Table 1.
Summary of studies included in the systematic review which used electroencephalography (EEG). Including evoked response potential (ERP) components. WS = Within-subject, repeated measures (crossover) design; BS = Between-subject design; N = Number of participants; ↑ or ↓ indicates glucose-related improvement or decrease, respectively; ACC = Anterior cingulate; DLPFC = Dorsolateral prefrontal cortex; FPN = Frontoparietal Network; SN = Salience Network; QR = Quality rating based on modified Jadad Scale. Studies are listed in the order they appear in the manuscript
| Reference | Design | N | Participants | Fasting | Glucose | Placebo | Task | Behavioral Results | Neuroimaging Results | QR (/10) |
|---|---|---|---|---|---|---|---|---|---|---|
| EEG/ ERP P3b | ||||||||||
| (Riby et al., 2008) | WS | 11 | Healthy young adults mean age 28.7 ± 6 (5 m/6f) | 2 h | 25 g | 38 mg saccharin | Visual 3-stimulus oddball task | No treatment effect. | ↓ Reduced P3b amplitude | 6 |
| (Knott et al., 2001) | WS | 10 | Elderly subjects mean age 62.7 ± 5.7 (9 m/1f) | overnight fast | 50 g glucose +4 mg saccharin | 50.6 mg saccharin | Sternberg memory scanning task (assesses speed and efficiency of short-term memory storage and processing) | No treatment effect. | No treatment related effect. | 7 |
| EEG/ ERP LP/ FN400 | ||||||||||
| (Brown & Riby, 2013) | BS | 18 glucose; 17 placebo | Young adults mean age 22.17 ± 5.97 (14 m/21f) | 2 h | 25 g | 37.5 mg saccharin | Episodic memory (item recognition task, words and pictures); Attention (Stroop) Task | ↑ Increased accuracy during episodic memory | ↑ Enhanced LP effect | 7 |
| (Smith et al., 2009) | WS | 17 | Healthy adolescents mean age 14.4 ± 1.5 (9 m/9f) | 2 h | 25 g | 5 of aspartame tablets | Recognition memory task | ↑ Faster response times | ↑ Enhanced LP; ↑ Enhanced FN400 | 5 |
| (Scholey et al., 2015) | WS | 12 | Healthy elderly mean age 69.33 ± 1.69 (7 m/5f) | overnight fast | 25 g | 30 mg saccharin | Word recognition: remember-know paradigm both with and without psychomotor tracking during auditory presentation of words) | ↓ Reduced overall accuracy | ↑ Enhanced LP effect | 8 |
| EEG/resting state | ||||||||||
| (Knott et al., 2001) | WS | 10 | Elderly subjects mean age 62.7 ± 5.7 (9 m/1f) | overnight fast | 50 g glucose +4 mg saccharin | 50.6 mg saccharin | Eyes closed, 6 min vigilance-controlled EEG acquisition | No treatment effect. | No treatment related effect. | 7 |
| (An et al., 2015) | WS | 24 | Healthy adults mean age 33.1 ± 2.6 (11 m/13f) | ≥ 8 h | 17 g | none | Digit span: Wechsler Adult Intelligence Scale revised; Spatial span test: Corsi block-tapping test | ↑Improvements in attentional performance | ↑ Increased power in theta and low alpha bands on resting-state EEG | 4 |