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This is an odd admission for a psychiatrist to make, but I’ve never been
very good at sitting still. I’m antsy in my chair and jump at any
opportunity to escape it. When I’m trying to work out a difficult
problem, I often stand and move about the office.

Keeping Perspective: The Role of the Hippocampus

Sitting at your desk all day or on your sofa watching TV could make you
stupid, scientists have suggested.




We’ve known for a while that sitting for long stretches of every day has
myriad health consequences, like a higher risk of heart disease and
diabetes, that culminate in a higher mortality rate. But now a new study
has found that sitting is also bad for your brain. And it might be the
case that lots of exercise is not enough to save you if you’re a couch
potato the rest of the time.

In a healthy brain, the amygdala works in conjunction with a structure
adjacent to it in the temporal lobe called thehippocampus(seeFigure

Researchers have discovered those with a sedentary lifestyle have a
smaller brain region important in forming memories.




A study published last week, conducted by Dr. Prabha Siddarth at the
University of California at Los Angeles, showed that sedentary behavior
is associated with reduced thickness of the medial temporal lobe, which
contains the hippocampus, a brain region that is critical to learning
and memory.

The hippocampus is a crucial and intriguing part of the your brain
because of its multiple roles. It …

The study, by researchers at the University of California at Los
Angeles, adds to a growing list about the dangers of sitting for too

加州大学洛杉矶分校(University of California at Los



The researchers asked a group of 35 healthy people, ages 45 to 70, about
their activity levels and the average number of hours each day spent
sitting and then scanned their brains with M.R.I. They found that the
thickness of their medial temporal lobe was inversely correlated with
how sedentary they were; the subjects who reported sitting for longer
periods had the thinnest medial temporal lobes.

• Constructs conscious, autobiographical memories.

An array of evidence has already linked the bad habit to heart disease,
diabetes, several forms of cancer and an early death in recent years.




The implication is that the more time you spend in a chair the worse it
is for your brain health, resulting in possible impairment in learning
and memory.


But the new research, derived from 35 participants, suggests sitting for
too long could even boost the risk of dementia.


• Helps to put emotional reactions in context of time and place.


Of course, the study cannot prove that this link is causal. It’s
possible that people with pre-existing cognitive problems might just be
more sedentary. Still, the researchers screened the subjects to rule out
major medical and psychiatric disorders, so this explanation is


Those with the lazy lifestyles had less grey matter in the medial
temporal lobe (MTL) – even if they went for regular brisk walks, cycle
rides or jogs.


• Gives birth to new brain cells (neurogenesis).


What’s also intriguing is that this study did not find a significant
association between the level of physical activity and thickness of this
brain region, suggesting that exercise, even strenuous exercise, may not
be enough to protect you from the harmful effects of sitting.


A decline in this area has repeatedly been shown to be an early warning
sign of Alzheimer’s disease in middle-aged and elderly patients.


• Helps to regulate the stress response system (Andersen, Morris, Amaral
Bliss, & O’Keefe, 2007).


This all puts me in mind of the Peripatetics, followers of Aristotle,
who conducted their philosophical inquiries while strolling about the
Lyceum in ancient Athens. Sounds as if they were on to something.


The study, published in?PLOS ONE, quizzed the volunteers, who were
aged between 45 and 75, about their levels of exercise.


You can appreciate the many roles of the hippocampus if you have ever
known someone with dementia; the hippocampus is eventually destroyed in
patients with Alzheimer’s disease.


But what is it about walking – besides increased blood flow to the brain