Five Years Later - How Much of Our EEG Is Still “Us”?

Five years is a long time.

We change routines. We learn. We forget. We alter habits, relationships, metabolism, sleep, work, diet, expectations, and perhaps even the way we perceive ourselves.

But if we recorded our EEG today and repeated exactly the same procedure five years from now, what would still look similar enough to be recognized as part of an individual trajectory?

That is the question that makes the work of Polina Politanskaia and colleagues especially interesting, published in 2026 in Cerebral Cortex.

In Long-term reliability and stability of parameterized resting state EEG: evidence from a five-year follow-up, the authors investigated the reliability and stability of periodic and aperiodic resting-state EEG parameters over approximately five years. The goal was not simply to determine whether EEG “stays the same,” but whether some characteristics remain consistent enough to distinguish individuals while others track changes related to time and aging.

The question sounds almost contradictory:

how can something remain reliably “ours” while also changing?

Perhaps that is precisely the most interesting part of the study.

A question that required waiting five years

Much of the research on EEG reliability compares recordings separated by days, weeks, or months.

Those studies are essential for determining whether a measure can be reproduced.

But if we want to use EEG to investigate aging, cognitive change, or possible pathological trajectories, we need to know what happens over much longer timescales.

Politanskaia and colleagues analyzed adults assessed at two time points separated by approximately five years and parameterized their resting-state EEG spectra.

Among the measures they examined were:

aperiodic exponent, aperiodic offset, parameterized alpha power, and individual alpha peak frequency.

The distinction between periodic and aperiodic components is important.

For decades, much of EEG interpretation focused on classical frequency bands such as delta, theta, alpha, beta, and gamma.

Today, we know that the spectrum also contains an aperiodic structure — approximately resembling a 1/f pattern — that should not simply be treated as background noise.

By separating these components, we can ask not only how much alpha is present, for example, but whether an apparently oscillatory change may in part reflect a change in the spectral background itself.

Five years later, part of the configuration was still recognizable

The results showed fair-to-excellent test–retest reliability for the parameters examined.

That means that although five years had passed, individual differences had not disappeared completely. People who occupied particular relative positions on a parameter during the first assessment often remained recognizable in relation to the group at the second assessment.

But this did not mean immobility.

The individual alpha peak frequency decreased over time.

The aperiodic exponent became flatter.

The study also found changes in the aperiodic offset, while parameterized alpha power showed greater stability.

And here an important distinction appears:

stability does not mean remaining identical.

Perhaps stability is precisely the capacity to change without completely losing a recognizable trajectory.

A window: perhaps we always think we have finally finished changing

There is a classic psychology study that makes these findings even more provocative.

In 2013, Jordi Quoidbach, Daniel Gilbert, and Timothy Wilson published The End of History Illusion in Science.

The researchers studied more than 19,000 people between the ages of 18 and 68, examining personality, values, and preferences. Some participants estimated how much they had changed over the previous ten years; others predicted how much they expected to change over the next ten.

The result revealed a curious asymmetry.

People readily acknowledged substantial change in their own past.

But they predicted considerably less change in their future.

It was almost as if we tend to think:

“I changed a lot to get here; now I am finally who I will continue to be.”

Quoidbach, Gilbert, and Wilson called this phenomenon the End of History Illusion.

The authors also suggested an interesting possibility: imagining a future self who differs from our current one requires cognitive effort. We may therefore confuse the difficulty of imagining future change with the improbability that such change will actually occur.

This creates a fascinating bridge to EEG.

The two studies investigate completely different things, and one should not be presented as confirmation of the other.

Quoidbach and colleagues studied how we perceive and predict our own change.

Politanskaia and colleagues studied how neurophysiological characteristics actually behave over five years.

But placed side by side, they generate an intriguing question:

what if our sense of stability is greater than the material stability of the configurations that continuously sustain us?

Alpha also moves through time

Individual alpha peak frequency is one of the most studied characteristics of human EEG.

It differs across individuals and also changes with factors such as age and functional state.

