Artist’s rendition of astronauts on Mars. (NASA)

Traveling into deep space could accelerate the onset of Alzheimer’s disease, an incurable form of dementia, according to a new report.

The NASA-funded study assessed how cosmic radiation would impact the astronauts throughout their trip in deep space. The effect of cosmic radiation on the human body has been a  concern for the US space agency as it plans manned missions into deep space, such as one to a distant asteroid in 2021, and another to Mars in 2035.

Earth’s magnetic field usually keeps us, and those in low Earth orbit, safe from the perils of cosmic radiation. However, beyond Earth’s protective magnetic fields, space travelers are exposed to a constant barrage of radiation.

With adequate warning, such as in the case of solar flares, steps can be taken to protect astronauts from dangerous forms of radiation. However, other forms of cosmic radiation, which occur without warning, cannot be blocked as effectively.

“Galactic cosmic radiation poses a significant threat to future astronauts,” said M. Kerry O’Banion,  a professor in the University of Rochester Medical Center (URMC) and senior author of the study. “The possibility that radiation exposure in space may give rise to health problems such as cancer has long been recognized. However, this study shows for the first time that exposure to radiation levels equivalent to a mission to Mars could produce cognitive problems and speed up changes in the brain that are associated with Alzheimer’s disease.”

Artist’s illustration of the shape and function of the Earth’s magnetic field that protects us from harmful cosmic radiation (NASA)

In the past,  scientists studied the impact of cosmic radiation on a living being’s cardiovascular and musculoskeletal systems, as well as potential risks of contracting various forms of cancer.But the new study,  published in  PLOS ONE, examined the possible effects of space radiation on neurodegeneration, a gradual loss of brain structure or function.

For this study, researchers wanted to find out what role, if any, cosmic radiation plays in accelerating the biological and cognitive indicators of Alzheimer’s disease, especially in those  predisposed to developing the illness.

They specifically wanted to learn more about the impact of radiation from high-mass, high-charged (HZE) particles, which come in many forms and travel through space with the force of exploding stars.

Instead of examining hydrogen protons, which are produced by solar flares, the researchers decided to study iron particles. They say HZE particles, such as iron, when combined with their high rate of speed, are able to go through solid objects, like a spacecraft’s walls and protective shielding.

“Because iron particles pack a bigger wallop, it is extremely difficult, from an engineering perspective, to effectively shield against them,” said O’Banion. “One would have to essentially wrap a spacecraft in a six-foot block of lead or concrete.”

Brain affected by Alzheimer’s Disease (left) vs normal brain (right) – (US Dept of Veterans Affairs)

The researchers exposed mice to various doses of radiation, including levels that would be similar to what astronauts would experience during deep space voyages.To evaluate the cognitive and biological impact of the radiation exposure, the mice were then put through a series of experiments in which they had to recall objects or specific locations. Researchers observed that the radiation- exposed mice were much more likely to fail these tests, suggesting neurological impairment, earlier than the symptoms would typically appear.

Along with symptoms of neurological damage, the researchers found that the mice’s brains also showed signs of vascular changes and had a greater than usual buildup of beta amyloid, the protein “plaque” that gathers in the brain and is one of the characteristics of Alzheimer’s Disease.

“These findings clearly suggest that exposure to radiation in space has the potential to accelerate the development of Alzheimer’s disease,” said O’Banion. “This is yet another factor that NASA, which is clearly concerned about the health risks to its astronauts, will need to take into account as it plans future missions.”

(Photo: Nicolas Holzheu via Flickr/Creative Commons)

People can tell how old you are by how you smell, according to new research published in the journal PLoS One.

It appears that “old person smell” some people complain about is for real, that elderly people emit a unique identifying odor.

An elderly individual’s “old person smell”  is actually acknowledged and accepted in cultures throughout the world.  In Japan, there’s a special word, kareishū,  that describes it.

Funny thing though, according to the research, all age groups rated “old person smell” as less intense and less unpleasant than the body odors of middle-aged and young individuals.

Our sense of smell, coupled with our unique body odor, provides us with a very powerful and effective method of non-verbal communication.

The body odors of other, non-human animals, hold a wide assortment of a number of chemical components that can communicate a wide variety of social information.  Scientists say that the intensities of the chemical behind those odors and how they are perceived by others tend to change throughout a person’s life.

“Similar to other animals, humans can extract signals from body odors that allow us to identify biological age, avoid sick individuals, pick a suitable partner and distinguish kin from non-kin,” said Johan Lundström, senior report author, who is a sensory neuroscientist at the Monell Chemical Senses Center in Philadelphia, Penn.

Scientists have theories regarding how these age-related odors relate to mating and how they help animals choose their suitable mates.  For example, certain scents might suggest that older males are more desirable because they contribute genes that allow offspring to live longer, while older females might be avoided because their reproductive systems are more fragile.

In conducting the research for the study, scientists collected samples of body odor from people in three age groups. Those between 20 and 30 years old were considered to be the young group, those 45 to 55 were the middle-age group and the old age group was made up with people between 75 and 95 years-old, with 12 to 16 people per group.

Each test subject slept in an unscented t-shirt that contained underarm pads for five nights.  These pads where then cut into four pieces and placed into separate glass jars.

A group of 41 young (20 to 30 years old) people served as evaluators and were each given two of the test jars in nine combinations and were asked to identify which of the samples came from older people and evaluate the odors based on  intensity and how pleasant each one was.   These young evaluators were then asked to give an estimate as to the age of the donor of each sample.

The evaluators were able to differentiate people in each of the three donor age groups based strictly on odor.  Odors from the old-age group drove the evaluator’s ability to discern age.  The researcher also said that they found that the young evaluators rated the old-age body odors as being less intense and not as unpleasant as the odors from the young and middle-age groups.

“Elderly people have a discernible underarm odor that younger people consider to be fairly neutral and not very unpleasant,” said Lundström. “This was surprising given the popular conception of old age odor as disagreeable. However, it is possible that other sources of body odors, such as skin or breath, may have different qualities.”

In future studies, the researchers will try to identify the primary biomarkers that evaluators use to identify age-related odors and to determine how the brain is able to identify and measure this information.