Functional MRI (fMRI) is still one of the most popular methods to study the ageing brain. Getting older affects both the structure of the brain and our cognitive capabilities but there is still no solid evidence on how ageing influences the mechanisms underlying the fMRI signal. Here, we apply a recently developed fMRI-based sequence that was found to be sensitive to quantum fluctuations in the brain. We show that not only these fluctuations can be detected and measured, but also that they are affected by age. While comparing young and old participants, we found qualitative and quantitative evidence that the dynamics of these quantum fluctuations undergo strong changes with age. Finally, we show how differences in these quantum fluctuations relate with measures from different cognitive batteries, suggesting that these quantum fluctuations may be key for cerebral dynamics and cognitive functioning. The profound sensitivity for dynamic changes shows the potential of this physiological effect with clinical relevance for all neuro-vascular diseases.