Sunlight exposure and latitude linked to development of dystonia symptoms

June 5, 2015 by Thomas Deane, Trinity College Dublin
Cloud in Nepali sky. Credit: Wikipedia

People with a genetic predisposition to dystonia living closer to the equator (and who are thus exposed to more sunlight) are more likely to develop involuntary contraction of their eye muscles (blepharospasm) than those in their necks.

Dystonia is one of many neurological disorders that manifests itself in a variety of ways, but now a collaborative research team has shown that sun exposure drives one of the different manifestations of the condition that often leaves those affected feeling socially isolated and marginalised.

Dystonia is the third-most common movement disorder, affecting up to 3,000 people in Ireland. The disorder may present in different ways, ranging from writer's cramp to involuntary head rotations and to the involuntary eyelid closure known as blepharospasm. Scientists believe that abnormal signalling from areas deep in the brain results in abnormal, overactivity of muscles.

Botulinum toxin (Botox) injections are typically given to treat the of the disorder and while this can be somewhat effective, the injections need to be repeated once every three to four months. Further to the physical symptoms, people with Dystonia feel socially isolated, so there is thus a great need to better understand the different types of .

In a recent research study entitled 'Sun exposure is an environmental factor for the development of blepharospasm', published in the international peer-reviewed Journal of Neurology, Neurosurgery & Psychiatry, a collaborative research team from Trinity College Dublin, UCD and St Vincent's Hospital has found that sunlight exposure for people genetically predisposed to dystonia, and living closer to the equator, is a key driver in the development of involuntary eye closure (blepharospasm).

Speaking about the study, first author Dr Anna Molloy, Neurology Registrar at St. Vincent's University Hospital, said: "We looked at 15 different studies that reported the relative prevalence of involuntary eyelid closure (blepharospasm) and a type of involuntary neck movement (called ) in people living at various latitudes from Reykjavik in Iceland to Kolkata in India. For each of the locations we took solar insolation information from the US national Aeronautics and Space Administration (NASA) Surface and Meteorology and Solar Energy (SSE) database. What we see is a significant pattern, whereby the people living closer to the equator, and exposed to more sunlight, are much more likely to develop blepharospasm than cervical dystonia."

Co-author, Research Professor of Neural Engineering at Trinity, Richard Reilly, added: "This finding further supports our previously published work investigating the role of environmental factors in the manifestation of adult-onset dystonia."

Senior author, Professor Michael Hutchinson, St. Vincent's University Hospital and University College Dublin, concluded: "This further supports evidence for the interaction between genetics and environmental factors in the development of the adult onset focal dystonia."

Explore further: Scientists identify new protein in the neurological disorder dystonia

More information: "Sun exposure is an environmental factor for the development of blepharospasm." J Neurol Neurosurg Psychiatry jnnp-2014-310266Published Online First: 22 April 2015 DOI: 10.1136/jnnp-2014-310266

Related Stories

Scientists identify new protein in the neurological disorder dystonia

May 6, 2014
A collaborative discovery involving Kansas State University researchers may lead to the first universal treatment for dystonia, a neurological disorder that affects nearly half a million Americans.

Researchers ID gene behind primary cervical dystonia, a neck-twisting disorder

March 5, 2012
Researchers have identified a gene that causes adult-onset primary cervical dystonia, an often-painful condition in which patients' necks twist involuntarily. The discovery by a team from the Jacksonville, Fla., campus of ...

Team aids discovery of first dystonia gene found in African-Americans

March 7, 2013
A pair of studies tells the tale of how a neuroscientist at Mayo Clinic in Florida helped to discover the first African-American family to have inherited the rare movement disorder dystonia, which causes repetitive muscle ...

Recommended for you

People are more honest when using a foreign tongue, research finds

August 17, 2018
New UChicago-led research suggests that someone who speaks in a foreign language is probably more credible than the average native speaker.

FDA approves brain stimulation device for OCD

August 17, 2018
(HealthDay)—A brain stimulation device to treat obsessive-compulsive disorder (OCD) has received approval for marketing Friday by the U.S. Food and Drug Administration.

Research eyes role of stress in mental illnesses

August 17, 2018
We all face stress in our lives. Even researchers seeking to understand why some people shrug it off while others face battles against disorders like depression or PTSD.

16 going on 66: Will you be the same person 50 years from now?

August 17, 2018
How much do you change between high school and retirement? The answer depends on whether you're comparing yourself to others or to your younger self.

Men and women show surprising differences in seeing motion

August 16, 2018
Researchers reporting in the journal Current Biology on August 16 have found an unexpected difference between men and women. On average, their studies show, men pick up on visual motion significantly faster than women do.

It's okay when you're not okay: Study re-evaluates resilience in adults

August 16, 2018
Adversity is part of life: Loved ones die. Soldiers deploy to war. Patients receive terminal diagnoses.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.