New combination of brain imaging and genetic analysis may help identify people at early risk for Alzheimer’s disease

February 8, 2011

TORONTO, Feb. 8 /PRNewswire/ – A new study from the Centre for Addiction and
Mental Health (CAMH) has found evidence suggesting that a variation of
a specific gene may play a role in late-onset Alzheimer’s, the disease
which accounts for over 90% of Alzheimer’s cases. This innovative study
has combined genetics and brain imaging to determine who may be at risk
for developing late-onset Alzheimer’s disease long before symptoms

The gene, which is called brain-derived neurotrophic factor (BDNF), is
crucial to maintaining healthy function of the brain, primarily the
brain’s memory centre of the hippocampus and entorhinal cortex, and is
responsible for learning and memory function.  Past research has found
that less BDNF is present in the memory centre of those diagnosed with
Alzheimer’s disease. However genetic association studies alone have not
produced definite findings regarding this gene. Instead, a combination
of genetics and brain imaging were used to demonstrate clear effects of
this gene in the brain.

In the study published today in the Archives of General Psychiatry, a variation of the BDNF gene called val66met, was tracked and examined
in healthy individuals to see what effect it had on the brain.
Genotyping was used to determine which study participants carried the
gene variation. Then two types of brain imaging — high-resolution
magnetic resonance imaging (MRI) cortical thickness mapping and
diffusion tensor imaging (DTI) (an MRI-based technique that measures
key structural connections in the brain)– were applied to measure the
physical structures of the brain in each individual. This combination
of genetic screening and imaging found that BDNF val66met gene
variation influenced exactly those brain structures and connections
that deteriorate at the earliest phases of Alzheimer’s disease.

“Our sample consisted of healthy adults who passed all cognitive testing
and displayed no clinical symptoms of Alzheimer’s disease, yet the
brains of those who carried the gene variation had differences in their
brain structures consistent with changes we see in people at the
earliest stages of Alzheimer’s disease,” said Dr. Aristotle Voineskos,
physician and scientist at CAMH, and principal investigator of the

Participants who carried the variation were more likely to have thinner
temporal lobe structures and disrupted white matter tract connections
leading into the temporal lobe – the same structures and neural
networks that have deteriorated in the brains of Alzheimer’s patients
when their brains are examined post-mortem.

“In the past, Alzheimer’s disease could only be diagnosed and treated
once outward symptoms became present,” added Dr. Voineskos. “Early
identification is key because, in addition to seeking therapeutic
treatments early to reduce suffering, delaying Alzheimer’s onset by
only two years has the potential of saving the Canadian health care
system nearly $15 billion over the next 10 years. The combination of
brain imaging and genetics is a key approach that may help us to
identify people at risk for Alzheimer’s disease.”

This breakthrough in image-genetics research can be valuable in the
research of other brain diseases and will enable researchers to examine
how a gene affects the brain and possibly intervene before a person
develops an illness.

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The Centre for Addiction and Mental Health (CAMH) is Canada’s largest
mental health and addiction teaching hospital, as well as one of the
world’s leading research centres in the area of addiction and mental
health. CAMH combines clinical care, research, education, policy
development and health promotion to help transform the lives of people
affected by mental health and addiction issues.  CAMH is fully
affiliated with the University of Toronto, and is a Pan American Health
Organization/World Health Organization Collaborating Centre. For more
information, please visit www.camh.net.

SOURCE Centre for Addiction and Mental Health

Source: newswire

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