Acute effects of brewed cocoa consumption on attention, motivation to perform cognitive work and feelings of anxiety, energy and fatigue: a randomized, placebo-controlled crossover experiment

Abstract

Background: Acute effects of caffeinated and non-caffeinated cocoa on mood, motivation, and cognitive function are not well characterized. The current study examined the acute influence of brewed cocoa, alone and with supplemental caffeine, on attention, motivation to perform cognitive tasks and energy and fatigue mood states. Methods: A randomized, double-blinded, within-subjects crossover trial was conducted with four 473-milliliter brewed beverage treatments: cocoa, caffeinated cocoa (70 milligrams caffeine total), placebo (flavored and colored brewed water) and positive control (placebo plus 66 milligrams caffeine, "caffeine alone"). Participants (n = 24) were low consumers of polyphenols without elevated feelings of energy. Before and three times after beverage consumption, a 26-minute battery was used to assess motivation to perform cognitive tasks, mood and attention (serial subtractions of 3 and 7, the continuous performance task, and the Bakan dual task) with a 10-minute break between each postconsumption battery. The procedure was repeated with each beverage for each participant at least 48 h apart and ±30 min the same time of day. Data were evaluated using Treatment X Time analysis of covariance controlling for hours of prior night's sleep. Results: Compared to placebo, cocoa reduced overall false alarm errors progressively across time with 0.92, 1.44 and 2.35 fewer false alarms on average 22-48, 60-86 and 98-124 min post-consumption (η 2 = 0.08, p = 0.019). Caffeinated cocoa: (i) attenuated the anxiety-provoking effects of cognitive testing found after drinking caffeine alone (η 2 = 0.064, p = 0.038), and (ii) increased accuracy (η 2 = 0.085, p = 0.01) and reduced omission errors (η 2 = 0.077, p = 0.016) on the Bakan primary task compared to cocoa alone.

The effects of polyphenols and other bioactives on human health

“…131 In another recent randomized, controlled, cross-over study by Boolani et al, the addition of caffeine to cocoa may have acted to improve accuracy and reduce omission errors on the Bakan primary task. 132 However, due to the inclusion of a control group that did not receive caffeine, it is difficult to differentiate the effects of the caffeine from the cocoa polyphenols. There is also a large body of research that attributes the cognitive effects of tea and coffee to caffeine without any consideration for any contribution from polyphenols.…”

Sleep quality and sex modify the relationships between trait energy and fatigue on state energy and fatigue

“…To capture this distinction, the mental and physical state and trait energy and fatigue scale was used [26]. The reliability of this scale has been supported by prior analyses [3,3,4,27]. The trait scale is a 12-item measure with 3 items per trait to measure the disposition of mental energy, mental fatigue, physical energy, and physical fatigue.…”

“…Representative statements included: "I feel I have energy" and "I have feelings of being worn out." The state component had the same 12 items as the trait scale, except that they were measured on a 0 to 10 scale and referred to present state [27]. Among healthy adults, the Cronbach's alpha coefficients range from 0.82-0.91 [26].…”

“…The Profile of Mood Survey-Short Form (POMS-SF) was used to measure feelings of depression, anxiety, anger, and confusion [28]. Polyphenol and caffeine consumption were measured using surveys that asked subjects about their consumption of different fruits, vegetables, beverages and chocolates [27]. Heightened polyphenol consumption, especially over a long period, has been found to predict moods [29], including trait energy and fatigue [23].…”

“…Additionally, we measured current state mental and physical energy and fatigue while the sleep quality measures were for a 30-day span. Current mood states may be influenced by immediate events [27,32]. We also opted to use an aggregate measure of sleep quality instead of examining each component of the PSQI.…”