July 12th, 2010
04:42 PM ET

Bigger brain may mean less Alzheimer's risk

Having a big brain is not just fodder for bragging about how smart you are. According to a new study, it may also mean less chance of developing Alzheimer's disease symptoms later in life.

The research, published today in the journal Neurology, found that among patients with Alzheimer's disease symptoms, those who had larger brains did better on cognitive tests - meaning their memory, and their ability to think and understand, was better.

"At the same level of brain atrophy or brain damage, patients with larger heads have better cognitive performance, so they somehow offset those symptoms related to brain damage," said Dr. Robert Perneczky, lead study author and a psychiatrist at the Technical University of Munich in Germany.

Researchers administered cognitive tests and brain scans to 270 patients with symptoms of Alzheimer's disease. The patients' head circumference was measured (as a proxy for brain size, since big heads tend to house big brains) and compared the severity of the brain damage with the scores on cognitive tests.

The fascinating finding - if you were to compare two brains with the same level of nerve cell death, the same level of damage, the same amount of missing brain matter - the person with the big brain would win out in the cognitive testing.

The key may be something called brain reserve, the brain's ability to compensate for brain damage. People with larger heads - and hence larger brains - most likely have more of it. "More brain reserve means that an individual can cope better with nerve cell loss as in with Alzheimer's disease," said Perneczky.

It may be that a larger brain has more matter to give, so that the loss of nerves and synapses (those trusty conveyors of information and memories) is not as potent. Another theory is that that surplus brain tissue may allow the brain to find alternative routes for information by laying down new pathways and networks for information.

All of this is great news for folks who are blessed with genetically big brains, but is there hope for the rest of us? Turns out that the key to having a big brain starts with how you develop during early childhood.

"Our results...underline the importance of optimal neurologic development in early life," said study authors. "Brain size reaches 93 percent of its final size at age 6, and therefore measurements of head circumference mainly reflect brain growth during the first few years."

That means not just genetics, but how we nurture a developing child's brain development, could have implications in the twilight of life when cognitive decline sets in. Proper nutrition and more obvious brain-stimulating activities like cuddling, playing with, and talking to your child are high on the list. (Click here for a guide to healthy child brain development from the Centers for Disease Control and Prevention).

Where does that leave those of us over the age of 6? Experts believe that living an active lifestyle may help to fend off Alzheimer's disease. That means eating a healthy diet, exercising, keeping up a healthy social life and doing "brain exercises" like reading and doing crossword puzzles.

soundoff (39 Responses)
  1. Jolat

    Bigger brain may mean less Alzheimer's risk

    This is great news!!!!
    I will NEVER get alzheimer's!!

    July 12, 2010 at 17:31 | Report abuse | Reply
    • david

      why? No brain no alzheimer's?

      July 12, 2010 at 19:39 | Report abuse |
  2. Csh

    Jolat – over-inflated ego has nothing to do with brain size – sorry ! 😉

    July 12, 2010 at 17:50 | Report abuse | Reply
  3. Kraznodar

    What ever happened to the research where they extracted the brain plaque from Alzheimer's sufferers and injected it elsewhere in the body and saw the body then clear the brain of the plaque as the immune system kicked in?

    July 12, 2010 at 17:51 | Report abuse | Reply
    • E. W. Parks

      There are no such experiments. They would require permission of the subject, for one thing, and the subject would not likely be in a state in which he or she could give informed consent. Most importantly, one cannot simply go into the human brain and remove parts of it without further damaging the brain's ability to function (the 'plaques' are embedded in the brain tissue). This would be an odd way to try to restore cognitive function to an already weakened brain. Moreover, 'plaque' is not the only 'cause' of Alzheimer's (whose cause isn't really known); there are also 'tangles' and other malformations of the brain, and other phenomena whose causes, in turn, are unknown.

      Advanced Alzheimer's is seldom the only cause of dementia. It coexists with vascular dementia, Lewy Body disease, and other irreversible conditions.

      July 12, 2010 at 18:37 | Report abuse |

    good gracious...i have big head .. i am so happy today....less chance for alzheimers...yipeee !!!

    July 12, 2010 at 17:51 | Report abuse | Reply
    • Darth Vader

      Yes, but if it's filled with helium, it won't help!

      July 12, 2010 at 18:34 | Report abuse |
  5. Scott Lilienfeld, Emory University

    Haven't read the original article, but based on the CNN description the headline ("Bigger brain may mean less Alzheimer's risk") appears to be grossly misleading. The study described says that given the presence of Alzheimer's symptoms, afflicted individuals who happen to have larger brains do better on cognitive tests. It does not say that people with larger brains are less likely to develop Alzheimer's disease – only that they are less likely to suffer severe cognitive symptoms as a result of Alzheimer's, presumably because they have more cognitive reserve to begin with. This is a crucial distinction. The headline confuses a conditional probability (which is what the study described reports) with a probability. Either the study description is wrong, the headline is wrong (or at least very poorly written by the story editor), or both. CNNHealth should clarify.

