As @Bryan Krause pointed out before me, unless you can regulate adenosine signaling in a selective way any manipulation is probably going to cause important side-effects.
If your goal is to regulate adenosine signaling in a more specific way than caffeine, one way could be to selectively manipulate adenosine receptors of specific pathways. This approach was taken by Blundon et al. (2017) who used a compound that is able to cross the blood-brain barrier (FR194921) to selectively affect cortical map plasticity. It so happens that this compound selectively targets thalamocortical projections, so it could be a promising strategy. But even with such a selective approach side-effects cannot be excluded.
I have contributed a preview article for that study (Kehayas and Holtmaat 2017).
- Blundon, J. A., Roy, N. C., Teubner, B. J. W., Yu, J., Eom, T.-Y., Sample, K. J., … Zakharenko, S. S. (2017). Restoring auditory cortex plasticity in adult mice by restricting thalamic adenosine signaling. Science, 356(6345), 1352–1356. https://doi.org/10.1126/science.aaf4612
- Feldman, D. E., & Brecht, M. (2005). Map plasticity in somatosensory cortex. Science, 310(5749), 810–815. https://doi.org/10.1126/science.1115807
- Kehayas, V., & Holtmaat, A. (2017). Rejuvenating brain plasticity. Science, 356(6345), 1335–1336. https://doi.org/10.1126/science.aan8374