Acute personalized habitual caffeine doses improve attention and have selective effects when considering the fractionation of executive functions

Abstract

Caffeine is widely used, often consumed with food, and improves simple and complex/executive attention under fasting conditions. We investigated whether these cognitive effects are observed when personalized habitual doses of caffeine are ingested by caffeine consumers, whether they are influenced by nutriments and if various executive domains are susceptible to improvement. This was a double-blind, placebo-controlled study including 60 young, healthy, rested males randomly assigned to one of four treatments: placebo fasting, caffeine fasting, placebo meal and caffeine meal. Caffeine doses were individualized for each participant based on their self-reported caffeine consumption at the time of testing (morning). The test battery included measures of simple and sustained attention, executive domains (inhibiting, updating, shifting, dual tasking, planning and accessing long-term memory), control measures of subjective alterations, glucose and insulin levels, skin conductance, heart rate and pupil dilation. Regardless of meal intake, acute habitual doses of caffeine decreased fatigue, and improved simple and sustained attention and executive updating. This executive effect was not secondary to the habitual weekly dose consumed, changes in simple and sustained attention, mood, meal ingestion and increases in cognitive effort. We conclude that the morning caffeine "fix" has positive attentional effects and selectively improved executive updating whether or not caffeine is consumed with food.

Effect of single caffeine intake on neuropsychological functions in healthy volunteers: A double-blind placebo-controlled study

“…Another finding of the present study was that a single instance of caffeine intake significantly shortened the response time in the Harsh-braking test, which is consistent with the finding that caffeine increases mental arousal[ 27 ]. A driver’s recognition and error in judgment are factors associated with a traffic accident.…”

Effect of Caffeine on the Fixation Component of Eye Movement in the Reading Process

“…Also, these results are consistent with the results of some other studies [5,9,15], that showed caffeine can improve the brain's executive functions. In addition, these results are in line with the result of Lanini et al study, which shows that caffeine causes an increase in information processing speed [7]. So consuming a cup of coffee before studying is recommended.…”

“…Caffeine consumption can also promote the cognitive and executive functions of the human brain [5]. An increase in selective attention and information processing speed has also been reported after drinking beverages containing caffeine [7,14]. The effectiveness of caffeine on cognitive functions was also observed using MRI [8,15].…”

Vigilance Decrement and Enhancement Techniques: A Review

“…It showed that consuming 200 mg of caffeine alone can significantly and consistently improve the number of correct responses while decreasing the reaction time to stimuli compared to placebo over two hours of testing. Meanwhile, Lanini et al [164] reported that personalized individual caffeine dosages from 25 mg to 300 mg improved the vigilance of 60 young adults who performed psychomotor vigilance task. In this study, caffeine has significantly reduced the mean reaction time and led to less variable response times from the beginning until the end of a 10-minute performance of vigilance task.…”

“…The highest improvements (more than +15%) on monotonous vigilance tasks were reported when video game and transcranial direct current stimulations were used [32,33,49,52]. Haptic stimulation (HPS), modafinil, cognitive work-modulation (CWM), tACS, chewing gum (CG), and caffeine [28,29,35,38,46,164,206] showed an improvements of more than +%10. However, music, binaural beats (BBs), and fragrance produced improvements of equal or less than +10% in the simple monotonous vigilant tasks [41,123,124,125,193].…”