    July 12, 2010 at 18:05 | Report abuse | Reply
    • E. W. Parks

      Scott is absolutely right. Even if it turns out to be true that having larger than normal brains delays some loss of cognitive function, Alzheimer's is a progressive disease. In short, you can run but you can't hide.

      July 12, 2010 at 18:43 | Report abuse |
    • Brian

      I"ve an avid reader of CNN but lately their headlines are getting ridiculous. Is there no staff editor anymore?

      July 12, 2010 at 19:17 | Report abuse |
    • Wzrd1

      All too true. These days, it seems that CNN began staffing their ranks from the local center for the mentally challenged.
      A delay in end state disease is far from remarkable. Though it DOES suggest some OTHER studies regarding larger brains and additional redundancy in circuit formation regarding injuries...
      But, at the end of the day, it does very little toward understanding the disease or treating it. Only a guess at a longer life span with someone with a larger brain.
      In short, a waste of resources and money that could have been better spent.
      But, the good Doctor Gupta seems to be fascinated with pseudo science these days.

      July 12, 2010 at 21:36 | Report abuse |
    • Pete

      I saw once on TV that London taxi drivers have bigger brains on average. Maybe they could investigate whether the incidence of Alzheimer's is lower among London taxi drivers than average, if there are enough of them to test.

      July 13, 2010 at 08:36 | Report abuse |
    • Elder Depot

      While I completely agree I don't think that you can point the finger solely at CNN here. I've put together a list of Dementia Prevention "Mays" for a blog post and every news agency had extremely misleading headlines – and often articles. The BBC was the least biased but even they played the story up. Its very disappointing.

      Sigh. Professional news is becoming more and more about entertainment. I miss the days of Walter Cronkite.

      July 13, 2010 at 17:15 | Report abuse |
  6. ohgreatanotherwaytonotmeasure up

    Great. I am a medium sized man. Now I am inferior to larger men not only in size, but also in this way. And only recently it was confirmed that taller men with strong jawline were more successful and more desirable to women. Why don't all us medium and small sized guys just end it all right now? All the recent findings point out that we aren't as desirable "specimens" as larger men.

    July 12, 2010 at 18:13 | Report abuse | Reply
    • Elder Depot

      Actually, research has shown that larger men are more susceptible to heart problems so that's one area where you have a solid advantage.

      July 13, 2010 at 17:17 | Report abuse |
  7. me

    so Einstein would have had Alzheimers

    July 12, 2010 at 18:25 | Report abuse | Reply
  8. jstmyview

    That's really bad news for "Republicans" and "Tea Baggers".

    July 12, 2010 at 18:27 | Report abuse | Reply
  9. Darth Vader

    The ability to destroy a planet is insignificant when compared to the power of the force.

    July 12, 2010 at 18:36 | Report abuse | Reply
  10. Mark C

    Well i'm glad this pumpkin head of mine is good for something.

    July 12, 2010 at 18:37 | Report abuse | Reply
  11. Jerry


    Yes, it is. It means the Democrats will lose their minds before they find their sanity and become Republicans.

    July 12, 2010 at 18:56 | Report abuse | Reply
    • Bob

      and the only President to suffer from this???? I don't believe he was a Democrat.....

      July 12, 2010 at 22:37 | Report abuse |
  12. Mike

    I'm extremely suspicious of the claim that anything you do for your child in early childhood results in them having larger brains. It may increase their intelligence and neural development, but is there any evidence that that cuddling or talking to your child results in them having a physically larger head? I'm not saying that it's certainly untrue, but it seems more likely to me that skull size is a result of genetics, not environment. Link to a study for this claim please!

    July 12, 2010 at 19:02 | Report abuse | Reply
    • fontanel

      I think it has to do with fontanel and the brain size increase during first 2 years of the child head before it is becoming ossification. It is not possible to increase the size of the head when the bone ossify after age of 2. I wonder how the brain can increases even more between age of 2 and 6.

      July 13, 2010 at 01:56 | Report abuse |

    HAH! I'd get that insult all my life: "You're Big Headed, Big headed, Big.. wait...do you mean big "Brain?"
    Nevermind(one of my very rare mistakes).

    July 12, 2010 at 19:35 | Report abuse | Reply
  14. Jennifer

    Wow! Hats never fit my big head. This has disturbed me. However, this is a good consolation.

    July 12, 2010 at 20:05 | Report abuse | Reply
  15. rh

    My middle son has an autistic like disorder, and when he first visited a developmental neurologist, the neurologist was concerned that his head was 95th percentile but his height and weight were only 75th percentile. Both parents were there and the nurse said "hmm, maybe I'll see if you guys have large heads" and bingo 97th and 98th percentile. They ruled out macrocephaly as being related to his autism but thought it might be.

    One thing I have heard is that lack of stimulation (boredom) kills brain cells, so I wonder if it leads to Alzheimer's. I know people who seem fine before they retire but have Alzheimer's within a year of losing daily contact with people.

    July 12, 2010 at 20:44 | Report abuse | Reply

      Good-upside of daily dealings with people, I suppose. I suffer onward.

