The Globe and Mail - 21.10.2019

A14 OTHEGLOBEANDMAIL | MONDAY,OCTOBER21,

LIFE&ARTS HEALTH&WELLNESS| OPINION| PUZZLES | WEATHER

S

can a list of “brain foods”
and you’re bound to find
blueberries, fish and leafy
greens on it. These specific foods
have been linked to improved
memory, concentration and
overall cognitive function in past
research.
The problem, though, is that
we don’t eat foods or consume
nutrients in isolation. The foods,
nutrients and phytochemicals in
a varied diet are thought to work
synergistically to exert health
benefits.
In recent years, nutrition re-
search has shifted to examining
“dietary patterns” in order to cap-
ture the complexity of diet. A die-
tary pattern is defined as the
quality, quantity, variety and
combinations of foods eaten on a
regular basis. One of the best-
known dietary patterns is the

well-studied Mediterranean diet.

In Mediterranean countries, ad-

herence to this way of eating has

been associated with a slower

rate of cognitive decline and a

lower risk of Alzheimer’s disease.

Few studies, however, have ex-

plored the link between a Medi-

terranean diet and cognitive

health in non-Mediterranean

countries. Now, two of the largest

studies conducted to date, pub-

lished in the October issue of the

American Journal of Clinical Nu-

trition, provides further evidence

that a Mediterranean dietary pat-

tern benefits cognitive health in

adults who live outside of the

Mediterranean region.

THELATESTFINDINGS

In the United Kingdom, research-

ers evaluated dietary data that

was collected from 8,009 healthy

older adults, from ages 40 to 79,

between the years 1993 and 1997.

Participants were then followed

for 13 to 18 years, at which time

they underwent a battery of cog-

nitive function tests.

Those whose diets closely

matched the Mediterranean diet

had significantly better overall

cognitive function and perform-

ance on cognitive tests than par-

ticipants who had low Mediterra-

nean diet scores. The researchers

accounted for factors that could

influence the risk of cognitive im-

pairment, including body mass

index, smoking status, physical-

activity level and education.

The second study, conducted

among 16,948 healthy Chinese

adults, examined whether close-

ly adhering to a healthy dietary

pattern in mid-life influenced the

risk of cognitive impairment later

in life. (Mild cognitive impair-

ment may increase the risk of de-

veloping Alzheimer’s disease.)

Participants’ diets were scored

based on how closely they adher-

ed to the Mediterranean diet, the

DASH (Dietary Approaches to

Stop Hypertension) diet, a plant-

based diet and two other healthy

eating indices. Diet quality was

assessed at ages 45 to 75; cogni-

tive function was evaluated 20

years later. Compared with par-

ticipants whose diets adhered the

least to any healthy dietary pat-

tern, those with diets that closely

matched one had a significantly

lower risk of cognitive impair-

ment later in life. The strongest

protective effect was attributed

to the Mediterranean diet.

LIMITATIONS

Cognitive function was measured

once, at the end of each study, so

the researchers weren’t able to

capture possible cognitive de-

cline over time. Dietary intake

was assessed only at the start of

each study so it’s not known if

participants changed their diets

during the follow-up periods. As

well, the results may have been

influenced by factors that weren’t

accounted for, such as childhood

cognition, a variable that‘s relat-

ed to healthier food choices and,

in turn, better cognitive function.

Even so, these two large stud-

ies add to increasing evidence

that a Mediterranean dietary pat-

tern helps maintain cognitive fit-

ness as we age.

WHAT’SINA

MEDITERRANEANDIET?

The Mediterranean diet is a

plant-forward way of eating

that’s characterized by a daily in-

take of vegetables, fruits, whole

grains, beans and lentils and

nuts. The principle fat, which is

used liberally, is extra virgin olive

oil, high in monounsaturated fat.

Fish, chicken, eggs, yogurt and

cheese are consumed in moder-

ate amounts, whereas red meat,

sweets and pastries, butter and

highly processed foods are eaten

infrequently. Wine is consumed

in small amounts, typically with

meals.

Herbs and spices, rich in anti-

inflammatory phytochemicals,

are used to flavour foods.

It’s thought that the Mediter-

ranean diet protects the brain by

providing nutrients, antioxidants

and phytochemicals that reduce

inflammation and protect cells

from free radical damage. Com-

ponents of whole grains, fruits

and vegetables also influence the

brain by supporting a healthy gut

microbiome. It’s the combined

effect of the Mediterranean die-

tary pattern that counts, not its

individual foods.

