A group of United States-based researchers has discovered a direct correlation with functional cell loss in the retina and signs of dementia in people with a genetic risk for fronto-temporal dementia (FTD).
The study also demonstrates that changes in the retina occur much earlier than do the dementia-related changes that appear in an individual’s behavior.
The Journal of Experimental Medicine
This cutting-edge eye/brain research was published in the September 2014 issue of The Journal of Experimental Medicine. Since its inception in 1896 at the Johns Hopkins School of Medicine, The Journal of Experimental Medicine has published papers on the physiological, pathological, and molecular aspects of disease. The journal is also committed to publishing studies that involve human subjects. You can read more about the journal’s history on its Wikipedia page.
The authors are Michael E. Ward, Alice Taubes, Robert Chen, Bruce L. Miller Chantelle F. Sephton, Jeffrey M. Gelfand, Sakura Minami; John Boscardin, Lauren Herl Martens, William W. Seeley, Gang Yu, Joachim Herz, Anthony J. Filiano, Andrew E. Arrant, Erik D. Roberson, Timothy W. Kraft, Robert V. Farese Jr., Ari Green, and Li Gan, who represent the following institutions: University of California, San Francisco; University of Texas Southwestern Medical Center, Dallas; and the University of Alabama at Birmingham.
What is Fronto-Temporal Dementia?
Excerpted from Frontotemporal Dementia at the Alzheimer’s Association website:
Frontotemporal dementia (FTD) is a group of disorders caused by progressive cell degeneration in the brain’s frontal lobes (the areas behind your forehead) or its temporal lobes (the regions behind your ears).
The cell damage caused by frontotemporal dementia leads to tissue shrinkage and reduced function in the brain’s frontal and temporal lobes, which control planning and judgment; emotions, speaking and understanding speech; and certain types of movement.
FTD used to be called Pick’s disease after Arnold Pick, a physician who in 1892 first described a patient with distinct symptoms affecting language. Some doctors still use the term “Pick’s disease.” FTD was once considered rare, but it’s now thought to account for up to 10 to 15 percent of all dementia cases.
There is no single test — or any combination of tests — that can conclusively diagnose frontotemporal dementia. FTD is a “clinical” diagnosis representing a doctor’s best professional judgment about the reason for a person’s symptoms. Magnetic resonance imaging (MRI) often plays a key role in diagnosis because it can detect shrinkage in the brain’s frontal and temporal lobes, which is a hallmark of FTD.
In some cases, it may be hard to distinguish FTD from Alzheimer’s disease. In the future, tests to detect specific protein abnormalities linked to Alzheimer’s and FTD may help clarify the diagnosis in difficult cases. Most people with FTD are diagnosed in their 50s and early 60s. Only about 10 percent are diagnosed after age 70. Alzheimer’s, on the other hand, grows more common with increasing age.
More about the Research
Changes in the eye might predict onset of frontotemporal dementia, via the University of Alabama at Birmingham (UAB) School of Medicine News:
Changes to the eyes might help diagnose the onset of frontotemporal dementia (FTD), the second most common form of dementia, according to new research from scientists at the University of Alabama at Birmingham, Gladstone Institutes, and the University of California, San Francisco. Findings … show that a loss of cells in the retina is one of the earliest signs of FTD in people with a genetic risk for the disorder – even before any changes appear in their behavior.
The researchers 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 [co-author] Erik Roberson. 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,” he said. “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.
[Editor’s note: The researchers used an electroretinogram (ERG) as the measuring device in their subjects. An ERG is an “electrocardiogram (EKG) for the eye” that measures the electrical signal activity of ganglion cells, a type of neuron located near the inner surface of the retina. Ganglion cells transmit image-forming and non-image forming visual information to the brain.
The researchers compared ganglion cell activity in healthy subjects with subjects known to have frontotemporal dementia, noting a significant decrease in cell activity in the retina of subjects with dementia.]
“We have a more complete understanding about how the retina functions as opposed to the operations of the complex brain,” said [co-author] Timothy Kraft. “That makes it much easier to use the retina as a tool for better understanding FTD.”
“The results of this study have shown that we can use the thinning of retinal cells as a marker for this type of dementia,” said Roberson. “Further studies may also help determine whether the changes in the retina can be utilized as a marker of disease progression. We may also be able to use the retina as a means of gauging the effectiveness of new therapies.”
VisionAware will continue to report the results of this innovative dementia research as they become available.