CHANGES IN EYE CAN PREDICT CHANGES IN BRAIN

Researchers at the Gladstone Institutes and University of California, San Francisco have shown that a loss of cells in the retina is one of the earliest signs of frontotemporal dementia (FTD) in people with a genetic risk for the disorder -- even before any changes appear in their behavior.

Published in the Journal of Experimental Medicine, the researchers, led by Gladstone investigator Li Gan, PhD and UCSF associate professor of neurology Ari Green, MD, studied a group of individuals who had a certain genetic mutation that is known to result in FTD. They discovered that before any cognitive signs of dementia were present, these individuals showed a significant thinning of the retina compared with people who did not have the gene mutation.

"This finding suggests that the retina acts as a type of 'window to the brain,'" said Dr. Gan. "Retinal degeneration was detectable in mutation carriers prior to the onset of cognitive symptoms, establishing retinal thinning as one of the earliest observable signs of familial FTD. This means that retinal thinning could be an easily measured outcome for clinical trials."

Although it is located in the eye, the retina is made up of neurons with direct connections to the brain. This means that studying the retina is one of the easiest and most accessible ways to examine and track changes in neurons.

Lead author Michael Ward, MD, PhD, a postdoctoral fellow at the Gladstone Institutes and assistant professor of neurology at UCSF, explained, "The retina may be used as a model to study the development of FTD in neurons. If we follow these patients over time, we may be able to correlate a decline in retinal thickness with disease progression. In addition, we may be able to track the effectiveness of a treatment through a simple eye examination."

The researchers also discovered new mechanisms by which cell death occurs in FTD. As with most complex neurological disorders, there are several changes in the brain that contribute to the development of FTD. In the inherited form researched in the current study, this includes a deficiency of the protein progranulin, which is tied to the mislocalization of another crucial protein, TDP-43, from the nucleus of the cell out to the cytoplasm.

However, the relationship between neurodegeneration, progranulin, and TDP-43 was previously unclear. In follow-up studies using a genetic mouse model of FTD, the scientists were able to investigate this connection for the first time in neurons from the retina. They identified a depletion of TDP-43 from the cell nuclei before any signs of neurodegeneration occurred, signifying that this loss may be a direct cause of the cell death associated with FTD.

TDP-43 levels were shown to be regulated by a third cellular protein called Ran. By increasing expression of Ran, the researchers were able to elevate TDP-43 levels in the nucleus of progranulin-deficient neurons and prevent their death.

"With these findings," said Dr. Gan, "we now not only know that retinal thinning can act as a pre-symptomatic marker of dementia, but we've also gained an understanding into the underlying mechanisms of frontotemporal dementia that could potentially lead to novel therapeutic targets."

JUDGEMENT DECISIONS MORE THAN MEETS THE EYE

People make immediate judgments about images they are shown, which could impact on their decisions, even before their brains have had time to consciously process the information, a study of brainwaves led by The University Of Melbourne has found.

Published in PLOS ONE, the study is the first in the world to show that it is possible to predict abstract judgments from brain waves, even though people were not conscious of making such judgments. The study also increases our understanding of impulsive behaviors and how to regulate it.

It found that researchers could predict from participants' brain activity how exciting they found a particular image to be, and whether a particular image made them think more about the future or the present. This is true even though the brain activity was recorded before participants knew they were going to be asked to make these judgments.

Lead authors Dr Stefan Bode from the Melbourne School of Psychological Sciences and Dr Carsten Murawski from the University of Melbourne Department of Finance said these findings illustrated there was more information encoded in brain activity than previously assumed.

"We have found that brain activity when looking at images can encode judgments such as time reference, even when the viewer is not aware of making such judgments. Moreover, our results suggest that certain images can prompt a person to think about the present or the future," they said.

The authors said the results contributed to our understanding of impulsive behaviors, especially where those behaviors were caused by 'prompts' in the world around us.

"For instance, consider someone trying to quit gambling who sees a gambling advertisement on TV. Our results suggest that even if this person is trying to ignore the ad, their brain may be unconsciously processing it and making it more likely that they will relapse," he said.

The researchers used electroencephalography technology (EEG) to measure the electrical activity of people's brains while they looked at different pictures. The pictures displayed images of food, social scenes or status symbols like cars and money.

After the EEG, researchers showed participants the same pictures again and asked questions about each image, such as how exciting they thought the image was or how strongly the image made them think of either the present or the future.

A statistical 'decoding' technique was then used to predict the judgments participants made about each of the pictures from the EEG brain activity that was recorded.

Co-author Daniel Bennett said just as certain prompts might cause impulsive behavior, images could be used to prompt people to be more patient by regulating impulse control.

"Our results suggest that prompting people with images related to the future might cause processing outside awareness that could make it easier to think about the future. In theory, this could make people less impulsive and more likely to make healthy long-term decisions. These are hypotheses we will try to test in the future," he said. The research was done in collaboration with the University of Cologne, Germany.

WEAR SUN GLASSES TO PREVENT COMMON EYE DISEASES

If your job leads to spending most of the time outdoors, do not forget to wear sunglasses as it can save you from developing a common eye disease.

According to a study, residential geography, time spent in the sun and whether or not sunglasses are worn may help explain why some people develop exfoliation syndrome (XFS), an eye condition that is a leading cause of secondary open-angle glaucoma and can lead to an increased risk of cataract.

“Lifetime outdoor activities may contribute to XFS so a more widespread use of UV-blocking eyewear can help prevent XFS,” said lead study author Louis Pasquale, as associate professor of ophthalmology at Harvard Medical School (HMS).

Researchers conducted a clinic-based, case-control study in the US and Israel, involving XFS cases and control individuals.

They measured weighted lifetime average latitude of residence and average number of hours per week spent outdoors as determined by validated questionnaires.

They found that genetic or environmental factors also contribute to XFS.

Previous studies have shown that residential (geographic) history and extent of solar exposure may be important risk factors for XFS.

The study appeared in the journal Ophthalmology.