The New York Times - 30.07.2019

D4 N THE NEW YORK TIMES, TUESDAY, JULY 30, 2019

Among men who are
at high risk for H.I.V.
infection, only about
one in three is taking
a drug to prevent transmission
of the virus, according to a sur-

vey from the Centers for Disease
Control and Prevention. The
drug, Truvada, is taken daily as

part of a preventive strategy
called pre-exposure prophylaxis,
or PrEP.

For the report, published in
MMWR, C.D.C. researchers
studied 7,873 high-risk men from

20 American cities who were
negative for H.I.V. and com-
pleted a behavioral survey in
2014 or 2017. Those considered at

high risk either had a partner
who was H.I.V. positive or had at
least two male sex partners in

the past year, and they reported
having anal sex without a con-
dom or a sexually transmitted

infection — syphilis, gonorrhea

or chlamydia — in the past year.

Among the men in the survey,

PrEP use rose steeply from 2014

to 2017, from 6 percent to 35

percent. But PrEP use varied by

race, with 42 percent of high-risk

white men taking the drug, 30

percent of Hispanic men and 26

percent of black men.

Other reports have found

lower rates of PrEP use, with

about 270,000 of the estimated

one million Americans at high

risk taking the drug.

In February, the Department

of Health and Human Services

announced a plan to end the

H.I.V. epidemic in the United

States, with use of PrEP a cor-

nerstone of the initiative.

“Higher coverage is needed,

especially among black and

Hispanic men who have sex with

men, to end the H.I.V. epidemic

in the United States by 2030,” the

researchers concluded.

DRUGS

Underused Tool to Fight H.I.V.

In Brief TOBY BILANOW

Does eating smoked fish,

such as smoked salmon

or whitefish, increase the

risk of colorectal cancer

or other cancers, the way

processed and deli meats

do?

It might. From a cancer risk
perspective, the American Insti-
tute for Cancer Research consid-
ers smoked and cured fish in the
same category as processed

meats. Other cancer research
groups are less clear on whether
eating smoked and cured fish
carries the same risks as eating
processed meats.
In 2015, a working group of the
World Health Organization’s
International Agency for Re-
search on Cancer classified
processed meat as a carcinogen,

saying there was sufficient evi-
dence that it causes colorectal
cancer. This was a big deal,
because very rarely do scientists
use the word “cause” when it
comes to food and disease. The
researchers who reviewed the

evidence, however, did not look
specifically at smoked or cured

fish in their evaluation. For now,
according to a spokeswoman
from the I.A.R.C., their answer to
the question of whether eating
smoked or cured fish affects
cancer risk is, “We don’t know.”
“Processed meat” refers to

meats that have been treated
through techniques that boost
flavor and preservation, such as
curing, fermenting, salting and
smoking. The category includes
hot dogs, ham, bacon, sausage,

jerky, pepperoni, deli meats
(such as bologna, smoked turkey
and salami) and any sauces
made with these products (such
as pork sausage ragù or bacon
salad dressing).
The WHO announcement also

classified red meat — meat from
mammals, such as beef, pork,
lamb and goat — as “probably
carcinogenic,” citing possible
links to pancreatic and prostate
cancers in addition to colorectal
cancer.

“Even though it’s possible that
processed fish and even chicken
and turkey could be better alter-
natives” than processed red
meats, which carry additional
potential health concerns, “for

now we have to look at all of it as
processed meat,” said Alice
Bender, the senior director of
nutrition programs at the
A.I.C.R. “We can’t say that one is
better than the other.”
Ms. Bender, a registered dieti-

tian, suggests limiting consump-
tion of smoked and cured fish,

enjoying it as an occasional treat

versus eating it every day, for

the same reasons that you

should limit processed meats.

She notes that the processing

itself appears to be the underly-

ing issue when it comes to can-

cer risk. As with meat products,

salmon and other types of fish

are often smoked or cured to

enhance flavor and preservation.

Lox, for instance, is salt-cured,

or brined. Cold-smoked salmon

is also brined but then smoked at

a very low temperature.

