Individuals with Alzheimer’s disease are much more likely to suffer falls compared to other individuals, researchers from Washington University in St. Louis explained at the AAIC 2011 (Alzheimer’s Association® International Conference). Another study, presented at the conference by Australian scientists, explained that retinal imaging may help in the identification of people at risk of Alzheimer’s.

In the first study, researchers measured how often people with and without preclinical Alzheimer’s experienced falls – they were all cognitively healthy individuals. They found that those whose PET scans had higher levels of PiB (an indication of pre-clinical Alzheimer’s) were more than twice as likely to have falls compared to the others.

Among seniors, falls are a major cause of disability, being placed in a nursing home earlier than usual, and injury-related deaths, the presenters explained. It was estimated that the health care costs linked to falls exceeded $19 billion in 2000.

Alzheimer’s impairs a patient’s visual and spatial perception, as well as balance and gait, resulting in a higher risk of falls.

Maria Carrillo, PhD, Alzheimer’s Association Senior Director of Medical and Scientific Relations, said:

“Understanding the traditional hallmarks of Alzheimer’s, including cognitive impairment and memory loss, are important; however, these study results also illustrate the significance of understanding that, in some people, changes in gait and balance may appear before cognitive impairment.

Growing scientific evidence suggests that ‘silent’ biological changes may be occurring in the brain a decade or more before we can see the outward symptoms of Alzheimer’s. According to this study, a fall by an older adult who otherwise has a low risk of falling may signal a need for diagnostic evaluation for Alzheimer’s.”

Susan Stark, PhD. and team monitored 125 seniors for 8 months; they had all undergone PiB PET imaging and had contributed CSF (cerebrospinal fluid) samples. They had enrolled in memory and aging studies at ADRC (Knight Alzheimer’s Disease Research Center). Some of them had preclinical Alzheimer’s while others didn’t.

Each senior was asked to write down in a journal how often they fell. A fall was defined as an accidental movement to the ground, floor or an object below the level of the knee. Data was gathered for an average of 191 days per participant.

A total of 48 participants fell at least once. Those with a positive PiB PET scan result were found to be 2.7 times as likely to experience a fall for each increased unit on their PiB PET scan.

Stark said:

“To our knowledge, this is the first study to identify a risk of increased falls related to a diagnosis of preclinical Alzheimer’s disease. This finding is consistent with previous studies of mobility problems among persons with very early symptomatic Alzheimer’s or mild cognitive impairment. It suggests that higher rates of falls can occur very early in the disease process.”

Carrillo said:

“In the near future, with continued research, we will improve our ability to detect and intervene early in Alzheimer’s disease. With earlier detection, perhaps we can also lower the risk of falls, which can be disabling, expensive and even deadly in older adults. Additional research is urgently needed, for example to further explore the connection between motor deficits and falls as possible early signals of Alzheimer’s.”

Australian researchers wanted to determine whether characteristics of blood vessels in the light-sensitive layer at the back of the eye – the retina – might become useful biomarkers for Alzheimer’s disease.

Shaun Frost, MSc, of CSIRO’s Australian e-Health Research Center explained that studies have shown that Alzheimer’s can cause changes in the eye, and not only the brain. Examining the eye is much easier than the brain.

Frost said:

“Today, there is no single method for detecting Alzheimer’s until the disease is well advanced. Current PET and MRI scans can detect some brain changes, but these procedures can be expensive and technically challenging, and so are impractical for testing in large populations.”

Frost and team looked at retinal images of 136 individuals. 13 of them had Alzheimer’s, 13 mild cognitive impairment and 110 were healthy. The data was gathered from a larger AIBL (Australian Imaging Biomarker and Lifestyle) Flagship Study of Ageing. Various parameters were studied, including retinal blood vessel width.

The scientists found that blood vessel width in the back of the eye was considerably different for those with Alzheimer’s when compared to the healthy individuals. This variation correlated with amyloid plaque deposits in the brain as measured by PET PiB imaging.

Frost said:

“Our studies are very preliminary, but encouraging. Since amyloid plaque build-up in the brain occurs years before cognitive symptoms of Alzheimer’s are evident, a non-invasive and cost-effective retinal test may hold promise as an early detection tool for the disease. We hope that, in the future, our measure could be used with blood-based tests to help doctors identify who needs further assessment with PET imaging and MRI for Alzheimer’s, but more research is needed.”

“Risk of falls among older adults with Preclinical Alzheimer’s Disease”
Susan Stark, PhD, et al.

“Retinal Vascular Parameters as Biomarkers for Alzheimer’s Disease”
Shaun Frost, MSc, et al.

” AAIC 11″

Written by Christian Nordqvist