Use It or Lose It
The Science Behind an Active Mind
and Alzheimer's Disease
Drs. Dennis Selkoe
(standing) and Shaomin
Li led a study showing that prolonged and
stimulation by an enriched
environment may have beneficial effects
"Use it or lose it." The saying could apply
especially to the brain when it comes to protecting us against Alzheimer's
disease. Previous studies have shown that keeping the mind active, exercising
and social interactions may help delay the onset of dementia in Alzheimer's
Now, a new study led by Dennis Selkoe, MD, co-director of
the Center for Neurologic Diseases in the BWH Department of Neurology, provides
specific scientific evidence supporting the concept that prolonged and
intensive stimulation by an enriched environment, especially regular exposure
to new activities, may have beneficial effects in delaying one of the key
negative factors in Alzheimer's disease.
Alzheimer's disease occurs when a protein called amyloid beta accumulates and forms "senile
plaques" in the brain. This protein accumulation can block nerve cells in the
brain from properly communicating with one another. This may gradually lead to
an erosion of a person's mental processes, such as memory, attention, and the
ability to learn, understand and process information.
The BWH researchers used a wild-type mouse model
when evaluating how the environment might affect Alzheimer's disease. Unlike
other pre-clinical models used in Alzheimer's disease research, wild-type mice tend
to more closely mimic the scenario of average humans developing the disease
under normal environmental conditions, rather than being strongly genetically
pre-disposed to the disease.
Selkoe and his team found that prolonged exposure
to an enriched environment activated certain adrenalin-related brain receptors
which triggered a signaling pathway that prevented the amyloid beta protein
from weakening the communication between nerve cells in the brain's "memory
center," the hippocampus. The hippocampus plays an important role in both short-
and long-term memory.
an Old Mouse New Tricks
The ability of an enriched, novel environment to prevent
amyloid beta protein from affecting the signaling strength and communication
between nerve cells was seen in both young and middle-aged wild-type mice.
"This part of our work suggests that prolonged
exposure to a richer, more novel environment beginning even in middle age might
help protect the hippocampus from the bad effects of amyloid beta, which builds
up to toxic levels in one hundred percent of Alzheimer patients," said Selkoe.
Moreover, the scientists found that exposing the
brain to novel activities in particular provided greater protection against
Alzheimer's disease than did just aerobic exercise. According to the
researchers, this observation may be due to stimulation that occurred not only
physically, but also mentally, when the mice moved quickly from one novel
object to another.
"This work helps provide a molecular mechanism for
why a richer environment can help lessen the memory-eroding effects of the
build-up of amyloid beta protein with age," said Selkoe. "They point to basic scientific reasons
for the apparent lessening of Alzheimer's disease risk in people with
cognitively richer and more complex experiences during life."
Prolonged exposure to an
enriched environment helped trigger a signaling pathway that prevented proteins
related to Alzheimer's disease from weakening communication between nerve cells
in the brain.