Neurodegenerative changes occur decades before a reduced cognitive ability becomes apparent. These changes can be detected but the procedures are expensive or invasive and are not suitable for large-scale early warning programmes. Now, Empa researchers are working with partners from the Cantonal Hospital and the Geriatric Clinic in St. Gallen, all in Switzerland, on a non-invasive diagnostic method that detects the early processes of dementia.
Patrick Eggenberger and Simon Annaheim from Empa's Biomimetic Membranes and Textiles lab in St. Gallen are using a sensor belt - already used for ECG measurements - equipped with sensors for other relevant parameters such as body temperature and gait pattern. According to the team, subtle changes that appear are expressed through unconscious bodily reactions, and these changes can only be recorded precisely when measurements are taken over a longer period of time.
"It should be possible to integrate the long-term measurements into everyday life," said Annaheim.
Skin-friendly and comfortable monitoring systems are essential for measurements that are suitable for everyday use, and to this end the belt will be based on flexible sensors with electrically conductive or light-conducting fibres, plus sensors for motion and temperature measurement.
To enable such long-term measurements the researchers are integrating the collected data into mathematical models developed at Empa, the Swiss Federal Laboratories for Materials Science and Technology.
The goal is an an early warning system that can estimate the progression of cognitive impairment. Another advantage is that the data measurements can be integrated into telemonitoring solutions and can improve patient care in familiar environments.
A key indicator of the onset of dementia is body temperature, which remains constant in a range of 1oC.
According to Empa, the values naturally oscillate in the course of the day. This daily rhythm changes with age and is conspicuous in neurodegenerative diseases such as dementia or Parkinson's disease. In Alzheimer's patients, the core body temperature is elevated by up to 0.2oC. At the same time, the spikes in daily temperature fluctuations are dampened.
In a study, the researchers have shown that altered skin temperature readings measured with the sensor belt provide an indication of the cognitive performance of test subjects, and can do so well before dementia develops.
The test subjects in the study included healthy people with or without mild brain impairment. This mild cognitive impairment (MCI) does not represent a disability in everyday life, but it is considered a possible precursor to Alzheimer's disease.
The subjects took part in long-term measurements and neuropsychological tests and it was found that a lower body temperature, which fluctuated more throughout the day, was linked to a better cognitive performance. In individuals with MCI, body temperature varied less and was slightly elevated overall.
The researchers looked also at heart health as an indicator of the onset of neurodegeneration. The heartbeat is subject to natural variations that show how the nervous system adapts to sudden challenges. The small pause between two heartbeats, about one second in duration, has significance for health because there may be problems with the nervous system when the pause always remains the same.
A study by researchers from ETH Zurich determined that poorer measurements in older, healthy people can be improved within six months through cognitive-motor dance training. In these "exergames," the test subjects imitated sequences of steps from a video. In contrast, participants who instead only trained in straight lines on a treadmill, but also trained their memory, benefited less.
"The point is to intervene early with appropriate training as soon as the first negative signs can be measured," said Eggenberger. "With our sensor system, any improvements in cognitive performance can be tracked through movement-based forms of therapy."
Studies with long-term monitoring will now be used to clarify how the sensor measurements can be used to predict the progression of mild brain disorders.