Featured Research

from universities, journals, and other organizations

Scientists wake up to causes of sleep disruption in Alzheimer's disease

Date:
February 26, 2014
Source:
University of Cambridge
Summary:
New research using fruit flies with Alzheimer's protein finds that the disease doesn't stop the biological clock ticking but detaches it from the sleep-wake cycle that it usually regulates. Findings could lead to more effective ways to improve sleep patterns in those with Alzheimer's.

The fly brain is half a millimeter across and contains approximately 100,000 nerve cells (green). The A-beta peptide forms plaques (red) that are linked to nerve cell death and behavioral abnormalities in the flies.
Credit: Dr. Stanislav Ott, Department of Genetics, University of Cambridge

Being awake at night and dozing during the day can be a distressing early symptom of Alzheimer's disease, but how the disease disrupts our biological clocks to cause these symptoms has remained elusive.

Now, scientists from Cambridge have discovered that in fruit flies with Alzheimer's the biological clock is still ticking but has become uncoupled from the sleep-wake cycle it usually regulates. The findings -- published in Disease Models & Mechanisms -- could help develop more effective ways to improve sleep patterns in people with the disease.

People with Alzheimer's often have poor biological rhythms, something that is a burden for both patients and their carers. Periods of sleep become shorter and more fragmented, resulting in periods of wakefulness at night and snoozing during the day. They can also become restless and agitated in the late afternoon and early evening, something known as 'sundowning'.

Biological clocks go hand in hand with life, and are found in everything from single celled organisms to fruit flies and humans. They are vital because they allow organisms to synchronise their biology to the day-night changes in their environments.

Until now, however, it has been unclear how Alzheimer's disrupts the biological clock. According to Dr Damian Crowther of Cambridge's Department of Genetics, one of the study's authors: "We wanted to know whether people with Alzheimer's disease have a poor behavioural rhythm because they have a clock that's stopped ticking or they have stopped responding to the clock."

The team worked with fruit flies -- a key species for studying Alzheimer's. Evidence suggests that the A-beta peptide, a protein, is behind at least the initial stages of the disease in humans. This has been replicated in fruit flies by introducing the human gene that produces this peptide.

Taking a group of healthy flies and a group with this feature of Alzheimer's, the researchers studied sleep-wake patterns in the flies, and how well their biological clocks were working.

They measured sleep-wake patterns by fitting a small infrared beam, similar to movement sensors in burglar alarms, to the glass tubes housing the flies. When the flies were awake and moving, they broke the beam and these breaks in the beam were counted and recorded.

To study the flies' biological clocks, the researchers attached the protein luciferase -- an enzyme that emits light -- to one of the proteins that forms part of the biological clock. Levels of the protein rise and fall during the night and day, and the glowing protein provided a way of tracing the flies' internal clock.

"This lets us see the brain glowing brighter at night and less during the day, and that's the biological clock shown as a glowing brain. It's beautiful to be able to study first hand in the same organism the molecular working of the clock and the corresponding behaviours," Dr Crowther said.

They found that healthy flies were active during the day and slept at night, whereas those with Alzheimer's sleep and wake randomly. Crucially, however, the diurnal patterns of the luciferase-tagged protein were the same in both healthy and diseased flies, showing that the biological clock still ticks in flies with Alzheimer's.

"Until now, the prevailing view was that Alzheimer's destroyed the biological clock," said Crowther.

"What we have shown in flies with Alzheimer's is that the clock is still ticking but is being ignored by other parts of the brain and body that govern behaviour. If we can understand this, it could help us develop new therapies to tackle sleep disturbances in people with Alzheimer's."

Dr Simon Ridley, Head of Research at Alzheimer's Research UK, who helped to fund the study, said: "Understanding the biology behind distressing symptoms like sleep problems is important to guide the development of new approaches to manage or treat them. This study sheds more light on the how features of Alzheimer's can affect the molecular mechanisms controlling sleep-wake cycles in flies.

"We hope these results can guide further studies in people to ensure that progress is made for the half a million people in the UK with the disease."


Story Source:

The above story is based on materials provided by University of Cambridge. The original story is licensed under a Creative Commons Licence. Note: Materials may be edited for content and length.


Journal Reference:

  1. K.-F. Chen, B. Possidente, D. A. Lomas, D. C. Crowther. The central molecular clock is robust in the face of behavioural arrhythmia in a Drosophila model of Alzheimer's disease. Disease Models & Mechanisms, 2014; DOI: 10.1242/dmm.014134

Cite This Page:

University of Cambridge. "Scientists wake up to causes of sleep disruption in Alzheimer's disease." ScienceDaily. ScienceDaily, 26 February 2014. <www.sciencedaily.com/releases/2014/02/140226211243.htm>.
University of Cambridge. (2014, February 26). Scientists wake up to causes of sleep disruption in Alzheimer's disease. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2014/02/140226211243.htm
University of Cambridge. "Scientists wake up to causes of sleep disruption in Alzheimer's disease." ScienceDaily. www.sciencedaily.com/releases/2014/02/140226211243.htm (accessed July 25, 2014).

Share This




More Health & Medicine News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Beatings and Addiction: Pakistan Drug 'clinic' Tortures Patients

Beatings and Addiction: Pakistan Drug 'clinic' Tortures Patients

AFP (July 24, 2014) — A so-called drugs rehab 'clinic' is closed down in Pakistan after police find scores of ‘patients’ chained up alleging serial abuse. Duration 03:05 Video provided by AFP
Powered by NewsLook.com
Too Few Teens Receiving HPV Vaccination, CDC Says

Too Few Teens Receiving HPV Vaccination, CDC Says

Newsy (July 24, 2014) — The Centers for Disease Control and Prevention is blaming doctors for the low number of children being vaccinated for HPV. Video provided by Newsy
Powered by NewsLook.com
New Painkiller Designed To Discourage Abuse: Will It Work?

New Painkiller Designed To Discourage Abuse: Will It Work?

Newsy (July 24, 2014) — The FDA approved Targiniq ER on Wednesday, a painkiller designed to keep users from abusing it. Like any new medication, however, it has doubters. Video provided by Newsy
Powered by NewsLook.com
Doctor At Forefront Of Fighting Ebola Outbreak Gets Ebola

Doctor At Forefront Of Fighting Ebola Outbreak Gets Ebola

Newsy (July 24, 2014) — Sheik Umar Khan has treated many of the people infected in the Ebola outbreak, and now he's become one of them. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:  

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile iPhone Android Web
          Follow Facebook Twitter Google+
          Subscribe RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins