Nav: Home

Dementia: New insights into causes of loss of orientation

January 12, 2016

New research has revealed how disease-associated changes in two interlinked networks within the brain may play a key role in the development of the symptoms of dementia.

The University of Exeter Medical School led two studies, each of which moves us a step closer to understanding the onset of dementia, and potentially to paving the way for future therapies. Both studies, part-funded by Alzheimer's Research UK, are published in the Journal of Neuroscience and involved collaboration with the University of Bristol.

Both studies shed light on how two parts of the brain's 'GPS' navigation system malfunctions in dementia, and point to likely underpinning causes for loss of orientation that is commonly experienced by people living with the condition.

In the first study, the team studied a part of the brain called the entorhinal cortex. Located near the base of the brain, this region is associated with functions including memory formation and navigation, and contains so-called "grid cells". These nerve cells fire electrical discharges in a grid-like pattern, much like the grid on an Ordnance Survey map. Paralleling the different scales employed by different maps, the grid firing patterns in the entorhinal cortex also have different scales, with cells at the top of the cortex having a more tightly packed grid pattern than those at the bottom. Scientists believe that this top-to-bottom gradient of different grid scales contributes pivotally to our sense of spatial location.

The team compared the activity in the entorhinal cortex of healthy mice and mice with dementia. They found that top-to-bottom gradients in electrical activity in the entorhinal cortex are not present in mice with dementia. Their findings suggest that the fine navigational detail, such as you would find on a large-scale map, is not correctly represented in patients with dementia.

Dr Jon Brown at the University of Exeter Medical School led the studies, as part of his Alzheimer's Research UK Senior Fellowship. He said: "This is an exciting discovery because it is the first time grid cell activity has been linked to the onset of disease. We now need further research to better establish how these findings translate to dementia in humans."

In the second study, researchers examined "place cells" located in the hippocampus, a brain structure known to be critical in processing learning and memory, both affected by dementia. Place cells help us to identify where we are within a certain space.

The team found that the hippocampus of mice with dementia was associated with specific disturbances in synaptic, cellular, and network-level function, meaning that spatial information was wrongly encoded and spatial memory was impaired.

Dr Brown said: "Dementia is one of the greatest health challenges of our time, and we still have so much to learn about its causes, as well as about how our brains work. This research makes progress in both areas, and is another small step along the road to earlier diagnoses and finding new treatments and therapies."

Professor Andrew Randall, who co-supervised much of the work, said: "This has been a fascinating experimental journey for our research teams, and much of the pivotal work was carried out by talented PhD students. We look forward to producing much more work of this nature as members of Exeter's growing dementia research community."

Dr Laura Phipps from Alzheimer's Research UK, said: "There are 850,000 people in the UK with dementia and a tenth of those are living in the South West. It is vital that researchers explore the complexities of the brain, to understand more about the causes of the condition and how we can tackle it. Dementia is not just a synonym for forgetfulness - these findings in mice highlight the impact that diseases like Alzheimer's can have on spatial orientation. It will now be important to build on this research, to understand whether this chain of events can be targeted in the hunt for new treatments."

The University of Exeter forms part of the Alzheimer's Research UK South West Research Network - a community of dementia researchers in Exeter and Plymouth, working collaboratively to accelerate progress in dementia research.
-end-


University of Exeter

Related Dementia Articles:

Digital solutions for dementia care
Telehealth delivery of dementia care in the home can be as effective as face-to-face home visit services if carers and recipients take advantage of the technologies available, Australian researchers say.
Despite a marked reduction in the prevalence of dementia, the number of people with dementia is set to double by 2050 according to new Alzheimer Europe report
Today, at a European Parliament lunch debate, Alzheimer Europe launched a new report presenting the findings of its collaborative analysis of recent prevalence studies and setting out updated prevalence rates for dementia in Europe.
Inflammatory marker linked to dementia
Higher levels of an inflammatory marker, sCD14, were associated with brain atrophy, cognitive decline and dementia in two large heart studies.
How likely do you think you are to develop dementia?
A poll suggests almost half of adults ages 50 to 64 believe they're likely to develop dementia.
Latest issue of Alzheimer's & Dementia
Predicting heart disease might also be a warning sign for Alzheimer's; A new way to think about the environment and Alzheimer's research; Most dementia patients don't receive care from physicians who specialize in brain health.
What multilingual nuns can tell us about dementia
A strong ability in languages may help reduce the risk of developing dementia, says a new University of Waterloo study.
Brain changes may help track dementia, even before diagnosis
Even before a dementia diagnosis, people with mild cognitive impairment may have different changes in the brain depending on what type of dementia they have, according to a study published in the September 11, 2019, online issue of Neurology®, the medical journal of the American Academy of Neurology.
Could marriage stave off dementia?
Dementia and marital status could be linked, according to a new Michigan State University study that found married people are less likely to experience dementia as they age.
Migraine diagnoses positively associated with all-cause dementia
Several studies have recently focused on the association between migraine headaches and other headaches and dementia and found a positive migraine-dementia relationship.
Apathy: The forgotten symptom of dementia
Apathy is the most common neuropsychiatric symptom of dementia, with a bigger impact on function than memory loss -- yet it is under-researched and often forgotten in care.
More Dementia News and Dementia Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Making Amends
What makes a true apology? What does it mean to make amends for past mistakes? This hour, TED speakers explore how repairing the wrongs of the past is the first step toward healing for the future. Guests include historian and preservationist Brent Leggs, law professor Martha Minow, librarian Dawn Wacek, and playwright V (formerly Eve Ensler).
Now Playing: Science for the People

#566 Is Your Gut Leaking?
This week we're busting the human gut wide open with Dr. Alessio Fasano from the Center for Celiac Research and Treatment at Massachusetts General Hospital. Join host Anika Hazra for our discussion separating fact from fiction on the controversial topic of leaky gut syndrome. We cover everything from what causes a leaky gut to interpreting the results of a gut microbiome test! Related links: Center for Celiac Research and Treatment website and their YouTube channel
Now Playing: Radiolab

The Third. A TED Talk.
Jad gives a TED talk about his life as a journalist and how Radiolab has evolved over the years. Here's how TED described it:How do you end a story? Host of Radiolab Jad Abumrad tells how his search for an answer led him home to the mountains of Tennessee, where he met an unexpected teacher: Dolly Parton.Jad Nicholas Abumrad is a Lebanese-American radio host, composer and producer. He is the founder of the syndicated public radio program Radiolab, which is broadcast on over 600 radio stations nationwide and is downloaded more than 120 million times a year as a podcast. He also created More Perfect, a podcast that tells the stories behind the Supreme Court's most famous decisions. And most recently, Dolly Parton's America, a nine-episode podcast exploring the life and times of the iconic country music star. Abumrad has received three Peabody Awards and was named a MacArthur Fellow in 2011.