Improving Effects of Hop-Derived Bitter Acids in Beer on Cognitive Functions: A New Strategy for Vagus Nerve Stimulation

Abstract

Dementia and cognitive decline are global public health problems. Moderate consumption of alcoholic beverages reduces the risk of dementia and cognitive decline. For instance, resveratrol, a polyphenolic compound found in red wine, has been well studied and reported to prevent dementia and cognitive decline. However, the effects of specific beer constituents on cognitive function have not been investigated in as much detail. In the present review, we discuss the latest reports on the effects and underlying mechanisms of hop-derived bitter acids found in beer. Iso-α-acids (IAAs), the main bitter components of beer, enhance hippocampus-dependent memory and prefrontal cortex-associated cognitive function via dopamine neurotransmission activation. Matured hop bitter acids (MHBAs), oxidized components with β-carbonyl moieties derived from aged hops, also enhance memory functions via norepinephrine neurotransmission-mediated mechanisms. Furthermore, the effects of both IAAs and MHBAs are attenuated by vagotomy, suggesting that these bitter acids enhance cognitive function via vagus nerve stimulation. Moreover, supplementation with IAAs attenuates neuroinflammation and cognitive impairments in various rodent models of neurodegeneration including Alzheimer’s disease. Daily supplementation with hop-derived bitter acids (e.g., 35 mg/day of MHBAs) may be a safe and effective strategy to stimulate the vagus nerve and thus enhance cognitive function.

Identification of Human Brain Proteins for Bitter-Sweet Taste Perception: A Joint Proteome-Wide and Transcriptome-Wide Association Study

“…Some research has shown that bitter beverage consumption was related to brain function. For example, several epidemiological studies have indicated that moderate consumption of alcoholic beverages, such as wine and beer, may benefit cognitive function [ 8 ] and lower the risk of dementia [ 9 ]. The bitter component of beer, iso-alpha-acids, could improve hippocampus-dependent memory through vagus nerve activation [ 8 ].…”

“…Epidemiological studies have shown that moderate consumption of alcohol, such as wine and beer, was beneficial to cognitive function [ 8 ]. The main bitter components of beer, iso-alpha-acids (IAAs), enhance hippocampus-dependent memory and prefrontal cortex-associated cognitive function [ 9 ]. However, most current studies have been done by tracking the metabolism of beverage ingredients in the brain, however, there is limited research on the relationships between taste perception and human brain proteins.…”

Reaction Time and Visual Memory in Connection with Alcohol Use in Schizophrenia and Schizoaffective Disorder

“…Some animal model studies found negative association between alcohol and cognition mediated by reductions in cell density in the cerebral cortex [ 102 ] and alterations of cholinergic interneurons in the Nucleus Accumbens [ 103 ]. Other animal model studies suggested positive association between alcohol and cognition thought to be mediated by enhancement of brain metabolite clearance [ 104 ] and activation of the vagus nerve [ 105 ], antioxidant system [ 106 , 107 , 108 , 109 ], and other biological processes [ 110 , 111 , 112 ]. However, none of these findings have thus far been confirmed to be causally important.…”

Reaction Time and Visual Memory in Connection to Alcohol Use In Schizophrenia and Schizoaffective Disorder

“…Animal-model studies suggested alcohol to be associated with cognition negatively through decreasing cell density in the cerebral cortex [108], altering accumbal cholinergic interneurons [109] and positively through enhancing brain metabolite clearance [110], activating vagus nerve [111], anti-oxidant system [112,113,114,115] and other biological processes [116,117,118]. However, none of these findings have so far been confirmed to be causally important.…”