Macronutrient composition of a morning meal and the maintenance of attention throughout the morning

Abstract

Background: At present, the impact of macronutrient composition and nutrient intake on sustained attention in adults is unclear, although some prior work suggests that nutritive interventions that engender slow, steady glucose availability support sustained attention after consumption. A separate line of evidence suggests that nutrient consumption may alter electroencephalographic markers of neurophysiological activity, including neural oscillations in the alpha-band (8-14 Hz), which are known to be richly interconnected with the allocation of attention. It is here investigated whether morning ingestion of foodstuffs with differing macronutrient compositions might differentially impact the allocation of sustained attention throughout the day as indexed by both behavior and the deployment of attention-related alpha-band activity.

Methods: Twenty-four adult participants were recruited into a three-day study with a cross-over design that employed a previously validated sustained attention task (the Spatial CTET). On each experimental day, subjects consumed one of three breakfasts with differing carbohydrate availabilities (oatmeal, cornflakes, and water) and completed blocks of the Spatial CTET throughout the morning while behavioral performance, subjective metrics of hunger/fullness, and electroencephalographic (EEG) measurements of alpha oscillatory activity were recorded.

Results: Although behavior and electrophysiological metrics changed over the course of the day, no differences in their trajectories were observed as a function of breakfast condition. However, subjective metrics of hunger/fullness revealed that caloric interventions (oatmeal and cornflakes) reduced hunger across the experimental day with respect to the non-caloric, volume-matched control (water). Yet, no differences in hunger/fullness were observed between the oatmeal and cornflakes interventions.

Conclusion: Observation of a relationship between macronutrient intervention and sustained attention (if one exists) will require further standardization of empirical investigations to aid in the synthesis and replicability of results. In addition, continued implementation of neurophysiological markers in this domain is encouraged, as they often produce nuanced insight into cognition even in the absence of overt behavioral changes. ClinicalTrials.gov Identifier: NCT03169283.

Keywords: Alpha-band; Attention; Breakfast; Cognition; EEG; Oscillations; Vigilance.

Conflict of interest statement

Conflicts of interest The views expressed in this manuscript are those of the authors and do not necessarily reflect the position or policy of Pepsi-Co Inc. Dr Wilson received partial support from a National Institute of General Medical Sciences (NIGMS) Medical Scientist Training Program Grant (T32 GM007288).

Figures

Figure 1

Experimental layout of the study. (a) shows the key experimental time points across the experimental day, color-coded by the type of event. Task Block refers to a large block composed of several smaller blocks of the Spatial CTET (described in the section ‘Methods’). Except for the UDTR (U) and Baseline (b) Task Blocks, each Task Block was composed of five smaller Spatial CTET blocks. The Baseline block was composed of two Spatial CTET blocks; the UDTR block was also composed of 2, but as it is the task titration block, it was only run on the first day of the study (on the second and third days of the study, it was replaced with the Foil Task). VAS refers to the Visual Analog Scales collected across the course of the day. Practice blocks were administered only on the first day. (b) shows the caloric values of the breakfast interventions employed in the current study. The water intervention (680 ml of water, volume-matched to the oatmeal breakfast) is not shown as it has no caloric value.

Figure 2

Instruments and conventions used for the study. (a) is a depiction of the Spatial CTET presented in monitor coordinates. Two checkerboards were presented along with a central, black fixation point. All other items (axes, boxes, angular measurements, etc.) are presented to the reader to illustrate task structure but are not presented during the task. Only one stimulus configuration (left checkerboard stream at 1.5 Hz; right at 1.3 Hz) is shown. Subjects covertly attended one checkerboard stream (left or right) for the duration of a block (~3 minutes) and reported the appearance of infrequent duration deviants (shown in yellow) via mouse click. Gray and yellow boxes denote the moments at which new orientations of each checkerboard were presented. (b) shows a sample VAS prompt (not to scale). Subjects responded by making a solid vertical line through the spectrum between the two extremum values. (c) shows the electrode pools used to construct measurements on the electrophysiological data. Nine sensors were selected for both left and right posterior scalp where alpha oscillations are known to be detected.

Figure 3

Behavioral analyses by breakfast condition. Sample means ± standard errors are marked by opaque dots with error bars. Transparent lines behind the error bars indicate standard deviations. Raw data are shown in light, colored dots in the background. (a) (Hit Rate) and (b) (False Alarm Rate) are shown as a percentage of total targets/standards presented, respectively. Note the change in y-axis between these two metrics. (c) shows average Reaction Time in seconds over the course of the day, while (d) shows Perceptual Sensitivity (d′).

Figure 4

Subjective reports by breakfast condition. Values from 0 to 100 mm are plotted as a function of experimental block. For each panel, the relevant survey question is printed above the graph, and the two extremum answers are plotted along the side. As before, sample means ± standard errors are marked by opaque dots with error bars. Transparent lines behind the error bars indicate standard deviations. Raw data are shown in light, colored dots in the background. (a)–(d) each correspond to one of the subjective questions asked of participants.

Figure 5

Metrics of alpha oscillations by breakfast condition. As before, sample means ± standard errors are marked by opaque dots with error bars. Transparent lines behind the error bars indicate standard deviations. Raw data are shown in light, colored dots in the background. (a) shows the LTA metric (Logarithm of the Tonic Alpha power) over the experimental day as a function of breakfast condition; (b) shows the ALI metric (Alpha Lateralization Index) in the same fashion.