Inveterate cell-phone addicts may feel that the devices help them to work smarter, and -- surprisingly -- they may be right.
If they're mice, that is.
In mice prone to an animal form of Alzheimer's disease, long-term exposure to electromagnetic radiation typical of cell phones slowed and reversed the course of the illness, according to Gary Arendash of the University of South Florida in Tampa and colleagues.
A similar exposure in normal mice -- for two hours a day over seven to nine months -- improved their cognitive abilities compared with controls, Arendash and colleagues said in the January issue of the Journal of Alzheimer's Disease, which is the research journal of the Alzheimer's Association.
The findings provide "striking evidence for both protective and disease-reversing effects" of long-term exposure to radiation at cell phone levels, Arendash and colleagues said.
But outside experts cautioned that the science in the study -- while mainstream -- is still very early.
"You just have to remember where you are in the mainstream -- right up at the head of it," said Bill Thies, chief medical and science officer of the Alzheimer's Association.
Thies told MedPage Today that the research needs to be repeated and confirmed, and various aspects of it need more study, before it's ready for prime time.
"This is no call for anyone to self-medicate," Thies said.
Other reactions to the study ranged from "interesting" to "nonsense."
Neurologist Dr. Alan Lerner of Case Western Reserve University and University Hospitals Case Medical Center in Cleveland, Ohio, said in an email the researchers took an "an innovative approach to modulating Alzheimer's disease models in mice."
But he said it's too early to say whether the finding have any relevance to humans.
Dr. Roger Brumback of Creighton University in Omaha, Neb. cautioned that even science published in reputable journals can turn out to be wrong, adding "extreme caution is necessary until this outcome has been confirmed independently in other laboratories."
Moreover, he said in an email, even if the science is correct, "humans are not just big mice, and we must always be cautious in extrapolating results from mice to man."
Zaven Khachaturian, editor of Alzheimer's & Dementia, responded even more bluntly: "This is nonsense."
In an email, Khachaturian said, "It is a mice study and there are number of other secondary factors [other than radio signals from cell phones] that could account for the results."
Arendash and colleagues said in the journal they had expected to find cognitive function worsened in the mice exposed to radiation, likely as a result of oxidative stress in the brain.
Instead, "it surprised us to find that cell phone exposure, begun in early adulthood, protects the memory of mice otherwise destined to develop Alzheimer's symptoms," Arendash said in a statement.
"It was even more astonishing that the electromagnetic waves generated by cell phones actually reversed memory impairment in old Alzheimer's mice," he said.
The report comes almost exactly two years after researchers at the University of Sunderland, in England, said they had shown that infrared light could improve cognition in mice.
That report led to the development of the so-called "Alzheimer's helmet," aimed at slowing or reversing the disease in humans. Whether that works has not been shown yet.
For this study, the researchers studied transgenic mice that progressively lose cognitive function at the same time as they develop amyloid plaques in their brains, similar to those seen in human Alzheimer's patients.
On the other hand, the animals don't develop other hallmarks of the human disease, such as loss of neurons and the development of neurofibrillary tangles, the researchers noted.
Mice -- both transgenic and normal type littermates -- were exposed to electromagnetic waves at cell phone levels of 918 megaHertz with a specific energy absorption rate of 0.25 Watts per kilogram. The exposure lasted for an hour twice a day.
Transgenic and normal type mice that weren't exposed to the radiation acted as controls. Cognitive function was measured using a so-called radial arm water maze, a standard method of testing memory in mice.
The researchers used the maze to generate a test that they said was functionally equivalent to tests used in humans that can distinguish between Alzheimer's, mild cognitive impairment, and normal cognition.
They conducted two main experiments, one in adolescent mice and one in older animals.
In the first, radiation exposure began at two months, before the transgenic animals had begun to lose cognitive function, and maze tests 2.5 months showed no difference in function between the groups of animals.
Subsequent tests -- at four months and seven months -- showed the un-exposed transgenic mice losing cognitive function, while the normal animals and the exposed transgenic mice did not.
Interestingly, in this experiment, the exposed normal mice also did significantly better than all other groups on a so-called "Y-maze alternation test," which measures basic memory function, the researchers reported.
In the second experiment, the researchers waited to start radiation exposure until the age of five months, when the transgenic animals had started to show signs of cognitive decline.
Testing two and five months later showed no evidence of benefit or harm, the researchers said, but after eight months of exposure to radiation, the transgenic mice had recovered some cognitive function and were significantly better than transgenic controls.
In the transgenic animals, radiation exposure was also associated with changes in the deposition of amyloid in the brain, including an increase in the more soluble form of the protein, the researchers said.