There are now 67
countries where the life expectancy is at least 75 years old, according to
World Health Organization figures from 2013.
As people live longer, a better understanding of the aging brain is viewed
as key to an improved quality of life. In “Cognitive Function and the Aging Brain: What to Expect,” the title of this month’s Cerebrum article, author
Diane B. Howieson, Ph.D., a
neuropsychologist and associate professor emerita of neurology at the Oregon
Health & Science University, leans on her research and clinical experience
to elaborate on the aging brain and offer insights in some other areas.
You write that we lose cognitive function as we age but gain wisdom from
experience. Is it a wash?
don’t lose cognitive function as much as we lose cognitive efficiency. But it
very much depends on what kind of task you're referring to. Some cognitive
tasks do benefit from wisdom and
experience; particularly where judgment and strategy are involved. But some
cognitive tasks are independent of experience such as, for example, how well
you read something. Reading depends on learning and is not much a function of
wisdom or, for that matter, memory. Normally, when you have a situation that
requires some analysis of what's controlling the problem or the situation, then
wisdom can come in and cause a noticeable benefit.
there other reasons besides longitudinal studies that make it so hard to study
of the main goals in dementia research, including Alzheimer's research, is to
identify the disease in its earliest stage. When we get to the point where we
have a treatment that either prevents progression of the disease or slows it
down, the earlier it can be instituted, the better. What makes Alzheimer's
disease so difficult to study is that the cognitive changes associated with
just normal aging are very, very similar to the earliest symptoms of the
disease. As a result, we usually don't really know whether someone is
progressing to Alzheimer's disease until they’re beyond the earliest stages
when cognitive problems have advanced. That’s the real challenge.
has been loosely linked to staving off cognitive decline. What type and how
much exercise does someone over 75 need, and does gender matter?
are quite a few studies that suggest that exercise is beneficial but not all of
them have shown benefit and some of the studies have been very small. But
nevertheless, overall we think that exercise does benefit brain function. There been some studies that have compared aerobic
exercises with stretching and yoga, and the findings showed that aerobic-like
exercises were more beneficial. I’m unaware of any gender differences.
you also link nutrition to cognitive function?
did a very interesting study at the Oregon Health & Science University
where we looked at nutritional biomarkers of elderly people. We examined their
cognitive functioning as a function of their nutritional pattern. The study subjects were not demented and were
considered normally healthy people. Those that had higher levels of omega fatty
acids and higher levels of good vitamins did better. The ones that definitely
did worse were the ones that had high levels of trans-fat in their blood. The
difference in this study as compared to a lot of studies is that the
nutritional biomarkers were based on blood samples, not on self-reports of what
people said they were eating, which is sometimes inaccurate.
are your thoughts on vitamins and nutritional supplements to stave off
study would suggest that omega fatty acids are good nutritional supplements.
However, not all studies have shown that, so it really depends on whether
someone has the financial resources to buy supplements or whether their
physicians recommend them.
said that as people age they become “more themselves” and tend to get grumpier?
Is this a misnomer?
a way it is. Actually, as people get older they are more likely to suffer from
chronic pain; or limitations in their ability to do daily activities; or the loss
of loved ones. All of these things can lead to depression. Depression, of
course, can cause people to be grumpier. So I think it's probably not a change
as a result of the brain but a change as the result of the mood of people as they are dealing with conditions that
often accompany older age.
there lifestyles choices that one can make when their younger that will help
them with cognitive function as they age?
There is quite a bit of research
suggesting that people who have higher levels of cognitive stimulation
throughout life are going to do better with their cognitive abilities when
they're older than are people who have very limited cognitive stimulation. And
there’s reason to think that learning new and different kinds of skill stimulates
the brain in a different way than just doing the same skill over and over and
over again. People that accept cognitive challenges throughout their life,
either through their work or other activities, will show the benefits when they
you think that funding for research for Alzheimer’s disease and other forms of
dementia falls so far below funding for cancer and heart research?
is such a good question because Alzheimer's disease costs society much more
financially and resource-wise than cancer or heart disease, and yet Alzheimer's
gets a fraction of the funding. It doesn’t make sense to me.
of our articles talk about genetics as our best chance to defeat various
neurobiological disorders. Last Thursday a group of scientists meeting in
Washington called for a moratorium on making inheritable changes to the human
genome. What are your thoughts on tinkering with the DNA of embryos to reduce
the risk of mental disorders such as Alzheimer’s?
It’s an exciting time in genetic
research. The gene alterations that they're able to do now with gene snipping
is very interesting, but researchers have to proceed very carefully because if you
alter a person’s DNA, then that alteration is passed on to that person's
offspring and to subsequent generations. It really has an implication for more
than just one individual. When they move to treating diseases this way, they’re
going to start by picking a disease that has one genetic mutation that can be
snipped out and hope that it is going to be effective.
In about 95 percent of patients with Alzheimer’s disease, many, many
genes are influencing the likelihood the disease will be passed down. There
many diseases like Alzheimer's where it just wouldn't be practical altering DNA
because there are too many genes that are involved and we don’t, at least at
this time, know why some genes cause a predisposition to the disease. Alzheimer’s
is a disease that’s too genetically diverse to treat in this way, at least as
we now understand it. There are three autosomal-dominant (a
gene on one of the non-sex chromosomes that is always expressed, even if only
one copy is present) forms of Alzheimer's disease, which may be a
target sometime in the future. But again, it's less than five percent of the
worldwide cases, so it won’t have a major impact.