January 13, 2014
By Robert H. Shmerling M.D.
Beth Israel Deaconess Medical Center
Ever wonder what makes babies so cute? Maybe it's those wide, innocent eyes. I think it's their huge heads. It's a feature that makes babies (and other immature animals) look, well, immature...and adorable.
If you're an adult, the length of your head is about 1/8 of your total height. As a newborn, your head was much bigger relative to your body: It was about 1/4 of your total height.
In fact, one of the first tasks of infancy is getting control of that big head. Neck muscles quickly develop to balance the relatively large and heavy skull and brain atop the body without flopping off to one side. You can actually guess an infant's age fairly well just by seeing whether he or she has mastered head control. By the age of 3 to 4 months, most babies are there.
Besides contributing to the undeniable cuteness of infants, the head is the source of many myths and misunderstandings. Read on to learn more about this amazing structure.
Can You Really Shrink a Head?
The answer to this age-old question is yes. (I'm not so sure I'm glad to know the answer to this.)
Headhunters would shrink and display heads as a trophy. It was a sort of primitive gloating about whom you've vanquished. True head shrinking requires weeks of "processing." While it's probably best that I not go into the details, it involves severing a human head, removal of the skull and a fair amount of boiling.
Back to top
Do You Lose Brain Cells as You Age?
Researchers have made a number of observations regarding the size of the human brain:
- The head "shrinks" proportionately, as described above, from infancy to adulthood.
- Brain volume (one measure of its size) slowly decreases starting in early adulthood; the process accelerates around age 60 and is particularly rapid among those with Alzheimer's disease.
- The notion that intelligence wanes with age is a myth. However, as with many myths, there is some element of truth to it: Certain types of cognitive function tend to decline with age. Examples include the ability to incorporate and react quickly to new information, formation of new memories and multi-tasking. However, knowledge from past learning, remote memory and verbal agility tend to be well preserved as we age.
- Treating risk factors for conditions that can impair brain function may prevent declines in cognitive function. For example, the risk of stroke-related dementia decreases when high blood pressure is well treated.
What about mentally stimulating activities, such as board games or crossword puzzles? Don't they keep the mind fit?
There is a considerable amount of research linking social ties, stress reduction and mental exercise with a lower incidence of dementia and cognitive decline. The problem is that these "associations" do not mean that these factors are actually causing better mental function. But, stand by. The aging brain turns out to be much more flexible than previously thought. We may someday learn that a combination of factors and behaviors can actually protect the brain's function over time.
Interestingly, physical exercise may be even better for the brain than mental exercise. A study in 2006 found increased brain volume and blood flow to the hippocampus (a part of the brain involved in memory) among those who participated in aerobic exercise. In the lab, new brain cells appeared in the brains of exercising mice. And a 2010 study linked walking at least 6 to 9 miles per week with a lower rate of age-related brain shrinkage and a lower risk of memory problems or dementia.
My own view is that it can't hurt to challenge your mind and keep it busy. And physical exercise has so many health benefits, it's hard not to recommend it. But I don't think anyone should rely heavily on these to maintain mental sharpness.
Back to top
Does Drinking Alcohol Shrink the Brain?
Perhaps you've heard that you lose brain cells every time you drink.
It's another myth. It's true that people who abuse alcohol have a higher rate of brain disease. But, it's not clear that alcohol is the direct cause. It may be a combination of head trauma suffered by alcoholics, nutritional deficiencies, or, perhaps, a toxic effect of alcohol on the brain.
The good news is that moderate alcohol use does not seem to be harmful to the brain. In fact, it may be helpful. For example, a 2011 study found that moderate alcohol intake (about 2 alcoholic beverages per day) was associated with a significant reduction in dementia compared to non-drinkers.
Back to top
Why Are Psychiatrists Called "Shrinks?"
It's probably related to the notion that psychiatrists are "meddling" with your brain. The term is a relatively recent addition to our slang vocabulary, as its use has been dated to only the late 1960s. By most accounts, "shrink" is a term combining both endearment and derision, putting psychiatry on par with primitive (and hostile) tribal ritual. But it's also used by people who endorse the benefits of psychiatric care.
Back to top
The Bottom Line
Most of us don't think much about whether our head size is changing. I think that's all for the best. After all, it's not clear you can alter your brain size. And if you can, it's by activities and lifestyle changes that would be recommended even if it had no effect on brain function.
So, keep your brain and body active, stay socially connected and avoid those things that put the brain at risk (such as excess alcohol intake). And, if you have significant psychological distress or mental illness, see a shrink. But don't worry that your head will actually shrink. Yes, it can happen; hopefully, it will never happen to you.
Back to top
Robert H. Shmerling, M.D., is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.