New dementia research from the
Netherlands has revealed that smoking and diabetes are associated with calcium
buildup in a part of the brain that is important for memory.
Both smoking and
diabetes are found to be linked to calcium buildup in the brain.
In a report published in the
journal Radiology, the study investigators describe how they
analyzed brain CT scans of patients with memory problems.
According to lead
study author Dr. Esther J.M. de Brouwer, from the Department of Geriatrics at
the University Medical Center in Utrecht, in the Netherlands, "We know
that calcifications in the hippocampus are common, especially with increasing
age."
She and her colleagues
found that, in addition to advancing age, diabetes and smoking were also linked to calcium deposits, or calcifications, in the hippocampus.
Dementia and the
hippocampus
Because the
hippocampus is a structure in the brain important for short- and long-term
memory, it is the subject of much research on dementia, a disease that affects some 50 million people worldwide.
This research has
shown, for example, that the hippocampus is "especially
vulnerable to damage" during the
early development of Alzheimer's disease, which is the main cause of dementia.
Other causes of
dementia include damage to the blood supply to the brain, buildup of abnormal
proteins called Lewy bodies, and inflammation.
However, Dr. de
Brouwer and team note that current dementia research on the hippocampus tends
to focus on degeneration of brain cells and tissues as opposed to abnormalities
in the blood supply, or vascular system, that feeds them.
The scientists'
findings could be significant because they support the idea that the
"calcifications may be of vascular origin."
New type of CT scan
A distinguishing
feature of the study is that it was able to take advantage of a new type of
scan known as a "multiplanar brain CT scan."
This type of CT scan
lets radiologists differentiate between calcium buildup in the hippocampus and
that in neighboring structures such as the choroid plexus.
Dr. de Brouwer
explains that this scan type also "makes it possible to see the
hippocampus in different anatomical planes; for example, from top to bottom,
right to left, and front to back."
The team examined the
multiplanar brain CT scans of around 2,000 people who had attended a hospital
memory clinic in the Netherlands during 2009–2015. The age of the patients
ranged between 45 and 96 years. Their average age was 78.
The CT scans had all
been performed as part of diagnostic tests that also included assessment of
cognitive function.
The researchers had
two goals in mind for their study. One was to investigate any links between
risk factors known to cause vascular problems — such as smoking, diabetes,
and high blood pressure — and hippocampal calcifications.
The other goal of the
study was to discover whether calcium buildup in the hippocampus has an effect
on cognitive function.
Smoking and diabetes
'likely risk factors'
When they analyzed the
CT scans, the scientists found that 19 percent of all the study participants
had calcifications in their hippocampus.
They also discovered
that "older age," smoking, and diabetes "were associated with
the presence of hippocampal calcifications."
The study design did
not permit the scientists to be sure that smoking and diabetes actually raise
the risk of hippocampal calcifications.
However, Dr. de
Brouwer says that they "do think that smoking and diabetes are risk
factors."
There is evidence to
suggest that hippocampal calcifications are a hallmark of vascular disease and
"[i]t is well-known that smoking and diabetes are risk factors for
cardiovascular disease," she adds.
No link to cognitive
function
The team was puzzled
that the study found no links between calcium buildup in the hippocampus and
cognitive function.
Dr. de Brouwer
suggests that this could have been due to some of the limitations of their
methods and design.
One limitation, for
example, was the fact that there was no "control group" of healthy
subjects; all the participants were patients at a memory clinic and had
disorders ranging from cognitive impairment to vascular dementia and
Alzheimer's disease.
Another explanation
might lie in the fact that there are several layers in the hippocampus,
"and it is possible that the calcifications [found in the study] did not
damage the hippocampal structure that is important for memory storage,"
notes Dr. de Brouwer.
She and her colleagues
are now expanding the research to include other groups in a bid to better
understand how calcium buildup in the hippocampus might impact cognitive
function
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