      July 12, 2010 at 20:51 | Report abuse |
    • Nursehope

      Rubbish. Lack of mental stimulation does not cause neuronal death, Your propensity for repeating urban legend astounds me. Retirement does not predispose ANYONE to AD. Why would you even repeat such nonsense?

      July 12, 2010 at 22:54 | Report abuse |
  16. Fran

    I wish CNN would stop trying to scare us to death with articles about Alzheimer's Disease in the news almost everyday. The public is well aware of the symptoms of the disease. So are our doctors. As of right now, there is no way to prevent the disease. So give it a rest. A BIG one. All we're interested in now is the news of a cure or an arrest in the progress of the disease. There are much more important things to be concerned about RIGHT NOW - BP's oil spill, bringing our warriors home from Iraq and Afghanistan, this world-wide recession, putting our people back to work. [I DO NOT CARE ABOUT LINDSEY WHATEVER-HER-NAME-IS. You insult the intelligence of the American public.] So help me, the older I get, the less respect I have for CNN.

    July 12, 2010 at 21:54 | Report abuse | Reply
  17. Iloveturtles

    Uhh.. this study was already done in 2003. Good job spending thousands on what was already discovered 7 years ago. You know how many cheap hookers I could have bought with that kind of money??

    July 12, 2010 at 22:01 | Report abuse | Reply
  18. Iloveturtles

    "What we found was very clear,' said the group's leader, Dr Christopher Martyn, of Southampton University's environmental epidemiology unit. 'The larger a person's head, the less likely their cognitive abilities are to decline in later years.'


    July 12, 2010 at 22:03 | Report abuse | Reply
  19. Manny

    Which one is the bigger brain? Is it the one on the left or the right? and if one is bigger than the other, how much bigger is it?

    July 12, 2010 at 22:30 | Report abuse | Reply
  20. Kevin

    Bad news for my brother's wife.

    July 13, 2010 at 00:11 | Report abuse | Reply
  21. Pumpkin Headed Bob

    When I was on active duty in Korea I could wear my helmet without its liner (almost), so does that mean I'll meet my maker without any risk of Alzheimer's disease?

    July 13, 2010 at 00:33 | Report abuse | Reply
  22. LLL10

    This seems like an odd study, but I suppose it is consistent with all the hype surrounding neurogenesis and neural plasticity. Behavioral neuroscientists who study these phenomena often find that tons of environmental factors can increase neurogenesis, but not all those new neurons survive and integrate into the brain circuitry. Can the surviving neurons become a part of this "brain reserve" and protect people from Dementia/AD? If so, crossword puzzles might be beneficial.

    On the other hand, having a bigger brain is not always beneficial. Bigger brains might protect people from AD but make them more susceptible to brain tumors. Think about it!!

    July 13, 2010 at 07:17 | Report abuse | Reply
  23. Richard Pressinger

    Here's something interesting – People with Alzheimers have a weaker functioning Blood Brain Barrier (the blood brain barrier blocks harmful substances from entering the brain cell network – see blood brain barrier in Wikepedia for documentation). How does the blood brain barrier become damaged? So far about a dozen studies have shown the blood brain barrier gradually melts away from – 1) very low levels of mercury – 2) lead – 3) monosodium-glutamate – 4) microwave frequencies – 5) the pesticide ingredient MCPA – and 6) chlorinated sugars. Hmmm... Combining these two facts leads to some interesting theories about why Alzheimers has increased over the past 50 years.

    July 13, 2010 at 20:54 | Report abuse | Reply
  24. Shiki

    Thank god for my giant brain.

    July 14, 2010 at 09:22 | Report abuse | Reply
  25. arthur prince

    Mine is tiny, will I get a little Alzheimer?

    July 15, 2010 at 00:02 | Report abuse | Reply
  26. Steve in AZ

    Gosh, how interesting. Based on the faulty logic of this article, people with larger heads must ingest more curry (known to inhibit Alzheimer's onset), have lower blood pressure, lower LDL cholesterol levels (correlates to later Alzheimer's onset), earn more college degrees, physically exercise to stimulate brain plasticity and neural circuit development, solve more crossword puzzles, consume greater amounts of fish oil, anti-inflamatories, anti-oxidants, and experience fewer head trauma incidents throughout life (brain trauma correlates to Alzheimer's onset). In addition they drink less alcohol, and do fewer illicit drugs than those people who have smaller craniums. How fascinating....What's most amusing is that the indication of a larger cranium implies greater cognitive ability accross the board. It's the ratio of brain size to body size that matters (body fat percentage aside). The notion that surplus brain tissue allows for greater capacity to preserve cognitive abilities is laughable. Alzheimer's tends to progress at variable rates from about 4 to 15 years. A neuron in a smaller brain can have significantly more dendrites than one in a large brain. Since when is surplus brain tissue off-limits to beta amyloid plaques? In Alzheimer's, where brain tissue exists, beta amyloid plaque will eventually exist. With 50% of 80 year olds showing symptoms of Alzheimer's, the variable of cranium circumference is miniscule, and the motive to study such trivial aspects of such a widespread and devastating disease implies that these researchers must be suffering from some form of dementia themselves.

    July 15, 2010 at 04:39 | Report abuse | Reply

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