New research published in The Journal of Neuroscience provides evidence that people who are cognitively frail are not in the initial stages of dementia. Instead, cognitive frailty is a sign of poor-quality normal ageing brought on by factors such as lower socioeconomic status, education level and risk factors related to their health and lifestyle.
Cognitive frailty in this instance refers to people with reduced cognitive function who don’t experience memory loss or have a diagnosis of dementia or its precursor, mild cognitive impairment (MCI). To learn more, read our blog post ‘What is cognition?’
The study was conducted by a team from the University of Cambridge led by Dr Ece Kocagoncu, who is funded by DPUK. Dr Kocagoncu works in the Cambridge Centre for Frontotemporal Dementia under the supervision of Professor James Rowe, an Associate Director of DPUK.
Dr Kocagoncu said: ‘Although people with cognitive frailty perform similarly to people with MCI in cognitive tests, their brains don’t show the features associated with MCI or Alzheimer’s disease. In fact, their brains are far more similar to those of neurologically healthy control subjects.’
All these people are participants of a project called The Cambridge Centre for Ageing and Neuroscience (Cam-CAN), whose data Dr Kocagoncu’s team analysed. As part of Cam-CAN the subjects completed a series of tests (called cognitive tests) to measure their thinking skills. They also had several types of brain scan: MRI scans to reveal the structure of their brains, and MEG and EEG scans to measure their brain cell activity while doing tasks.
One of these tests was called the ‘cross-modal oddball task’, in which an abstract image is paired with a sound. Sometimes, the researchers played either a new sound or a sound that had previously been paired with a different image. Dr Kocagoncu said: ‘This is a good test of Alzheimer’s because to recognise that something is novel, you have to remember what it was like before.’
Those with MCI, Alzheimer’s disease and cognitive frailty scored lower in the cognitive tests than the control participants, who had healthy brains. However, the brain scans divulged that the cognitively frail were more physiologically similar to the healthy controls than the participants with MCI or Alzheimer’s disease.
The structural MRI revealed that people with MCI and Alzheimer’s disease had smaller volumes in their temporal cortices and hippocampi – two areas of the brain responsible for memory – than the controls or those with cognitive frailty. To read more about the roles of different brain areas, read our blog post ‘Brain areas decoded’.
In addition, people with MCI and Alzheimer’s disease had lower brain cell activity when presented with mismatched pairs of images and sounds compared with the control and cognitively frail participants.
Dr Kocagoncu said: ‘Our research shows that both cognitive tests and biological markers are needed to confirm someone has Alzheimer’s disease, but we often see GPs diagnosing people with dementia based only on cognitive tests. There are specialised memory clinics all around the UK, with expert clinicians who are well equipped to perform in-depth dementia screenings and test for alternative explanations of the cognitive complaint. We need to make the use of brain scans and tests to detect Alzheimer’s-related proteins more common to prevent false diagnoses of dementia.’