Dementia patients struggle to cope with change because of damage to
general intelligence brain networks
Date:
March 8, 2022
Source:
University of Cambridge
Summary:
People with dementia struggle to adapt to changes in their
environment because of damage to areas of the brain known as
'multiple demand networks', highly-evolved areas of the brain that
support general intelligence, say scientists.
FULL STORY ========================================================================== People with dementia struggle to adapt to changes in their environment
because of damage to areas of the brain known as 'multiple demand
networks', highly- evolved areas of the brain that support general intelligence, say scientists at the University of Cambridge.
========================================================================== There are many different types of dementia, such as Alzheimer's disease
and frontotemporal dementia (FTD), which are characterised by the build-up
of different toxic proteins in different parts of the brain. This means
that the symptoms of dementia vary, and can include problems with memory, speech, behaviour or vision. But one symptom seen across every type of
dementia is a difficulty in responding to unexpected situations.
Dr Thomas Cope from the MRC Cognition and Brain Science Unit and
Department of Clinical Neurosciences at the University of Cambridge said:
"At the heart of all dementias is one core symptom, which is that when
things change or go unexpectedly, people find it very difficult. If
people are in their own environment and everything is going to plan,
then they are OK. But as soon as the kettle's broken or they go somewhere
new, they can find it very hard to deal with." To understand why this
happens, Dr Cope and colleagues analysed data from 75 patients, all of
whom are affected by one of four types of dementia that affect different
areas of the brain. The patients, together with 48 healthy controls,
listened to changing sounds while their brain activity was recorded by a magnetoencephalography machine, which measures the tiny magnetic fields produced by electrical currents in the brain. Unlike traditional MRI
scanners, these machines allow very precise timing of what is happening
in the brain and when. The results of their experiment are published
today in the Journal of Neuroscience.
During the scan, the volunteers watched a silent film -- David
Attenborough's Planet Earth, but without its soundtrack -- while
listening to a series of beeps. The beeps occurred at a steady pattern,
but occasionally a beep would be different, for example a higher pitch
or different volume.
The team found that the unusual beep triggered two responses in the
brain: an immediate response followed by a second response around 200 milliseconds -- a fifth of a second -- a later.
==========================================================================
The initial response came from the basic auditory system, recognising
that it had heard a beep. This response was the same in the patients
and healthy volunteers.
The second response, however, recognised that the beep was unusual. This response was much smaller among the people with dementia than among the
healthy volunteers. In other words, in the healthy controls, the brain
was better at recognising that something had changed.
The researchers looked at which brain areas activated during the task
and how they were connected up, and combined their data with that from
MRI scans, which show the structure of the brain. They showed that damage
to areas of the brain known as 'multiple demand networks' was associated
with a reduction in the later response.
Multiple demand networks, which are found both at the front and rear
of the brain, are areas of the brain that do not have a specific task,
but instead are involved in general intelligence -- for example problems solving. They are highly evolved, found only in humans, primates and more intelligent animals. It is these networks that allow us to be flexible
in our environment.
In the healthy volunteers, the sound is picked up by the auditory system,
which relays information to the multiple demand network to be processed
and interpreted. The network then 'reports back' to the auditory system, instructing it whether to carry on or to attend to the sound.
========================================================================== "There's a lot of controversy about what exactly multiple demand networks
do and how involved they are in our basic perception of the world,"
said Dr Cope.
"There's been an assumption that these intelligence networks work 'above' everything else, doing their own thing and just taking in information. But
what we've shown is no, they're fundamental to how we perceive the world.
"That's why we can look at a picture and immediately pick out the faces
and immediately pick out the relevant information, whereas somebody
with dementia will look at that scene a bit more randomly and won't
immediately pick out what's important." While the research does not
point to any treatments that may alleviate the symptom, it reinforces
advice given to dementia patients and their families, said Dr Cope.
"The advice I give in my clinics is that you can help people who are
affected by dementia by taking a lot more time to signpost changes,
flagging to them that you're going to start talking about something
different or you're going to do something different. And then repeat
yourself more when there's a change, and understand why it's important to
be patient as the brain recognises the new situation." Although their
study only looked at patients with dementia, the findings may explain
similar phenomena experienced by people living with conditions such as schizophrenia, where brain networks can become disrupted.
The research was funded by the Medical Research Council and National
Institute for Health Research, with additional support from Wellcome,
the Biotechnology and Biological Sciences Research Council and the James
S McDonnell Foundation.
Dr Cope is a fellow at Murray Edwards College, Cambridge.
========================================================================== Story Source: Materials provided by University_of_Cambridge. The original
text of this story is licensed under a Creative_Commons_License. Note:
Content may be edited for style and length.
========================================================================== Journal Reference:
1. Thomas E. Cope, Laura E. Hughes, Holly N. Phillips, Natalie
E. Adams,
Amirhossein Jafarian, David Nesbitt, Moataz Assem, Alexandra
Woolgar, John Duncan, James B. Rowe. Causal evidence for
the multiple demand network in change detection: auditory
mismatch magnetoencephalography across focal neurodegenerative
diseases.. The Journal of Neuroscience, 2022; JN-RM-1622-21 DOI:
10.1523/JNEUROSCI.1622-21.2022 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/03/220308130557.htm
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