It is unclear why processing

may pose a cancer risk, though

salting could be one factor. The

World Cancer Research Fund,

for example, states on its website

that there is strong evidence that

preserving foods through salting,

“including pickled vegetables

and salted or dried fish,” in-

creases the risk of stomach

cancer. Cantonese-style salted

fish, a popular item in Southern

China that is both salted and

fermented, has also been tied to

an increased risk of nasopharyn-

geal cancer.

Other processing methods

may also play a role. The high

temperatures used in some

smoking techniques could be a

risk factor, as high heat has been

linked to formation of cancerous

substances when cooking meat.

So could the nitrates used as

preservatives. Or, it could be a

combination of factors.

Although the A.I.C.R. advises

against eating too much smoked

or cured fish, other leading can-

cer research organizations do

not yet draw a firm conclusion

one way or another.

One reason for the uncertainty

is that Americans tend to eat far

less lox, smoked trout, smoked

whitefish and the like compared

to how much bacon, deli meat

and sausage they consume.

Because smoked fish is not a

central part of the typical Ameri-

can diet, not enough data is

available for a statistically mean-

ingful statement about the rela-

tionship between smoked fish

and cancer risk, according to a

spokeswoman from the National

Cancer Institute.

Fish has also been associated

with numerous positivehealth

outcomes and may lower the risk

of heart disease and even some

cancers, especially when eaten

instead of red meat. As to

whether the potential benefit

from consuming smoked or

cured fish might in essence

cancel out the potential harm

from the processing, more re-

search is needed.

Smoking and curing give foods

flavor that makes them appeal-

ing, as well as shelf life that

makes them convenient and

more affordable, so another

important question yet to be

answered is whether the cancer

risks of not getting enough fish

in the diet might outweigh the

cancer risks of eating fish in

smoked or cured forms.

SOPHIE EGAN

Ask Well

ERICA YOON FOR THE NEW YORK TIMES

We l l

WEIGHT TRAININGmay have benefits for

brain health, at least in rats. When rats lift

weights, they gain strength and also change

the cellular environment inside their

brains, improving their ability to think, ac-

cording to a notable new study of resistance

training, rodents and the workings of their

minds.

The study finds that weight training, ac-

complished in rodents with ladders and

tiny, taped-on weights, can reduce or even

reverse aspects of age-related memory

loss. The finding may have important brain-

health implications for those of us who are

not literal gym rats.

Most of us discover in middle age, to our

chagrin, that brains change with age and

thinking skills dip. Familiar names, words

and the current location of our house keys

begin to elude us.

But a wealth of helpful past research indi-

cates that regular aerobic exercise, such as

walking or jogging, can prop up memory

and cognition. In these studies, which have

involved people and animals, aerobic exer-

cise generally increases the number of new

neurons created in the brain’s memory cen-

ter and also reduces inflammation. Un-

checked, inflammation in the brain may

contribute to the development of dementia

and other neurodegenerative conditions.

Far less has been known, though, about

whether and how resistance training af-

fects the brain. A few studies with older peo-

ple have linked weight training to improved

cognition, but the studies have been small

and the linkages tenuous. While re-

searchers know that lifting weights builds

muscle, it is not yet clear how, at a molecu-

lar level, it would affect the cells and func-

tions of the brain.

So, for the new study, which was pub-

lished this month in the Journal of Applied

Physiology, Taylor Kelty, a Ph.D. candidate

at the University of Missouri in Columbia,

began to consider rats and ladders. He and

his collaborators knew that to closely study

brain changes related to resistance train-

ing, they would need to induce animals to

lift weights. But how?

Mr. Kelty’s solution, a modification of

methods used in earlier studies, involved a

100-centimeter-long ladder (a little over

three feet) and bags of weighted pellets

taped to the rats’ rear ends. The animals re-

ceived a Froot Loop when they reached the

top of the ladder and soon started climbing

willingly, even without rewards. After sev-

eral weeks, the climbers showed increased

muscle mass, indicating that the activity

was effective weight training.

Next, to test the training’s brain effects,

Mr. Kelty and his colleagues injected a sepa-

rate group of animals with a substance

known to induce inflammation in the brain,

creating a rodent form of mild cognitive im-

pairment or early dementia.

Half of these rats then began a weekly

program of weight training. As the climbing

became easier, the mass of the pellets in

their bags was increased, just as people pro-

gressively add to the weight they lift at

gyms.

After five weeks, all of the animals, in-

cluding an untouched control group, were

loosed individually into a brightly lit maze

with a single, darkened chamber. Rodents

gravitate toward dark places and during re-

peated visits to the maze, the animals would

be expected to learn the location and aim for

that chamber.

But their success differed. In the first few

tests, the control animals were fastest and

most accurate, and the rodents with mild

cognitive impairments faltered. With a little

practice, though, the weight-trained ani-

mals, despite their induced cognitive im-

pairments, caught up to and in some cases

surpassed the speed and accuracy of the

controls.

The weight training had “effectively re-

stored” their ability to think, Mr. Kelty said.

The untrained animals with mild cogni-

tive impairments, meanwhile, continued to

lag far behind the others in their ability to

find and recall the chamber.

Finally, to better understand how ladder

climbing might have changed the rats’

brains and minds, Mr. Kelty and his collabo-

rators microscopically examined brain tis-

sue from each of the groups. As expected,

they found signs of inflammation in the

brains of the animals that had been injected.

But they found, too, that the memory cen-

ters of the brains in the weight trainers

teemed now with enzymes and genetic

markers that are known to help kick-start

the creation and survival of new neurons,

while also increasing plasticity, which is the

brain’s ability to remodel itself.

In effect, the brains of the weight-trained

rats were remaking themselves to resemble

those of brains that had not been inflamed

and impaired.

Of course, this was a study with rats, and

rats are not people. We rarely weight train

by climbing ladders with heavy bags

strapped to our rears, for one thing. So, it is

impossible to know from this experiment if

our brains will respond in quite the same

way to lifting weights.

The study also cannot tell us whether aer-

obic exercise leads to similar, differing or

complementary molecular changes in our

brains, or if healthy people gain the same

benefits as those with impairments.

But the findings are suggestive, Mr. Kelty

said.

“I think it’s safe to say that people should

look into doing some resistance training,”

he said. “It’s good for you for all kinds of

other reasons, and it appears to be neuro-

protective. And who doesn’t want a healthy

brain?”

PHYS ED GRETCHEN REYNOLDS

Resistance training seems to

help create new neurons

related to memory in rats.

GETTY IMAGES

‘I think it’s safe to say

that people should look

into doing some

resistance training.’

TAY LO R K E LT Y

UNIVERSITY OF MISSOURI

Lifting Weights Kick-Starts the Brain

I noticed my first gray hair during my

medical residency. It sneaked up on me at

the end of a long, frenzied shift — one of

those nights when Murphy’s Law seems

stronger than the law of gravity. Two of my

patients did slip and fall, though, so New-

ton made a strong showing too.

The next day, I found another gray. Then

another and another, until I stopped count-

ing.

I was in my mid-20s, and it was the first

time I’d noticed my body aging — not get-

ting stronger or faster or wiser, but start-

ing its decline. The human body performs

so many impressive functions, I thought:

It heals wounds, clears waste, digests

Doritos. Can’t it find a little pigment to

keep my hair colored?

This month, a new cohort of medical

school graduates began their residencies.

It’s no secret that medical training is an in-

tense, sometimes grueling, process. But a

new study shows how long hours, dis-

rupted sleep and constant stress can take a

biological toll on newly minted doctors.

Down to the level of their genes.

Researchers at the University of Michi-

gan tested the DNA of 250 first-year medi-

cal residents around the country. They

took samples of their saliva to examine the

length of their telomeres — the protective

caps at the ends of chromosomes that pre-

vent DNA damage — before and after the

first year of residency.

Telomeres shorten every time our cells

replicate, acting as a kind of fuse at the end

of DNA. Once they become too short, cells

know that it’s time to retire or self-destruct.

Telomere attrition also plays a role in the

aging process and is linked to many age-

related diseases, including diabetes, can-

cer and heart disease.

