In the future the technology to reverse one's age exists. We can make people younger but not older. One day there is an accident, and someone is reverted to a ten year old, instead of reverting to their mid twenties.

Is it realistic to suppose that the differences between child and adult brains are so that making an adult into a child will leave their memories confused and distorted? As opposed to simply reverting an adult into a youthful state (turning a fifty year old into a twenty five year old)? How is this likely to manifest? For example, would it be like a weird sort of childhood dementia which improves with time?

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    $\begingroup$ We don't know, we can only speculate. I don't think you should ask for and expect hard science. $\endgroup$ – Raditz_35 Sep 7 '17 at 12:57
  • $\begingroup$ @Raditz_35 I completely disagree. There's a difference between an answer which says, well I think this is so, and another which says; well according to X the difference between child an adult brains are thus, which is/not significant. Therefore it is possible that... because we know according to Y that as the brain ages it does Z, so in reverse that would be likely. $\endgroup$ – inappropriateCode Sep 7 '17 at 13:02
  • $\begingroup$ You do not understand my comment. I'm not saying this isn't a question which could potentially be answered scientifically, I'm saying we don't know enough to answer such specific questions. How would one even go about investigating this? $\endgroup$ – Raditz_35 Sep 7 '17 at 13:06
  • $\begingroup$ @Raditz_35 Are you saying the science-based tag is more appropriate than the hard-science? Or that it isn't possible to answer because you don't see how it could be done? I've seen too many responses to various answers here with people effectively saying, I can't see how this can be done, therefore it's impossible. Which is really frustrating and not constructive. $\endgroup$ – inappropriateCode Sep 7 '17 at 13:08
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    $\begingroup$ You might be interested in Rainbows End by Vernor Vinge. The main character is an old man cured of Alzheimer's disease, but in doing so he is physically reverted to a teenager. To catch up on the last 20 years he's missed, he goes back to school. It's not quite going back to being 10, but it might provide inspiration. $\endgroup$ – Schwern Sep 7 '17 at 19:02

It really depends on the way your age reversal tech works. Assuming 2 broad categories we could get to the following conclusions:

Cat. A) Age-Reversal does actually reverse

Assuming the process of reversal does actually techno-magically reverse everything the body went through back to a certain point in time. It wouldn't be far-fetched to assume that memory and experiences would be reversed (or reset) back to that point in time in the bodies history.

A person would thus have to record their memories and accomplishments externally in order to teach themselves whatever they find most important of the time they will lose during the process.

This would affect a person being reset to a 10 year old instead of their mid-twenties drastically, as this means that the person would go through their teens again and thus relive the whole process of becoming a person and building a character that will crassly influence their future life.

From my dabbling into psychology and the process of becoming an adult it seems very probable that this would negatively affect the person in various ways. One of these ways (and the only I feel confident enough in my knowledge to elaborate) would be the strong feeling of betrayal and abandonment - the world has drastically changed in comparison to what one remembers; ones parents are some 40 years older than one thought to know - or might even be dead; it is likely that the only childhood/teenhood this person is going to know will be from the memories a future-past-self has recorded, as well as from literature and media.

Cat. B) Age-Reversal is just a fancy term for cell- & tissue regeneration

Assuming the process of reversal is just a fancy brochure for regenerative treatment of the bodies cells it seems unlikely that any memories would be lost. It seems questionable and even dangerous to alter brain-chemistry if there's no alternative ways of properly storing & restoring memories.

The effect would be a 50-ish year old person in the body of an early teen.

Assuming that society is already properly attuned to age-reversal I can only imagine that the person would relish and delight at the chance to live through the hardest time of their life and this time know that it will all end well even if Amanda doesn't like me the way I like her.



Would the 10-year-old be expected to go through school again? If you had enough childhood experience/expectations forced upon you, it may begin to overwrite some of the memories (if you're treated in a certain way, then you begin to act accordingly).

