good for the heart is good for the brain.”
the advice a physician might give to older patients who are concerned about
staying mentally sharp as they get older. We know very well that physical
activity keeps the heart healthy, and in recent years we have begun to
understand how exercise affects the brain.
a collective term referring to various structural and functional brain changes
that occur in response to experience. In a symposium at the 46th
annual meeting of the Society for Neuroscience in San Diego in November,
researchers in the field discussed how exercise benefits the brains of healthy
older adults and those of people with psychiatric and neurological diseases.
Kirk Erickson of
the University of Pittsburgh explained that most of us experience age-related
decline in cognitive function, with abilities such as inductive reasoning,
perceptual speed, and verbal memory declining sharply from about 60 years of
activity offers significant protection against age-related cognitive decline,
however, and can improve
mental function in older adults. [See A Purposeful Life is a Healthy Life]
then described a number of longitudinal intervention studies performed in his
lab investigating the underlying mechanisms by which exercise benefits brain
structure and function in healthy older adults.
2009, Erickson and his colleagues reported that higher levels of aerobic
exercise in elderly adults are associated with increased volume
of the hippocampus, a brain structure known to be critical for memory
formation, and that this in turn is related to enhanced spatial memory. [See One Man's Continuing Contribution to the Science of Memory]
They went on to show that higher fitness levels are also associated with greater
prefrontal cortex volume and better executive function, and that exercise
enhances the integrity
of white matter tracts throughout the brain.
exercise appears to have a protective effect on the brain's gray and white
matter, making both more resilient to the effects of aging. Until recently, it
was thought that the distribution of white matter in the brain was highly
stable, but we now know that it can change
rapidly in response to experience. And although studies consistently show
that exercise increases
expression of growth factor BDNF, it's still not clear exactly how the
observed volume increases occur; they could be due to the production of new
brain cells, the formation of new synaptic connections, or a combination of
believe that exercise affects every organ of the body, and it's very likely
that there are a multitude of pathways by which it affects the brain,” said
Erickson, “but we can now begin to think about how changes at the molecular and
cellular level influence behavioral outcomes.”
added that we still know very little about individual differences in how
exercise affects the brain, and that people generally dislike the term “exercise,”
which may discourage them from participating in research. He and his colleagues
are now recruiting participants for the REACT! trial, a pilot
study that will compare the effects of African dance and an educational
discussion group on brain health, fitness levels, and quality of life in older
African Americans, who are at higher risk of age-related cognitive decline than
Sarah McEwan of
the University of California, Los Angeles described her studies into how
exercise benefits brain function in people diagnosed with schizophrenia.
Schizophrenia is a severe, long-term mental health condition with symptoms that
include delusions of persecution or grandeur, visual and auditory
hallucinations, and disordered patterns of thought and behavior.
studies have shown that people who have had schizophrenia for between 5 and 20
years have less grey matter volume in
the dorosolateral prefrontal cortex. “This part of the brain is important
for higher order processes such as top-down control, attention, and problem-solving,”
McEwan said. “Although anti-psychotics are excellent for treating voices and
delusions, there's nothing to treat the core cognitive dysfunctions, which are
the most debilitating aspects of the disease.”
year, McEwan's lab published the first empirical study to examine the benefits
of regular physical activity for patients in the early stages of the disease.
They scanned the brains of 14 young adults who were experiencing their first
schizophrenic episode, and found that those who reported having low levels of
physical activity had reduced grey matter volume in the prefrontal cortex and
hippocampus compared with the “high activity” group. Patients who reported
greater levels of overall physical activity also performed slightly better on
tests of verbal memory and social cognition.
these preliminary findings suggest that exercise-based interventions could improve brain
health and cognitive function in patients experiencing their first
schizophrenic episode. The findings need to be replicated in a larger
study, however, and they do not address the effects of exercise in patients who
have had the disease for longer periods of time.
deemed to be at high risk of developing schizophrenia tend to be more
sedentary,” McEwan added, “and the first psychotic episode seems to be an
excellent window during which we can try to intervene and improve patients'
prognosis later on in life.”
recent research suggests that exercise can also be of benefit to people
diagnosed with Parkinson's disease (PD), a progressive neurodegenerative
disorder caused by the death of dopamine-producing neurons in the midbrain. PD
leads to involuntary, shaky movements and other motor problems, as well as
of the University of Southern California and her colleagues have been examining
rodent models of Parkinson’s and translating their findings to studies in
the mouse models, neuronal death reduces dopamine levels in the striatum, a
deep brain structure involved in reward, motivation, and movement, which
normally receives inputs from the midbrain. This is accompanied by loss of
dendritic spines, the tiny, finger-like protuberances at which neuronal
signaling takes place.
and her colleagues have shown that treadmill exercise
reverses the loss of dendritic spines in the striatum in a mouse model of
Parkinson’s by promoting the formation of new synaptic connections. And in a
small pilot study of patients with early Parkinson’s published in 2013, they showed
that intensive treadmill training elevates dopamine receptor
levels in the striatum, and also improved patients’ postural control.
the meeting, Petzinger presented preliminary evidence that exercise induces
changes in neural circuits involved in attention. She noted, however, that some
forms of exercise involve motor learning, and that this is likely to contribute
to the protective effects.
argues that exercise does not benefit overall brain health, but rather that different
forms of exercise induce changes in specific neural circuits. She is now
involved in a larger study comparing the effects of cardiovascular training and
skill-based exercises in people with Parkinson’s.
“What we’re beginning
to see is some evidence that both cardiovascular fitness and motor-related
fitness seem to be associated with improved prefrontal cortex-related
cognition,” she said. “We can now tease apart how exercise type may impact
specific circuits and brain areas involved in cognition.”