Abstract
Acute caffeine intake has been found to increase working memory (WM)-related brain activity in healthy adults without improving behavioral performances. The impact of daily caffeine intake—a ritual shared by 80% of the population worldwide—and of its discontinuation on working memory and its neural correlates remained unknown. In this double-blind, randomized, crossover study, we examined working memory functions in 20 young healthy non-smokers (age: 26.4 ± 4.0 years; body mass index: 22.7 ± 1.4 kg/m2; and habitual caffeine intake: 474.1 ± 107.5 mg/day) in a 10-day caffeine (150 mg × 3 times/day), a 10-day placebo (3 times/day), and a withdrawal condition (9-day caffeine followed by 1-day placebo). Throughout the 10th day of each condition, participants performed four times a working memory task (N-Back, comprising 3- and 0-back), and task-related blood-oxygen-level-dependent (BOLD) activity was measured in the last session with functional magnetic resonance imaging. Compared to placebo, participants showed a higher error rate and a longer reaction time in 3- against 0-back trials in the caffeine condition; also, in the withdrawal condition we observed a higher error rate compared to placebo. However, task-related BOLD activity, i.e., an increased attention network and decreased default mode network activity in 3- versus 0-back, did not show significant differences among three conditions. Interestingly, irrespective of 3- or 0-back, BOLD activity was reduced in the right hippocampus in the caffeine condition compared to placebo. Adding to the earlier evidence showing increasing cerebral metabolic demands for WM function after acute caffeine intake, our data suggest that such demands might be impeded over daily intake and therefore result in a worse performance. Finally, the reduced hippocampal activity may reflect caffeine-associated hippocampal grey matter plasticity reported in the previous analysis. The findings of this study reveal an adapted neurocognitive response to daily caffeine exposure and highlight the importance of classifying impacts of caffeine on clinical and healthy populations.
| Original language | English |
|---|---|
| Article number | 1002 |
| Journal | Scientific Reports |
| Volume | 13 |
| Issue number | 1 |
| ISSN | 2045-2322 |
| DOIs | |
| Publication status | Published - 12.2023 |
Funding
This study is funded by Swiss National Science Foundation (Grant 320030-163058). We express our sincere appreciation to our interns Andrea Schumacher and Laura Tincknell, M.Sc. student Sven Leach and Joshua Kistler, as well as all the study helpers for their assistance in the experiment and data processing. We also thank Dr. Corrado Garbazza and Dr. Martin Meyer for the health check during screening process. We are grateful for the assistance and resources provided by Professor Katharina Rentsch and Dr. Sophia Rehm at the Laboratory Medicine, University Hospital Basel. We especially appreciate all our participants for their volunteering and cooperation.
Research Areas and Centers
- Academic Focus: Center for Brain, Behavior and Metabolism (CBBM)
DFG Research Classification Scheme
- 2.23-04 Cognitive, Systems and Behavioural Neurobiology
- 2.23-08 Human Cognitive and Systems Neuroscience