Also, if you're in a pre-pubescent body, hormonal changes haven't yet happened, so reconciling sexual desires and complex emotional relationships simply may not tally with the chemical and neurological structure of a young child. Perhaps some kind of preservation instinct would kick in - the brain may try to categorise the memories as some kind of distant dream in order to avoid emotional trauma.

But I imagine that this 10-year-old would have to grow up very quickly in order to process more fully the kind of experiences their 50-year-old self had - and may not recover so well. Then again, if your society is used to doing this (e.g. there are counselling sessions that go hand-in-hand with this age-reversal treatment), it's possible that people are conditioned enough to expect some kind of psychological dysphoria that this gets treated in a similar way.


If a 50-year-old gets put back into their pre-pubescent body, they may become quite uncoordinated for a short time. Children adapt very quickly (and adults are still surprisingly fast!), so they'd probably get better very soon, but changes in height, weight, strength, limb ratio, strength-to-weight ratio, etc. could be confusing for a while.


Are different laws in place for those who have age-reversal treatment? Would a recently-remade 20-year-old have to pay car insurance premiums for a normal 20-y-o, or would no claims discount carry over? Would your 10-year-old be treated like a minor in the eyes of the law, or like a adult? Could they see adult films, listen to parental advisory lyrics, need a chaperone at a theme park, be allowed to drive?

I imagine it would be a bit of a shock to see a child behind the wheel of a Ferrari, but I suppose they could have certificates proving their reversed-age identity. But this may also end up with other children/teenagers trying to get away with stuff by faking ID that shows they had age-reversal treatment.

  • $\begingroup$ They won't need a paper certificate to prove age reversal. If they have this technology, then the genetic reversal marker will be present in all their cells. A quick painless skin prick and they will show up positive on the revids (slang for Reversal-ID monitors) that became commonplace at any age-monitored activity/marketplace. $\endgroup$ – N2ition Sep 8 '17 at 1:55

Reversing the age of the brain to 10 years old can not be done lossless.

At 10 years old, human brain is not fully grown, neurons are still dividing and links between them are actively changing. Even at 20-25 years of age, brain is still developing (though no new neurons are born). So, we have to define how our age-reversal process works on the brain.

  1. Full reversal. This means the brain would completely return to its state at the target age. We don't know very well how memories are stored, but there is a very good chance that a lot of memories would be erased in full reversal process;
  2. Full preservation. This means that all brain cells and links between them are preserved as the age reversal happens. Now the memories will be secure, however it is not clear how beneficial this process (or lack of a process) would be for the brain. We will end up with an adult brain in young body.
  3. Hybrid approach. This is not scientific at all, but imagine there is a way to make brain younger without losing any memories. In this case, we would be able to turn an adult into a truly 10 years old. There we have a lot of examples in popular fiction as to what might happen.

There isnt enough knowledge to know what exactly will happen here.

However, memories are memories and a 10 year old would certainly be capable of retaining an adult's memories as they themselves can remember things. A baby however..... not sure.

Behaviorally...... There is plenty of science to support the brain's development affects behavior at different stages. As humans, nurture (ie experience) can in many cases win out over nature. What most likely will happen here is the subject will experience intense urges and based on their experience decide what to do which might alter personality to some degree.

So the answer to the second question is raw impulses


Death! Attempting to somehow reverse a person into the body of a ten year old would almost certainly kill them. The only way to get around this would be time travel, or ludicrously complicated technology designed to intentionally turn someone into a child. (And we're talking massive surgeries, manipulation on the cellular level, probably a lot of tissue grafting from a younger clone, or maybe it would be easier to just transplant their brain in to a young clone.)

I assume your age reversal is supposed to turn back our "Biological clock?" If this is the case reverting someones biological clock to how it was when they were 10 would not only not shrink them back to a 10 year old, it would start them growing again, and the growth would likely prove lethal, as a human heart is not capable of supporting such a large person. (People who have pituitary issues and don't stop growing become vert ill and die.)


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