Exploring Dietary Supplements as a Defense Against Cognitive Decline in Alzheimers Disease

Protein Fragment from Soybeans Protects Against Cognitive Decline in Alzheimer’s Model

Research Overview

A study conducted by scientists at Kyushu University, Japan, has discovered that a small protein fragment, or dipeptide, consisting of only two amino acids, can guard against cognitive decline linked to Alzheimer’s disease. The findings were published in the journal npj Science of Food.

Understanding Alzheimer’s Disease

Forgetfulness is often dismissed as a natural part of aging; however, it may be one of the earliest indicators of Alzheimer’s disease. This progressive condition is characterized by a gradual loss of memory and cognitive abilities, commonly referred to as dementia. Alzheimer’s disease ranks among the leading causes of death in the United States, with approximately 30 million individuals worldwide suffering from dementia related to the disease.

Despite age being a significant risk factor, Alzheimer’s is not solely a condition of the elderly, nor is it a typical aspect of aging. Currently, there is no definitive cure; however, treatments exist that can manage symptoms and slow disease progression. These treatments primarily focus on reducing the breakdown of neurotransmitters, particularly acetylcholine, which is essential for learning and memory. Another class of medications aims to inhibit excessive glutamate activity, a neuro-signaling molecule elevated in the brains of Alzheimer’s patients, in order to enhance memory, attention, and cognitive functions.

Study Methodology

Researchers at Kyushu University previously established that dipeptides containing the amino acid proline can enter the brain and distribute in various areas, including the hippocampus and cerebral cortex. They sought to determine whether these dipeptides could alleviate cognitive and memory impairments associated with Alzheimer’s disease.

In the study, mice injected with an amyloid protein fragment—associated with Alzheimer’s—served as the model to assess the protective effects of the dipeptides. The mice were administered the dipeptide Tyr-Pro (Tyrosine-Proline) for a duration of 16 days, followed by cognitive and memory assessments.

Study Results

The results indicated that mice receiving the Tyr-Pro dipeptide exhibited improved performance on tests measuring working and long-term memory compared to those not given the dipeptide. However, both groups of impaired mice performed below the level of normal mice without induced Alzheimer’s symptoms. This suggests that dipeptides may slow cognitive decline but do not completely eliminate symptoms.

Mechanism of Action

The researchers delved into the neuroprotective mechanisms of the dipeptides, concluding that they enhance the production of acetylcholine, particularly in the cerebral cortex, which is linked to both short- and long-term memory functions.

Implications and Future Research

This study marks a significant advancement, demonstrating for the first time that dipeptides can travel from the stomach to the brain intact and may protect against cognitive decline related to Alzheimer’s disease. However, further research is needed to determine if these effects are replicable in humans, as the study did not investigate other dipeptides or the impact of long-term consumption of Tyr-Pro.

The findings highlight the potential of dietary supplements, such as the Tyr-Pro dipeptide, in combating memory decline associated with Alzheimer’s. Dr. Toshiro Matsui, the lead researcher, stated, “On top of the possibility of being broken down during digestion, peptides then face the challenge of crossing a highly selective barrier to get from the blood into the brain. While our previous studies were the first to identify a dipeptide able to make the journey, our new studies show that it can actually affect memory in mice. We hope that this is a step forward toward functional foods that could help prevent memory degradation or even improve our memories.”

References

Original study: Tanaka, M., Kiyohara, H., Yoshino, A. et al. Brain-transportable soy dipeptide, Tyr-Pro, attenuates amyloid β peptide25-35-induced memory impairment in mice. npj Sci Food 4, 7 (2020).

Press release: https://www.eurekalert.org/pub_releases/2020-06/ku-mii061820.php

Prevalence of Alzheimer’s disease: https://www.who.int/news-room/fact-sheets/detail/dementia

Classes of medications for Alzheimer’s disease: https://www.alz.org/alzheimers-dementia/treatments/medications-for-memory

Image by Jing from Pixabay.