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Obesity linked to brain shrinkage, erectile dysfunction

August 25, 2009 | 12:11 pm

The L.A. Times' science and health staff has recently been accused of an ongoing campaign against fat people. Commenting on a post Monday, reader Big Jim Slade predicted "tomorrow we'll have another fat assault on how breathing the same air as fat people is dangerous...Maybe we should waterboard them, eh?"

Don't shoot us, Big Jim: We're just the messengers!

But for those of you who share Big Jim's sense of persecution, let me say, I feel your pain. If you think it's hard reading our drumbeat of reporting on the health effects of obesity, imagine what it's like for, say, a significantly overweight health reporter to write this stuff on a daily basis. (Trust me, I'd rather be at the gym--though a controversial recent report suggests that won't help me lose any weight either.)

Which brings me to the latest crop of bad news on being obese--and there is just no way to sugarcoat this pair of studies, my friends: being fat makes your brain shrink and, if you are a man, your penis limp.

A new brain-imaging study by researchers at UCLA and the University of Pittsburgh finds that the brains of overweight and obese subjects were on average 4% and 8% smaller, respectively, than the brains of those who were at a healthy weight--evidence, according to UCLA neurology professor and study author Paul Thompson, of "severe brain degeneration."

For the obese--those with a BMI over 30--the news is particularly bad: the areas of significant observed shrinkage were the frontal temporal lobes, the seat of higher-order reasoning and judgment; the anterior cingulate gyrus, key to attention and decision-making as well; the hippocampus, where long-term memories are processed, and the basal ganglia, from which smooth movement is initiated.

Overweight people--those with a BMI over 25--also had shrinkage in the basal ganglia, as well as in the parietal lobe, where we integrate sensory input and position ourselves in space, and in the brain's white matter, which helps speed messages among regions of the brain that must work together for us to function properly.

After virtually weighing and measuring the brains of 94 subjects over age 70, the study authors concluded that the brains of the overweight appeared, on average, eight years older than those of subjects at healthy weight. Brains of the obese appeared 16 years older. While the subjects scanned in the study showed no outward signs of cognitive impairment at the time of the study, the study's authors predicted the premature aging and loss of brain volume they observed would put heavier subjects at greater risk of Alzheimer's disease and other degenerative brain diseases.

Why? Because a big, robust brain under attack by these diseases can often compensate for their ravages for some time--forestalling the onset of symptoms. But a shrunken brain is not so resilient. Memory loss, movement problems and cognitive deficits are far more likely to show up early for overweight and obese patients. This study is published online in the journal Human Brain Mapping.

The current issue of the "journalzine" Obesity and Weight Management--free online this month-- explores another, better-known fellow-traveler of obesity: erectile dysfunction. Erectile dysfunction is a common side effect of high blood pressure and atherosclerosis. Those conditions can lead to blockage of the major arteries that lead to the brain and the heart, causing stroke and heart attack, respectively. But they also can lead to "microvascular disease," including erectile dysfunction, say University of Colorado physician Adam Gilden Tsai and the University of Pittsburgh's Adam Sarwer.

Tsai and Sarwer present the case study of a 48-year-old man whose BMI is 32.6--considered "mildly obese," with erectile dysfunction that is not relieved by the use of tadalafil, the erectile dysfunction medication better known as Cialis.

There is, at least, some good news: A study expected to be published next month in the Lancet by the UCLA-Pitt researchers that observed brain shrinkage is expected to suggest that physical exercise can help spare even the obese some of the consequences of their excess weight. And, the patient with erectile dysfunction was medicated for his high blood pressure and, after dietary counseling, lost 4.6% of his body weight--just under 10 pounds. "The patient has been able to achieve adequate erections with the use of ED medication as needed," the authors report.

Now that's a happy ending.

-- Melissa Healy

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