Monthly Archives: mars 2017

Little is known about the role of the brain’s immune system in Alzheimer’s disease. But researchers have now found an early immune response in individuals with a genetic predisposition to Alzheimer’s: their brains showed abnormal immune reactions as early as about seven years before the expected onset of dementia.

These results demonstrate that in cases of Alzheimer’s, inflammatory processes in the brain evolve dynamically and are precursors of dementia. These immune responses can be detected by means of a protein in the cerebrospinal fluid, offering physicians the possibility to trace the progression of the disease. The study results are published in the journal Science Translational Medicine.

The researchers were able to detect increasing immune activity of the brain by measuring levels of the protein “TREM2” in the cerebrospinal fluid. TREM2 is segregated by certain immune cells of the brain – called microglia – and thus reflects their activity. In cases of the inherited form of Alzheimer’s disease, the timing for the onset of dementia can be precisely predicted. The researchers were therefore able to monitor the rise of TREM2 levels years before the expected occurrence of dementia symptoms.

In total, 127 individuals with a genetic predisposition to Alzheimer’s participated in the study. They were on average 40 years old. The vast majority showed no symptoms of dementia or had only minor cognitive impairments. The study was conducted as part of the so-called DIAN project (Dominantly Inherited Alzheimer Network), a worldwide network for research into the inherited form of Alzheimer’s disease.

Paper: « Early changes in CSF sTREM2 in dominantly inherited Alzheimer’s disease occur after amyloid deposition and neuronal injury »
Reprinted from materials provided by DZNE.

People with Parkinson’s disease and cognitive impairment have disruptions in their brain networks that can be seen on a type of MRI, according to a study appearing online in the journal Radiology.

Parkinson’s disease (PD) is a progressive disorder of the central nervous system characterized by tremors or trembling and stiffness in the limbs, impaired balance and coordination. It affects about 10 million people worldwide. As PD progresses, many patients develop mild cognitive impairment (MCI), a decline in cognitive abilities, including thinking, memory and language. MCI can be identified in approximately 25 percent of newly diagnosed PD patients, and patients with MCI progress to dementia more frequently than those with normal cognitive performance.

For the new study, researchers used an MRI technique called diffusion tractography to look for differences in the neural networks of PD patients with and without MCI.

Increasingly, the human brain is understood as an integrated network, or connectome, that has both a structural and functional component. By applying an analytical tool called graph analysis to the imaging results, researchers can measure the relationships among highly connected and complex data like the network of connections in the human brain.

The study group was made up of 170 PD patients, including 54 with MCI and 116 without, and 41 healthy controls. Analysis of imaging results showed that only PD patients with MCI had significant alterations at the brain network level. Measurements of the movement and diffusion of water in the brain, an indicator of the condition of the brain’s signal-carrying white matter, differentiated PD patients with MCI from healthy controls and non-MCI PD patients with a good accuracy. Researchers said the results show that cognitive impairment in PD is likely the consequence of a disruption of complex structural brain networks rather than degeneration of individual white matter bundles.

The results may offer markers to differentiate PD patients with and without cognitive deficits, according to researchers.

Paper: « Structural Brain Connectome and Cognitive Impairment in Parkinson Disease »
Reprinted from materials provided by the Radiological Society of North America.

People who live close to high-traffic roadways face a higher risk of developing dementia than those who live further away, new research has found.

The study, published in The Lancet, found that people who lived within 50 metres of high-traffic roads had a seven per cent higher likelihood of developing dementia compared to those who lived more than 300 meters away from busy roads.

The researchers examined records of more than 6.5 million Ontario, Canada, residents aged 20-85 to investigate the correlation between living close to major roads and dementia, Parkinson’s disease and multiple sclerosis.

Scientists identified 243,611 cases of dementia, 31,577 cases of Parkinson’s disease, and 9,247 cases of multiple sclerosis in Ontario between 2001 and 2012. In addition, they mapped individuals’ proximity to major roadways using the postal code of their residence. The findings indicate that living close to major roads increased the risk of developing dementia, but not Parkinson’s disease or multiple sclerosis, two other major neurological disorders.

As urban centres become more densely populated and more congested with vehicles on major roads, the researchers suggest the findings of this paper could be used to help inform municipal land use decisions as well as building design to take into account air pollution factors and the impact on residents.

Paper: « Living near major roads and the incidence of dementia, Parkinson’s disease, and multiple sclerosis: a population-based cohort study »
Source: Public Health Ontario