How general anaesthetic affects your brain and body

Sometimes it’s necessary, but you should still know what it does to your body.

Sometimes a general anaesthetic is unavoidable, but when you discover what it does to your brain and body, you may be more likely to go for a local the next time you have a choice.

Research has revealed that older people who have surgery requiring general anaesthetic can take up to six months to get over the anaesthetic alone.

According to a study published on, 35 per cent of older patients who had a general anaesthetic actually increased their risk of developing dementia by 35 per cent.

This may be because the anaesthesia causes inflammation to neural tissues, antagonising the precursors to Alzheimer’s disease.

However, for the times when you do need a ‘general’, it can pay to know how it works, so you know what to expect and how you’ll recover.

Scarily enough, the exact way anaesthesia works is not entirely clear. The drug may work by altering neuronal membranes possibly by making membrane proteins expand. Feeling assured?

Suffice to say that anaesthetics works on many levels at once, acting on several sites in the nervous system and causing analgesia (the inability to feel pain), amnesia and immobility. The drugs range from alcohol to a complex chemical called sevoflurane, which will act on a number of brain sites, such as:

  • the cerebral cortex (acts on memory, attention and perception)
  • thalamus (relays information from sensory receptors to various areas of the brain)
  • the reticular activating system (regulates sleep)
  • the spinal cord (takes signals from the brain to the body)
  • neurotransmitters and receptors, including those that control memory and synaptic functions, hormone regulators and some that govern sleep function. 

So, what does general anaesthesia do to you?

The first stage of anaesthesia is called the induction phase, when you will feel floaty, tingly and light all over. You will feel no pain just prior to losing consciousness.

During the second stage, your body will go through the ‘excitement phase’ – a very short phase when your body will feel panic because it is instinctively trying to ‘save’ you from reacting to the anaesthesia.

Stage three is called ‘surgical anaesthesia’, which is when you fall asleep, although you’re not simply in a deep sleep or unconscious, you’re closer to a comatose state.

The fourth stage is when your nervous system shuts down, and your brain is effectively in a state of impairment, blocking any pain signals or the ability to respond to anything at all.

During this stage, your brain won’t even be able to communicate with itself, as the drug will calm the flow of chaotic electrical signals to a point where they are so calm that your entire body follows suit.

The anaesthesia will also prevent the flow of neurological and electrical activity through your spine, effectively paralysing you.

Now, all this sounds harrowing but you’ll be monitored very closely by a dedicated member of a surgical team – the anaesthesiologist.

Once you’re out from under an anaesthetic, your brain needs to restart. It’s not as simple as just waking up. Your brain will wake in one area, then another and once enough parts of your brain awaken, it will then try to re-start the connections to get things firing again. During this phase, you may feel a little ‘crazy’.

And when you first ‘wake up’ all of your body parts may not work properly, but with a little time, they should all come back online and, chances are, you won’t remember any part of this phase or any previous stages – or if you do, it will be extremely vague.

For one in every one thousand instances of anaesthesia, a patient may experience ‘Anaesthesia Awareness’ where they may recall aspects of their procedure, including pain and sensations such as fear and discomfort. This happens when drugs are administered incorrectly, but this is so rare that you shouldn’t let it dissuade you from anaesthesia.

As you can see, general anaesthesia comes with its share of risk, both to your body and your brain. But, overall, general anaesthesia is very safe: the risks involved in the surgical procedure are usually much higher. But if you have a choice between a local or general anaesthetic, the local does involve far fewer risks.

Read more at Medical News Today

Do you ever worry about general anaesthetic? Were you aware of the risks?



    To make a comment, please register or login
    1st Mar 2018
    The main concern about the risk of getting dementia after having a procedure under general anaesthetic never worries me since, I think, I´m living with dementia since I can remember LOL!!!

    1st Mar 2018
    It's a worry... Any anaesthetists here to respond?
    1st Mar 2018
    Now I have read this article, am beginning to understand some of the inane comments you come up with K-A-L! Just how many times have you been under??

