The new study backs up the theory that modern children are too ‘clean’ for their own good as the immune system can over-react if it doesn’t have enough viruses to fight

Catching viruses such as flu when you’re younger could protect your from developing allergies later in life, a new study has found.

It adds to evidence that a growing number of children in developed countries are suffering from allergies because they are not exposed enough to bacteria and viruses.

In the latest research, scientists from Harvard Medical School found baby mice infected with the influenza A virus grew into adults that were protected against induced symptoms of the condition.

However, adult animals catching flu remained susceptible to asthma.

Scientists traced the effect to a sub-group of immune system cells called natural killer T-cells (NKT cells).

Some NKT cells appear to keep the immune system under control and prevent the extreme reactions that lead to allergies such as asthma. In the baby mice with flu, but not the adults, numbers of these cells were found to increase.

The research also showed that NKT cell protection against asthma could be induced by exposing baby suckling mice to a molecule from the stomach bug Helicobacter pylori.

The findings, published in the Journal of Clinical Investigation, provide strong evidence in support of the ‘hygiene hypothesis’ – the theory that we are too clean for our own good.

Early infections may ‘prime’ the immune system to prevent it over-reacting to allergy triggers later in life, according to the theory.

The scientists, led by Dr Dale Umetsu, wrote: ‘Our results suggest that infection with certain micro-organisms can prevent the subsequent development of asthma and allergy by expanding the relative proportion of a specific subset of NKT cells, thus providing an immunological mechanism for the hygiene hypothesis.’

Treating children with drugs that activate protective NKT cells may block the development of asthma, the researchers concluded.

HACKENSACK, N.J. — a New Jersey neuroscientist deeply involved in Alzheimer’s research said that in just two years, doctors may have the medicine to treat the brain-killing disease.

Dr. Howard Fillit, also a geriatrician and executive director of the Alzheimer’s Drug Discovery Foundation, said this week that more than 150 clinical trials worldwide are testing dozens of drugs that may be the answer to combating the disease itself, and not just the symptoms.

“Currently the drugs we have are purely for treating the symptoms, but we’re hoping the new ones will slow down the progression of the disease — and ultimately, prevention is the goal,” said Fillit, of Tenafly. “Some of the drugs are in the final phases of testing and we’ll have the reports in two years on whether they work.”

Alzheimer’s is the most common form of dementia, caused by the destruction of nerve cells in the brain. it is usually fatal, initially causing memory failure, personality changes and problems completing daily activities until its progression leaves a patient unable to walk, speak, or swallow.

Five million Americans suffer with Alzheimer’s. More than 80 of the ongoing clinical trials are occurring in the State of New Jersey, said Ed Belkin, vice president of communications and public affairs with Pharmaceutical Research and Manufacturers of America, a trade association for biotech research companies.

“As the baby boomers age, the number of Alzheimer’s patients will swell and the financial costs are just not sustainable,” Belkin said. “Medical advancements are the answer, and research scientists are committed to win this battle against Alzheimer’s.”

In 2009, the average annual compensated cost for a patient with Alzheimer’s was $33,000 and the estimated cost for unpaid caregivers was $4.2 billion, Belkin said.

Researchers believe Alzheimer’s is caused by two abnormal conditions in and around neurons — the nerve cells in the brain. Plaques, which are deposits of a protein fragment called beta-amyloid, build up in the spaces between neurons and are believed to block communication between them. In healthy brains, scientists believe these proteins are broken down and eliminated.

Fillit said scientists aren’t yet sure if the plaque causes the disruption or is just a scar left by the brain as it degenerates.

“If the drugs can remove the plaque, it should slow the rate of the disease,” Fillit said. “But we’re not sure if the plaque is the cause or a scar.”

The other abnormal finding is tangles. these are twisted fibers of a protein called tau located within the neuron. normally, tau form structures to transport nutrients and other substances from one part of the cell to another. In Alzheimer’s patients, however, these structures are abnormal and collapse, leading to the death of the cells. The new drugs should prevent the structures from collapsing.

“These tangles are the tombstones of the cells,” Fillit said. “But with these new drugs, I am very hopeful we will soon conquer this nightmare of old age.”