Researchers from St. Michael’s Hospital presenting work at the Alzheimer’s Association International Conference 2016 in Toronto
Toronto, July 28, 2016
By Leslie Shepherd
- Mild cognitive impairment could affect driving skills
- Misdiagnosis of Alzheimer’s disease: inconsistencies between clinical diagnoses and autopsy results
Megan A. Hird (left) and Winnie Qian
Researchers from St. Michael’s Hospital were selected to present preliminary results of two projects to the Alzheimer’s Association International Conference 2016 taking place in Toronto, the largest gathering of researchers from around the world focused on Alzheimer’s and other dementias.
One abstract indicates that mild cognitive impairment could affect driving skills and the other explores how many cases of Alzheimer’s disease are misdiagnosed.
In the first study to combine driving simulation and functional magnetic resonance imaging (which measures brain activity by detecting changes associated with blood flow), researchers in the hospital’s Neuroscience Research Program compared the driving behavior of 22 patients with mild cognitive impairment and 17 healthy people.
Mild cognitive impairment, or MCI, causes a slight but noticeable and measurable decline in cognitive abilities, including memory and thinking skills. People with MCI are at an increased risk of developing Alzheimer’s or another form of dementia.
The researchers found that patients with MCI committed more than three times more driving errors, including moving out of the correct lane and collisions, than healthy control drivers (10.18 vs. 3.06 per simulation exercise). Drivers with MCI committed twice as many turning errors overall (0.134 vs. 0.063 errors per turn) and three times as many during left turns with traffic (0.141 vs. 0.044 errors per turn.)
The MRIs showed that patients with MCI activated a more extensive set of brain resources (e.g. regions involved in executive function) for both routine (right turns) and more cognitively demanding aspects of driving (e.g. left turns with traffic).
Furthermore, patients with MCI may be at an increased risk of driving impairment during turning, particularly during left turns with oncoming traffic.
“Safe driving requires the coordination of several parts of the brain responsible for attention, memory, executive function and the ability to identify visual and spatial relationships among objects,” said abstract author Megan A. Hird, a Master’s student in the Neuroscience Research Program of St. Michael’s Keenan Research Centre for Biomedical Sciences.
“But the areas and degree of driving impairment characteristic of individuals with MCI remain unknown. As a result, there are no valid tools to help health-care professionals assess the driving fitness of patients with MCI. Future large-scale research is required to better characterize the driving impairments and corresponding brain activation patterns associated with MCI.”
The second study being presented by St. Michael’s researchers focuses on issues related to the diagnosis and misdiagnosis of Alzheimer’s disease.
The researchers looked at inconsistencies between clinical diagnoses and the results of autopsies in 1,073 people from the National Alzheimer’s Coordinating Center database. They found:
- 41 (78.4 per cent) had a clinical diagnosis and autopsy confirmation of Alzheimer’s
- 116 (10.8 per cent) were diagnosed with Alzheimer’s in the clinic but an autopsy showed they did not have the brain changes necessary for an Alzheimer’s diagnosis (“false positives.”). In other words, some disease or condition other than Alzheimer’s was causing their dementia.
- 116 (10.8 per cent) had Alzheimer’s changes in their brains, but were not clinically diagnosed with Alzheimer’s (“false negatives.”)
“Vascular pathology was the most common cause of a false positive clinical Alzheimer’s diagnosis,” said abstract author Winnie Qian, a Master’s student under Neuroscience Research Program director Dr. Tom Schweizer.
Vascular pathology refers to brain changes caused by cerebrovascular diseases such as ischemic strokes or hemorrhagic strokes.
Dementia with Lewy bodies was the most common cause of a false negative diagnosis.Dementia with Lewy bodies is a type of dementia that shares symptoms with both Alzheimer's disease and Parkinson's disease. It may account for around 10 per cent of all cases of dementia.
“Diagnostic errors can have important implications for patient treatment and outcome.” Qian said. “We need assessment tools with higher sensitivity and specificity to reduce diagnostic errors in Alzheimer’s.”
This paper is an example of how St. Michael's Hospital is making Ontario Healthier, Wealthier, Smarter.
About St. Michael's Hospital
St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in 27 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, care of the homeless and global health are among the hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael's Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.
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