    1st Mar 2018
    How do you explain people who have many operations throughout their lives and survived them with no dementia? There is no concrete evidence that general anaesthetic cause dementia. How do you explain those with dementia who have never had an operation?
    1st Mar 2018
    "According to a study published on, 35 per cent of older patients who had a general anaesthetic actually increased their risk of developing dementia by 35 per cent."
    Third para (above).
    And there may well be no concrete evidence that G.A. doesn't (cause dementia). Explanations for dementia onset otherwise also may not have been included within this particular study.
    1st Mar 2018
    Having an operation without anaesthetic would send you mad instead!
    1st Mar 2018
    Jackie the biggest problem is older people having general anesthetics. It really is a toss up between the pain the individual is enduring and the memory loss from the operation.
    It is an unfortunate side effect.
    1st Mar 2018
    mum had an anaesthetic and I would swear her memory was worse after, ( she has been diagnosed with dementia. she also unbeknown to us went under with high blood pressure ( an issue they knew about ) she came out with very high blood pressure and was discharged the same day ( day surgery) . I dread to think of the risks involved.
    1st Mar 2018
    Maybe these patients were in pre dementia stage anyway & the procedure brought it forward? If an operation is needed this shouldn't make any difference. We live in a world of "what if's"
    1st Mar 2018
    They are working from statistics. My mother filled out an extensive survey before her hip operation and was warned of the possible scenarios before the op.
    If a number of people who have an operation when they are elderly notice a mark changed in brain function post op then the trend leads to the statistical hypothesis.
    The message is really - if your hip is playing up at 65 get it fixed because the risk is so much higher at 80.
    1st Mar 2018
    There is only one question to ask: does the risk of not having the procedure under general anesthetic outweigh the theoretical risk of developing dementia?

    Afterall you may not live to find out if you avoided dementia by not having the GA!
    1st Mar 2018
    There is considerable evidence that after a GA most patients will suffer cognitive changes - short term memory loss, analytic abilities. Recovery is usually very quick but in a few cases may take up to three months. Elderly patients often experience significant short term confusion, behavioural and cognitive changes after GA. It may be from the GA, post-op analgesia, being in a non-familiar environment, pain and stress. It is impossible to determine if GA causes dementia or if it hastens the onset of severe symptoms. Older people should avoid repeated and ‘unnecessary surgery’ - cosmetic etc. On the other hand avoiding surgery perhaps for hip replacement because of the fear of dementia is unwise especially since cognitive decline occurs very quickly if people can’t exercise or remain active. I do wish authors would stop writing these fear-based articles - we all fear the onset of dementia and this constant barrage of articles: GA, alcohol, diet, food stuffs, petrol, etc. In many cases dementia is genetically based and it’s too late to change parents.
    1st Mar 2018
    There is very strong evidence that high excessive levels of alcohol consumption can cause liver damage. I personally know of 2 cases - not known to each other.
    1st Mar 2018
    Yup you are right about alcohol! I probably forgot this one cause I do like a glass of Shiraz. Unfortunately for me alcohol use is related to almost all cancers, heart disease, dementia, diabetes and of course addiction. They don’t know how much alcohol causes all these problems so I am hoping a glass of red every now again is ‘safe’ but who knows.
    1st Mar 2018
    Define 'older patient'. In my early-70s I do not yet feel like an 'older' person. Their must be other risk factors other than simple age, how about general health, obesity, asthma and related conditions. level of fitness as a some items that may influence an individuals reaction to any medical procedure, including anesthesia. This article seems to be another journalistic instance of taking selective parts of a scientific study to try to generate misleading information.
    1st Mar 2018
    If you need surgery get it done now rather than later. If it was that significant they wouldn't operate on the elderly at all.
    1st Mar 2018
    sooo- when I have a colonoscopy, I have an anaesthetic even though it is not considered a "general" what is it then, and has it the same neorological issues as a general?hopefully somebody on the know can answer professionally
    Life experience
    2nd Mar 2018
    For a colonoscopy you would have had sedation. They use the same anaesthetic drugs but in smaller quantities. It is a safer option.
    You are often awake but will not remember talking or being awake. But you will also be asleep but breathing on your own with an oxygen mask on. It’s a safer option for the elderly and can only be used in some procedures. Patients love the relaxed feeling and do not find it scary.
    After the procedure recovery is quick as it was not a general anaesthetic. Patients can go home sooner. And generally not so tired.
    Retiring Well
    3rd Mar 2018
    They put me under anaesthetic for a colonoscopy as It's far more comfortable.

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