Politanskaia and colleagues found a reduction in this frequency over the five-year interval.

We should not translate this simply as “the brain became slower.”

That would be too broad an interpretation.

The finding shows something more careful: an individual spectral characteristic can simultaneously display reliability and follow a temporal trajectory.

The same reasoning applies to the aperiodic component.

There may not be a single signal that we can call “the EEG of aging.”

Different properties change in different ways.

And perhaps it is precisely this multiplicity that allows EEG to track trajectories rather than provide only a snapshot.

Body-Territory: five years enter the second EEG

Between the first and second recordings, more than five calendar years have passed.

There have been five lived years.

Sleep.

Stress.

Exercise.

Learning.

Relationships.

Environments.

Illnesses.

Medications.

Losses.

New experiences.

The study cannot determine how much each of these dimensions contributed to the observed changes.

But from a Body-Territory perspective, this reminds us that the second EEG does not simply encounter “the same brain, five years older.”

It encounters an organism that has moved through five years of territory.

The Body returning to the laboratory remains continuous with the one that was there before.

But it does not need to be the same configuration.

How much of EEG is “me”?

We need to be careful here.

EEG is not identity.

An alpha frequency is not the subject.

The aperiodic exponent is not “the self.”

These parameters are transductions of aspects of neural activity.

But their longitudinal stability allows an interesting question:

how much of a particular neurophysiological configuration can accompany a Body through time?

And, conversely:

how much can it change while we still recognize a trajectory?

This question also has clinical relevance.

If we can better understand expected trajectories of aging, changes that deviate from them may eventually help identify atypical processes.

That requires larger studies, replication, and continued longitudinal follow-up. But this is precisely why establishing long-term reliability matters.

5D Consciousness: Being does not require repeating the previous state

For our proposal of 5D Consciousness, this work offers a particularly fertile analogy.

Being does not need to mean remaining in the same configuration.

The current state may carry enough history for continuity to exist without being an exact repetition of the previous state.

In this sense:

continuity ≠ immobility.

An organism can change continuously and still perceive itself as the same one.

This also helps reinterpret the End of History Illusion.

Perhaps what we perceive today as our relatively final version is simply the configuration from which we are currently able to imagine the future.

Being unable to imagine who we might become does not mean that the Body-Territory is incapable of becoming another configuration.

The present may be just another transitional state

The study by Politanskaia and colleagues shows something apparently simple but deeply interesting.

Five years later:

some characteristics remain recognizable;

others change;

and both can belong to the same individual.

Perhaps biological identity does not depend on preserving a state.

Perhaps it depends on preserving enough continuity through transformation.

And perhaps the more interesting question is not:

“how much of me stayed the same?”

but:

“how much can I change and still recognize the trajectory as mine?”

The End of History Illusion suggests that we often look backward and see movement, but look forward and imagine arrival.

Longitudinal EEG offers another image:

the present is passing too.

Today’s Body-Territory does not need to be the final version of the one we will perceive ourselves to be tomorrow.

Some characteristics may remain.

Others will encounter new movements.

And perhaps consciousness is also this:

enough stability to perceive continuity, and enough openness to still be able to change.

References

Politanskaia, P., Bywater, J., Finley, A. J., Keage, H. A. D., Kelley, N. J., McKeown, D. J., Schinazi, V. R., & Angus, D. J. (2026). Long-term reliability and stability of parameterized resting state EEG: evidence from a five-year follow-up. Cerebral Cortex, 36(7), bhag113. https://doi.org/10.1093/cercor/bhag113
Shows that periodic and aperiodic EEG parameters can remain sufficiently reliable over approximately five years while also displaying systematic changes associated with the passage of time.

Quoidbach, J., Gilbert, D. T., & Wilson, T. D. (2013). The End of History Illusion. Science, 339(6115), 96–98. https://doi.org/10.1126/science.1229294
In more than 19,000 participants aged 18 to 68, showed that people tend to recognize how much they changed in the past while underestimating how much they may still change in the future, offering a useful bridge between perceived continuity and actual transformation.