A recent study conducted by Radiology and led by Dewen Meng, MSc, of the University of Nottingham, England, has identified the contributing cause of cognitive impairment in patients with carotid artery disease (CAD).
Cognitive impairment is the disruption in neural pathway in brain’s white matter, the location and severity of which can be identified by a simple brain MRI.
Meng and colleagues assessed and compared cognitive skills in 108 patients with CAD, out of whom 53 had a cognitive impairment. Cognitive abilities are core skills that your brain uses to carry out tasks, ranging from simplest to most complex. Cognition helps your brain process thoughts and include memory, problem-solving skills and attention.
When the researchers examined brain MRI and cognitive examination skills, they found a clear connection between cognitive impairment and lesions in brain’s white matter. Brain’s MRI was successful in tracking the chronic vascular disease related lacerations in the brain.
MRI, or magnetic resonance imaging, is a radiological test that uses magnetic field and radio waves to snap pictures of your body and brain. MRI is one of the most advanced diagnostic modalities and provides information other radiological techniques, including X-ray, ultrasound and CT scan, cannot provide. The pictures it provides are far clearer and more detailed than those obtained from other imaging methods.
Knowing the potential of this diagnostic method, the researchers from University of Nottingham decided to use it to improve diagnosis of people with a cognitive disorder.
Cognitive disorder is a term that refers to any of the mental disorders that primarily affect your memory, problem solving and reasoning skills. Hallmark diseases of brain and neurons, such as delirium, amnesia and dementia, account for cognitive impairment in majority of the patients.
Vascular cognitive disorders, on the other hand, are caused by a disease of the vessels supplying blood to the brain. A variety of medical conditions such as stroke and transient ischemic attacks can result in vascular cognitive disorders.
When the blood supply to brain is hampered, the affected region begins to lose its healthy tissue resulting in poor memory, and compromised problem, planning and organizing skills.
“If vascular cognitive disorder follows a major stroke, the cognitive impairment typically develops suddenly, and can thus be well recognized,” said study co-author Dewen Meng, MSc, from the University of Nottingham in Nottingham, England. “In the majority of cases such a clear association is lacking, explaining why the detection of vascular cognitive disorder remains challenging.”
The researchers attempted to assess the damage caused by vascular cognitive disorder by using the MRI technique called diffusion tensor imaging. This technique is useful in identifying microscopic brain damage with the help of two measures called mean diffusivity and fractional anisotropy. These techniques can identify even the minutest nerve damage in the brain and measure movement of fluid through tissues.
MRI images could clearly show vascular disease related lesions in brain’s white matter which in turn showed a close correlation with impaired cognitive performance among the subjects. The researchers concluded that vascular cognitive disorders occur when neurons in brain’s cognition center are disconnected and lose communication and information flow in subcortical brain.
This particular MRI technique has turned out to be a promising tool to improve diagnostic accuracy in vascular cognitive disorders. The study was recently published in the journal Radiology.
“This will be a critical step in the quest for prevention of vascular dementia, by helping to identify those at risk, and by enabling imaging studies to evaluate the effectiveness of interventions,” Meng said.
The researchers plan to conduct further studies and track progression of subcortical disconnection to look at changes that may take place in patients over time.