President Bush passed his yearly physical on Tuesday, and his doctors say he "remains in excellent health and 'fit for duty.' " According to the medical report, Bush has gained five pounds since last year's exam and lost one-quarter of an inch in height. Wait, is the president shrinking?
Yes, but it's usually a slow process. Men who are around Bush's age—he just turned 60—tend to lose around a tenth of a centimeter in height every year. That's about a twenty-fifth of an inch. According to a study of more than 1,000 adults, the average man starts to shrink at about 30 and will have lost a couple of inches in height by the time he reaches 80.
Several factors can contribute to age-related shrinkage. First, the fluid-filled discs that separate the vertebrae in the spine tend to lose water and flatten out over the years. This pushes the bony parts closer together and makes the torso shorter. (The discs normally make up about one quarter of the length of the spine.) The bony parts themselves can also begin to deteriorate. When they fracture, the spine decreases in length. Women are more vulnerable to this kind of bone deterioration, called osteoporosis, than men. That's why women tend to shrink more rapidly.
Bone deterioration can also increase the natural curvature in the spine, causing a hunched posture. The hip and knee joints may also shrink as they lose fluid and the cartilage wears away. (Good news for seniors: Recent research suggests that your brains and bladders may retain their normal size.)
What about Bush? If we're to believe this year's numbers, he's shrinking at a rate of one inch per presidential term—more than five times the average rate for a man of his age. You might expect very rapid shrinkage if Bush were a giant, since beanpoles tend to lose height faster than little guys. But our commander in chief isn't even 6 feet tall. The Explainer hoped that doctors at the National Naval Medical Center could account for this distressing statistic, but hospital officials deferred all shrinkage questions to the White House press office. The White House did not respond to repeated inquiries.
We can only speculate that the apparent shrinkage is the result of a measurement error. The quarter-inch decrement this year might represent a fudged reading of a normal, age-related height loss. Or it could be that the doctors measured Bush at different times of the day. A person tends to be taller first thing in the morning, when their intervertebral discs are fluffed up from a night of sleep. As you walk around over the course of the day, gravity flattens your discs—which makes you a little bit shorter by bedtime.
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Explainer thanks Shreyasee Amin of the Mayo Clinic.