4. Discussion
ADVERSE EVENTS
This investigation sought to examine the effect of the ingestion of methylliberine on cognitive performance and subjective feelings of well-being. The acute ingestion of methylliberine improved concentration, motivation, and mood more profoundly and sustained positive effects for longer than PLA. Furthermore, the acute ingestion of methylliberine may have improved well-being and the ability to tolerate stress, while the short-term supplementation of methylliberine (i.e., after three daily doses) may have improved time to completion on the TMT-B test. On the other hand, there were no acute differences in the cognitive performance measures between PLA and methylliberine. Interestingly, methylliberine had a positive impact on energy and sustained energy for women as compared to men, which may have been driven by differences in body size/weight. There were negligible differences between treatments in terms of vital signs, apart from a higher diastolic blood pressure 2 h post-ingestion during the PLA treatment. Lastly, both treatments were very well-tolerated, without any adverse events reported.To our knowledge, this is the first study evaluating the impact of the independent ingestion of methylliberine on common cognitive function tests. The Stroop test measures working memory and attention control [Methylliberine had a significant positive impact on mood, motivation, and concentration. Notably, an acute 100 mg dose of methylliberine uniquely improved concentration by approximately 10.2% one-hour post-ingestion and approximately 15.3% three hours post-ingestion. Although PLA improved motivation 1 and 2 h post-ingestion and mood 2 h post-ingestion, methylliberine increased motivation 3 h post-ingestion and improved mood 1, 2, and 3 h post-ingestion. Methylliberine also had a larger positive change in mood from baseline to 1 h and 3 h post-ingestion. The consistent improvements in methylliberine at the 3 h mark were notable and unexpected given its short half-life of 1.5 ± 0.8 h [An interesting observation in the current investigation was the notable increases in energy and sustained energy that were unique to women. After an acute dose of methylliberine, women had a greater increase in sustained energy and a potential increase in energy 1 and 3 h post-ingestion relative to baseline vs. PLA. Similarly, Taylor et al. (2016) noted increased levels of vigor from week 4 to week 8 with daily TeaCrineMethylliberine had minimal effects on vitals. In fact, an increase in DBP was noted 2 h after PLA ingestion, while there were no changes over time with methylliberine. Therefore, the current investigation corroborates previous findings showing no effect on hemodynamics with methylliberine ingestion [Given that caffeine and TeaCrineOur study demonstrated that methylliberine did not enhance cognitive function, but did significantly enhance subjects’ perceptions of energy, concentration, motivation, and mood over time. Methylliberine also improved concentration, well-being, and the ability to tolerate stress to a greater degree than PLA, while having no detrimental effects on vital signs (blood pressure and heart rate). Methylliberine also seems to have had a positive impact on the self-reported ratings of sustained energy in women. Although the placebo improved motivation and mood post-ingestion (at hours 1 and 2), methylliberine sustained these benefits for longer (up to 3 h post-ingestion) on the acute testing day (i.e., the fourth dose).