Research finds that vascular brain injury is an important risk factor in cognitive impairment
Cognitive impairment – problems with day-to-day memory, language, planning or attention – affects between 5% and 20% of people aged 75 and over, depending on the method by which patients are diagnosed.
And, while cognitive impairment may be mild and could even be the result of stress or depression, rather than dementia, around 15% of people with mild cognitive impairment will go on to develop dementia.
Now new research has found that vascular brain injury via stroke or high blood pressure, for example, is more significant for predicting cognitive impairment than amyloid plaques, a factor strongly linked with forms of dementia such as Alzheimer’s.
Researchers from the UC Davis Alzheimer’s Disease Research Centre, USA, looked at how vascular brain injury is linked to the build-up of amyloid plaques, as well as what effect each factor – vascular brain injury and amyloid plaques – has on memory and executive functioning.
Previous research with animals suggested that it could be possible that a vascular brain injury, via stroke, for example, could increase the risk of amyloid plaques, thereby linking the two factors but, according to this new research, the two aren’t linked in this way – at least not in humans.
“If that were the case, people who had more vascular brain injury should have higher levels of beta amyloid,” said Bruce Reed, associate director of US Davis Alzheimer’s Disease Research Centre. “We found no evidence to support that.”
The researchers assessed study participants using magnetic resonance imaging to assess vascular brain injury and positron emission tomography (PET) to check for beta amyloid build-up. Infarcts, the result of vascular brain injury, were common and, even in patients where they were ‘clinically silent’ (ie they hadn’t been previously diagnosed or caused significant or noticeable problems), they were correlated with impaired thinking. Vascular brain injury occurs when inadequate blood flow reaches the brain, so it could be caused by a stroke, high blood pressure, or a head injury, for example.
The other previously held assumption was that amyloid plaques would have a greater impact on the prevalence of cognitive function than vascular brain injuries, but again, the researchers found no evidence to support this. In fact, they found the reverse was true. While patients with vascular brain injury showed significant risk of developing cognitive impairment, patients with abnormal levels of amyloid did not.
“The more vascular brain injury the participants had, the worse their memory and the worse their executive function – their ability to organise and problem solve,” said Reed.
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