Elevated functional magnetic resonance imaging activity in cognitively normal participants predicts future dementia.

As individuals age, they are more likely to show increased functional MRI (fMRI) activity, particularly in frontal regions. This has been interpreted as a compensatory mechanism, yet the very need to draw upon such resources indicates increasing failures of brain systems. Almost all work addressing theoretical models explaining these patterns has been cross-sectional, with minimal work testing how elevated fMRI activity predicts future cognitive trajectories. Further, although often viewed as ageing, there is increasing evidence that subtle fMRI changes may represent the earliest manifestation of neurodegenerative conditions such as Alzheimer's disease. One hundred nine individuals completed a Stroop colour/word task during fMRI data acquisition. Analyses focused on differences between trials where the colour and word were incongruent (the word red written in blue) relative to congruent trials (the word blue written in blue). At baseline, participants also underwent amyloid positron emission tomography imaging and