Maclean's Interview: neurologist Martin Samuels

Brain and aging, supplements, special diets, and why old people know more than young people

Aging, Brain, Neurology

Photographs by Jodi Hilton/Getty Images

Dr. Martin Samuels heads the Harvard Medical School Department of Neurology at Brigham and Women’s Hospital in Boston, where he is also neurologist-in-chief, and has received dozens of international honours, including numerous teaching awards. On April 15, he will deliver the inaugural lecture of the Scienta Health Series in Toronto. His topic is “Successful aging: important advances in protecting your brain.”

Q: What are the big controversies in neurology regarding cognitive impairment associated with aging?
A: There are thousands. One is that nobody really knows the causes of Alzheimer’s disease. One hypothesis, invented by a colleague of mine, is that something called the amyloid precursor protein is the cause. Most people think he’s right, but a strong minority think it’s something completely different. A second controversy concerns treatment of Alzheimer’s. The FDA has approved four drugs that act indirectly, on memory systems, and some people think they should be used freely, while others question the benefit-to-cost ratio. Double-blind studies show that families can’t even tell whether the patient is taking the drugs or not, but families still want whatever is available. The question becomes whether it’s worth it, given the high cost and the side effects, like making people nauseated.

Q: Is memory loss inevitable?
A: An aspect of memory is lost, predictably, with aging: it becomes more difficult to think of the names of things and people. If you give people the Boston naming test—a standardized test of 60 objects that starts with easy words like “house” and ends with low frequency words like “protractor”—and you force them to go fast, you can predict age quite accurately. A normal 30-year-old would get over 57 correct, a normal 60-year-old would be more like 50 out of 60, and a 90-year-old, more like 40 correct. If you have Alzheimer’s disease, or a stroke that interferes with language in a pathological way, you might get only 10 right.

Q: Why does word retrieval diminish with age?
A: Neurons are dying; the brain is actually shrinking. If you took a perfectly normal 90-year-old who everybody in the family says is sharp as a tack, even if he was still the president of IBM, his brain would be lighter than it was when he was 80, and so on, all the way back to the peak weight of the brain, which is around 17 or 18 years old.

Q: Does intelligence protect against cognitive decline because you have a larger cognitive reserve?
A: It’s very hard to measure cognitive reserve. You hear stuff like “Einstein used just 38 per cent of his brain,” but there’s no evidence that’s the case. As far as we know, we are all using all of our brain, the neurons are firing and making electrical connections. What makes for fast cognition—intelligence, quick thinking—is the microscopic complexity of the network. It’s like a radio: it’s about the number of wires and the number of connections and, of course, they have to be connected correctly to work. The evidence we have is that if you start with very high cognition it doesn’t mean you’re less likely to get Alzheimer’s, but it does mean it takes more brain loss before it becomes obvious to the outside world that anything’s wrong.

Q: Is there any good news about our brains and aging?
A: Oh yes. Given the same basic intelligence, old people know way more than young people. They’ve forgotten more because they’ve lived so much longer, but what’s left is probably an order of magnitude greater than what a young person has, even though young people know things that some old people don’t, like how to text on a cellphone. It’s important to realize that forgetting is fine, in fact it’s critical for normal brain function. There are very good rememberers, idiot savants, who can tell you whether the 20th of April 1908 was a Wednesday, but they can’t do anything creative or that requires new thoughts because every circuit is completely jammed with useless old data.

Q: What can we do to protect our brains as we age?
A: There are no magical pills, vitamins or tricks which prevent aging. Aging cannot be prevented. But what one can do is make the environment for the nervous system as amenable as possible, so that as it ages, it can still function at a pretty high level, and cognition can be maintained well into late life, provided there isn’t a disease. More than anything else, there are things to avoid: smoking cigarettes, which is bad for the brain’s blood vessels, and getting morbidly obese and getting Type 2 diabetes, which is bad for your blood vessels, heart and your kidneys—when those don’t work, the brain doesn’t work well either. Very high levels of bad cholesterol: not good. Very low good cholesterol: also probably not good. A lot of alcohol—not one or two drinks a day, but a lot—is probably bad. And there’s the potential that there are toxins in a lot of herbs and spices that are sold as anti-aging cures. You don’t know what’s in them or how they’re made, because they’re not regulated by the FDA or the corresponding agency in other countries. A lot of these anti-aging teas, for instance, actually have neurotoxins in them.

Q: That’s it?
A: There are a few tricks, too. Tricks don’t prevent disease, and if you get a brain tumour or Alzheimer’s, tricks don’t work, but a good one is to sleep. Sleep is a very important part of memory consolidation—many of us believe that’s its function—and if you don’t sleep well, you put an extra stress on your aging nervous system.