Mediterraneandietcouldprovideaboostforthebrain

Twostudiesconducted

inU.K.,Chinasuggest

dietarypatternmay

inhibitcognitivedecline

LESLIE
BECK

OPINION

TheMediterraneandietisaplant-focusedmethodofeatingthatis

characterizedbyadailyintakeofvegetables,fruits,wholegrains,beans

andlentilsandnuts.IVOGRETENER

Toronto-basedprivatepractice
dietitian,anddirectoroffood
andnutritionatMedcan

| NEWS

T

he idea that depression

might be caused by a chem-

ical imbalance in the brain

• and not a moral failing – grew in
  popularity with the invention of
  the drug Prozac in the late ‘80s,
  and later with the marketing of
  this and other antidepressants.
  This viewpoint helped reduce
  the stigma around mental illness,
  but did not provide a cure-all.
  Rates of depression have risen by
  more than 18-per-cent worldwide
  since 2005, according to the
  World Health Organization. At
  the same time, so too has the con-
  sumption of antidepressants.
  Canada has the world’s fourth-
  highest use of these drugs, ac-
  cording to a recent study from the
  Organisation for Economic Co-
  operation and Development.
  Now, a new theory about the
  cause of depression has emerged:
  That it is a disease caused by the
  body’s immune system. The idea
  is that chronic stress causes hor-
  monal dysregulation, and this
  leads to depression and other in-
  flammatory disorders, such as ar-
  thritis, lupus, heart disease and
  even some forms of cancer.
  One of Canada’s leading pro-
  ponents of this thesis is Dr. Diane
  McIntosh, a Vancouver-based
  psychiatrist, and assistant profes-
  sor at the University of British Co-
  lumbia and author of the new
  book,This is Depression: A Com-

prehensive, Compassionate Guide

for Anyone who Wants to Under-

stand Depression.

She spoke to The Globe and

Mail about cortisol, blueberry

cures and why talking to some-

one is always a good idea.

Inyourbook,yousaythat

depressionshouldbeconsideredan

inflammatoryillness.Whatdoyou

mean?

To understand what inflamma-

tion is and how it causes depres-

sion, you need to understand the

role of the brain’s glial cells. These

are the brain’s caretakers: they

supply the neurons with nutri-

ents and oxygen, protect the

brain from infections and clean

up the brain’s waste products,

such as dead neurons. Depression

can provoke chronically high lev-

els of cortisol, the hormone that

we produce when under stress.

Too much cortisol causes the glial

cells to stop working properly. In-

stead, they start spitting out pro-

teins called pro-inflammatory cy-

tokines. They damage the glial

cells, which causes them to re-

lease more cytokines, causing an

inflammatory cascade.

Ifcortisolisakeyculprit,isstressa

leadingcauseofdepression?

Yes. Chronic stress causes the

body to produce high levels of

cortisol, which can lead to

depression, but depression itself

ramps up the cortisol, which

worsens the depression.

Depressionisn’ttheonlyillness

foundtobecausedbyinflamma-

tion.Heartdisease,HIV,lupus,

arthritis,diabetes,obesity,chronic

painandseveralformsofcancer

havealsobeencalledinflammatory

disorders.Arealloftheserelated?

Yes. We believe inflammation is a

critical factor in the mind-body

connection. Chronic stress causes

an inflammatory cascade, lead-

ing to an increased likelihood of

developing diseases linked to in-

flammation, and those inflam-

matory disorders increase the

risk of depression. This is why a

person who has an inflammatory

disorder such as heart disease or

arthritis is more likely to develop

depression.

Thetheorythatdepressionwas

causedbylowlevelsofbrain

serotonin(calledthe“chemical

imbalancetheory”)waspopularin

the1990sandearly2000s,buthas

beenlargelydiscredited.Isthe

focusoninflammationmerelya

newversionofthis?

No. It’s not that we have aban-

doned the theory of a causal con-

nection between depression and

neurotransmitters such as seroto-

nin and norepinephrine, but we

now realize that the brain is

much more complex and there

are multiple factors involved.

Glial cells regulate neurotrans-

mitter levels too. Looking at in-

flammation, and the relationship

between cortisol, glial cells, and

neurotransmitters helps us un-

derstand what is happening in

the brain and body.

Ifblueberriesareanti-inflammato-

ry,willeatingthemhelpsomeone

whoisdepressed?

You can’t blueberry your way out

of a depression! Nor will a detox

enema help. An anti-inflammato-

ry diet may help to prevent those

illnesses associated with inflam-

mation, including depression,

but it isn’t a form of treatment.

Inyourbook,you’vewrittenabout

exerciseasbothaformofpreven-

tionandtreatmentfordepression.

Howdoesithelp?

Several studies have found that

exercise can be effective as medi-

cation or talk therapy for mild to

moderate depression. Exercise re-

duces cortisol and increases a

critical protein, called brain-de-

rived neurotrophic factor, that is

necessary to grow healthy brain

cells, called neurogenesis. The

benefits of exercise as a treat-

ment depend on the severity of

the depression. Walking or run-

ning each day will always help,

but for a moderate to severe de-

pression, exercise alone isn’t

enough.

Ifdepressionisaninflammatory

illness,howcouldtalkingtoa

therapisthelp?

If a person learns how to reframe

their situation, for example

through cognitive behavioural

therapy, they are learning the

skills to regulate those areas of

the brain associated with process-

ing emotion, such as the amygda-

la.

Over time, new ways of think-

ing, feeling and behaving can be-

come more natural to the person,

even automatic. In essence, each

new skill that is taught by the

therapist to handle stressful sit-

uations lays down new neural

pathways, and these shape how

the brain functions. How a brain

is used determines which parts

grow larger and shrink. In the

long term, what and how we

think moulds the physical shape

of our brain.

Whatabouttalkingtoafriend?

Canthatbeashelpful?

A friend can help by asking ques-

tions such as, “What can I do for

you?” or “How can I be helpful?”

But they shouldn’t try to fix the

problem for you. Having social

support is one of the greatest pro-

tectors against depression, but if

you meet the criteria for a moder-

ate or severe depression, you

need to seek professional help.

SpecialtoTheGlobeandMail

Anewtheoryondepression:It’sadiseasecausedbythebody’simmunesystem

ALEXANDRASHIMO