Insufficient vitamin B6 is linked to cognitive impairment, and a new study presents a novel approach to maintaining adequate B6 levels. The enzyme is pyridoxal phosphatase (PDXP). Neuropsychologists say that several studies have examined the impact of B6 on cognition. Specifically maintaining adequate levels of B vitamins, and vitamin B6 in particular, is essential for optimal neurotransmitter synthesis and homocysteine metabolism, and thus may have a direct impact on cognitive function.
The hippocampus is believed to be important for age-dependent memory consolidation and learning and, therefore, cognition. Cognitive dysfunction is a cardinal symptom of depression, particularly deficits in attention and psychomotor speed. So far, the benefits of enhancing levels of B6 via supplementation as a therapeutic method are unclear. Clinical trials have yielded mixed results, particularly in areas that correlate with hippocampal functioning. The new study may help explain that. Gohla said her team found that “PDXP is substantially upregulated or strengthened in the hippocampus of middle-aged people compared to young mice.”
This aligns with age-related memory loss that occurs with ageing. This suggests that a therapeutic vitamin B6 supplementation alone may not be sufficient to elevate the levels of B6 in the brain — simply because the supplemented B6 would be immediately degraded by hyperactive PDXP. In contrast the study finds combining B6 supplements with PDXP inhibitors that block B6 degradation may be much more effective in boosting cellular B6 levels. In the team’s previous work, they found the spatial learning and memory capacity of mice was improved when PDXP was genetically switched off. Their performance was compared to mice with PDXP intact.
The researchers assessed the cognitive functioning of mice using a Barnes maze that provides a means to measure hippocampus-dependent spatial reference memory by evaluating the ability to learn and remember the location of a hidden escape zone using a set of visual cues.
In the “maze,” mice are placed on a platform with unpleasantly bright lighting. While there were several possible “escape” holes for the mice on the platform, only some were available for use. Given the differences between mice and humans, there may be concerns that the study’s findings will not be applicable to people.The two functions of B6 in cognition mentioned i.e., neurotransmitter synthesis and homocysteine metabolism are thought to be mechanistically interchangeable between mice and humans. So, it is conceivable that the research would translate barring obvious environmental confounders (e.g., alcohol consumption, poor diet, etc.).
