But other compounds found in mushrooms may also be advantageous for decreasing the risk of cognitive decline. Certain hericenones, erinacines, scabronines and dictyophorines may promote the synthesis of nerve growth factors. Bioactive compounds in mushrooms may also protect the brain from neurodegeneration by inhibiting production of beta amyloid and phosphorylated tau, and acetylcholinesterase.
While the researchers plan to do further research with ET and other plant-based ingredients, for the time being, it appears that mushrooms may help reduce the risk of cognitive decline.
Which means, of course, when you order your next pizza, make sure you ask for extra mushrooms.