Researchers found that the DNA of first-

year residents aged six times fasterthan

normal. Telomeres usually shrink at a rate

of about 25 DNA base-pairs per year, but

first-year medical residents experienced a

decline of more than 140 base-pairs on av-

erage. Residents who worked longer shifts

or more hours over all were at even higher

risk: Telomere shrinkage increased stead-

ily with the number of hours worked, but

skyrocketed for those working more than

75 hours per week to over 700 base-pairs.

“Most prior research on residency well-

being has used self-reported question-

naires,” said Dr. Srijan Sen, the study’s sen-

ior author and an associate professor of

psychiatry at the University of Michigan.

“We hope that showing measurable phys-

iological effects at the cellular level will

help catalyze residency reforms that really

move the needle.”

How long and how hard trainees should

work is a subject of perennial debate in

medicine. But it has new urgency amid

growing recognition of widespread anxi-

ety, depression and burnout among medi-

cal trainees and physicians.

This study comes on the heels of other

research showing that doctors in training

lose three to seven hours of sleep per week

and are much less physically active com-

pared to their pre-residency lives. For

some, a vicious cycle emerges: short sleep

leads to worse mood the next day, which in

turn makes it harder to sleep at night, cul-

minating in a chronic depressive state.

The solution is not simply to reduce

work hours — though avoiding extremely

long workweeks would help. Becoming a

doctor requires intense, repeated, con-

stant immersion, such that diagnosis and

treatment enter a kind of muscle memory.

Most residents, some of whom are ap-

proaching 40 when they finish training,

would probably balk at an offer to trade

shorter hours for more years of training —

even if it does cost them a little telomere.

But there are opportunities to improve

well-being in medical training — many of

which are commonplace in other indus-

tries. Consider something as basic as

healthy food, which can be surprisingly

scarce for doctors working evening or

weekend shifts in the hospital. While the

20-somethings at Google and Facebook en-

joy sparkling water and organic vegeta-

bles, most medical residents scrounge for

greasy pizza, leftover Thai food and sugary

soda — something close to the opposite of

what they recommend for their patients.

It also matters howresidents work all

those hours. Training programs should re-

duce the number of day-to-night transi-

tions residents have to make, as these can

lead to circadian rhythm disruptions and

mood problems. All residencies incorpo-

rate lectures and educational conferences,

but doctors in training are often too busy

juggling pagers, paperwork or other de-

mands to attend. Ensuring residents can

actually participate in these educational

activities would create a sense that learn-

ing is a real priority. And having more flexi-

bility and autonomy over one’s work sched-

ule is critical. Long hours are tough, but

having to miss a close friend’s wedding is

what really hurts.

Finally, structured wellness programs

are emerging. Stanford’s Balance in Life

program, started in 2011 after the suicide of

a surgical residency graduate, provides

trainees with a comprehensive set of re-

sources to support professional and per-

sonal well-being. A mentorship program al-

lows junior residents to meet regularly

with senior trainees and faculty members

to discuss their concerns and goals. (Prior

research has shown that the quality of resi-

dent-faculty interactions is linked to de-

pression scores.)

Every six weeks, residents also meet

with a clinical psychologist to share chal-

lenging experiences and discuss personal

issues. While on call, they have access to a

dedicated refrigerator stocked with health-

ful snacks and beverages. And all residents

are encouraged to have regular checkups

with their own doctor and dentist — an elu-

sive luxury during medical training.

Medical training is — and needs to be —

intense. Developing the skills and intuition

needed to care for patients independently

requires a certain exhaustive immersion.

But too often our current system strains,

instead of supports, trainees along their

journey. That’s not good for doctors or for

patients.

Why Young Doctors Get Gray Hair

Grueling hours, disrupted

sleep and constant stress takes

a biological toll, a study finds.

GETTY IMAGES

By DHRUV KHULLAR, M.D.

Researchers found that

the DNA of first-year

residents aged six times

faster than normal.

DHRUV KHULLAR, M.D., M.P.P.

(@DhruvKhullar) is a physician and assistant

professor of health care policy at Weill Cornell

Medicine, and director of policy dissemination

at the Physicians Foundation Center for Physi-

cian Practice and Leadership.