Q: How much is enough?
A: I don’t think it matters exactly how much. One of the key things about sleeping is not to obsess about it, just do the right things. Don’t take stimulants—caffeine, diet pills, or things that contain caffeine, like chocolate— or exercise within a few hours of bedtime. You want an hour of downtime if possible before going to bed, and it’s good to dim the lights; it has a direct effect on the pineal gland, which secretes melatonin, a pro-sleeping hormone.

Q: As you get older, isn’t it harder to sleep?
A: Many reasons people don’t sleep well have nothing to do with aging. Drinking is the biggest problem, I would say. People think a drink will help them fall asleep, and it does, but as the alcohol level in the blood falls, they wake up two or three hours after going to bed. You shouldn’t drink significantly—a small glass doesn’t bother some people—within a couple of hours of going to bed. It’s very disruptive to sleep.

Q: We keep hearing about sudoku, ballroom dancing—don’t any of those things help our brains?
A: Well, ballroom dancing isn’t bad, it combines exercise and socialization. Physical exercise is associated with a lower risk of Alzheimer’s disease, and to the extent that Alzheimer’s is an analogy for normal aging—which isn’t necessarily true—that’s a reasonable thing to do. People should exercise about 20 minutes, if they can, at least five times a week. It’s the one thing that really works but we don’t know why.

Q: What about those brain games on the computer—just marketing scams?
A: “Scam” is a little strong, but they’re marketing efforts, no question about it. The basis is a famous study of nuns who did crossword puzzles and had a low incidence of Alzheimer’s disease. The problem with the study, and subsequent studies, is that there’s a pre-selection bias: if you’re a person who does crossword puzzles and you’re still doing them when you’re 90, you probably have a genetic background of high cognitive skills, so even if you get Alzheimer’s disease, it’s going to take longer before anybody notices. There’s no evidence that doing the New York Times crossword puzzle prevents Alzheimer’s.

Q: What do you personally do to protect your brain?
A: Nothing.

Q: Not even exercise?
A: Well, my wife and I run every morning, 1.5 to 2 miles—no more because I don’t want to wreck my knees—but that’s for general well-being. It’s more a psychological thing.

Q: You don’t take vitamins or supplements?
A: No. Dietary supplements are just a waste of money.

Q: What about this claim that omega-3 maintains the flexibility of the cell wall of the neuron?
A: What you can show about a cell wall in a lab doesn’t necessarily have any effect on the physiological system in vivo. There’s no benefit for omega-3 with regard to maintaining cognition or treating Alzheimer’s.

Q: What about a special diet?
A: I don’t believe in that at all. I personally enjoy everything and encourage my patients to do the same. Eating is one of the great pleasures of life. I’ve seen way, way more problems in people who’ve gone on diets or decided to take megavitamins than in people who have a normal diet.

Q: What kinds of problems?
A: There are all sorts of neurological complications of different vitamins. I had a man recently who decided he was going to take zinc, which is advertised in health food stores as being good for your memory and your libido. What he didn’t know is that zinc induces a protein in the gut which causes a loss of copper. He became very weak in the legs, numb and unable to walk, basically, and people thought he had a spinal cord tumour or some other horrible thing. But all it was was a profound copper deficiency.

Q: Why, if they don’t work, do the media keep telling us about vitamins and other things “proven” to enhance cognitive functioning?
A: Over the years, journalists have interviewed me about one thing or another, and they always want to put in their article what somebody or other can do about a problem. It’s the obsession of advanced societies: having too much confidence in technology, to the point where people believe everything can be prevented if you just do the right things. Well, there isn’t always something to do.

Q: When you were in med school, was anti-aging even a focus in neurology?
A: I finished medical school in ’71, and there was no talk about neuroprotection or anything of the kind. It’s become a focus because of the public’s interest in it, primarily. Successful aging is an aspect of neurological medicine that I would say is analogous to cosmetic dermatology: it’s nice to have, but it isn’t really the important thing. Neurology is a medical field, and what we’re really worried about are the diseases that can disable or kill you: brain tumours, strokes, epilepsy. Normal aging is not a disease, even though people who are 90 walk slower and their memory is not what it once was, and neither are their joints, or their faces. Successful aging is [a concept] that has come along in societies where people have a lot of resources and leisure time. In Africa, where people are falling down on the street and dying of brain infections caused by parasites, they don’t worry about successful cognitive aging. It’s a luxury.

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