Alzheimer's, Dementia & Mental Health
Alzheimer’s Disease Preceded by Shrinking in
Hippocampus Area of Brain
Study finds those with highest rates of shrinkage
were two to four times as likely to develop dementia
March 17, 2009 - People who have lost brain cells
in the hippocampus area of the brain are more likely to develop
dementia, according to a study published in the March 17, 2009, print
issue of Neurology, the medical journal of the American Academy
of Neurology.
The study involved 64 people with Alzheimer’s
disease, 44 people with mild cognitive impairment, which is the stage of
memory problems that precedes Alzheimer’s disease, and 34 people with no
memory or thinking problems.
MRI scans were performed on all of the participants
at the beginning of the study and again an average of a year and a half
later. During that time, 23 of the people with mild cognitive impairment
had developed Alzheimer’s disease, along with three of the healthy
participants.
The researchers measured the volume of the whole
brain and the hippocampus area, which is affected by Alzheimer’s
disease, at the beginning and end of the study, and calculated the rate
of shrinkage in the brain over that time.
For the people who did not have dementia at the
beginning of the study, those with smaller hippocampal volumes and
higher rates of shrinkage were two to four times as likely to develop
dementia as those with larger volumes and a slower rate of atrophy.
“This finding seems to reflect that at the stage of
mild cognitive impairment, considerable atrophy has already occurred in
the hippocampus,” said study author Wouter Henneman, MD, of VU
University Medical Center in Amsterdam, The Netherlands.
“In people who already have Alzheimer’s disease,
the loss of nerve cells is more widespread throughout the brain.”
Source Information
The American Academy of Neurology, an association
of more than 21,000 neurologists and neuroscience professionals, is
dedicated to promoting the highest quality patient-centered neurologic
care. A neurologist is a doctor with specialized training in diagnosing,
treating and managing disorders of the brain and nervous system such as
multiple sclerosis, restless legs syndrome, Alzheimer’s disease,
narcolepsy, and stroke.
For more information about the American Academy of
Neurology, visit
www.aan.com.
About Hippocampus
The
hippocampus is a brain structure located inside the medial temporal lobe
of the cerebral cortex, and therefore is part of the telencephalon
(forebrain). It belongs to the limbic system and plays major roles in
short term memory and spatial navigation. Humans and other mammals have
two hippocampi, one in each side of the brain. In rodents, where it has
been studied most extensively, the hippocampus is shaped something like
a banana. In humans it has a curved and convoluted shape that reminded
early anatomists of a seahorse. The name, in fact, derives from the
Greek word for seahorse (Greek: ιππος, hippos = horse, καμπος, kampos =
sea monster).
In Alzheimer's disease the hippocampus is one of
the first regions of the brain to suffer damage; memory problems and
disorientation appear among the first symptoms. Damage to the
hippocampus can also result from oxygen starvation (anoxia),
encephalitis, or medial temporal lobe epilepsy. People with extensive
hippocampal damage may experience amnesia, that is, inability to form or
retain new memories.
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Read more at Wikipedia
