Individual Alpha Frequency (IAF) and Cognition: Potential as a Clinical Marker and Constraint for Personalized...

The individual alpha frequency (IAF) refers to the frequency at which the alpha rhythm shows peak power. This index is of great interest to neuroscience as it represents a marker of cortical timing and temporal resolution of neural processing. Renewed interest stems from the opportunity to consider IAF not only as a descriptive marker of intrinsic brain dynamics but also as a neural marker serving as a personalized parameter in neuromodulation interventions. In this narrative review, we synthesize empirical and theoretical evidence that supports current understanding of IAF across methodological, biological, cognitive, clinical, and interventional domains. Methodologically, IAF estimation does not follow a uniform approach and would benefit from greater convergence, including explicit separation of the periodic oscillation signal from the aperiodic background. Physiologically, evidence indicates substantial heritability and short-to-medium-term test-retest reliability of IAF, while support for clear and stable structural and neurochemical characteristics is weaker. Cognitively, IAF modulation is associated with specific abilities, depending on the task and cognitive domain. Faster IAF is associated with finer temporal resolution, better attentional and visuospatial performance, and increased processing speed, with more limited and region-dependent evidence for working memory. Clinical and longitudinal evidence suggests that deviations from the expected age-related trajectory, a non-linear rise into early adulthood followed by gradual slowing, accompany pathological aging, neurological, and mental disorders. However, these deviations are graded, indicating how far individuals depart from normative values, rather than providing stand-alone diagnostic cut-offs. Finally, interventional studies on IAF-tuned neuromodulation are consistent with increased transient neural entrainment and improved performance in the context of substantial IAF index stability. This positions IAF as a constraint rather than a target for personalization: an individual-specific resonance range within which stimulation is likely to interact optimally with ongoing dynamics, and a candidate parameter for personalized brain stimulation protocols.