The H1N1 swine flu that has been making headlines is but one species in an infamous H1N1 lineage that has circulated among human populations since 1917 - and the H1N1 lineage is one branch of numerous flu virus species. While flu viruses present themselves through the physical respiratory symptoms we have long associated with them, it is now apparent that their impact is more dangerous and profound than we had understood prior.
I spoke with Dr. Hossein Fatemi
, Professor of Psychiatry, Pharmacology and Neuroscience at the University of Minnesota Medical School. Dr. Fatemi has been studying the link between H1N1 specifically and autism and schizophrenia since 1998. His work has centered on mice, but the lessons learned certainly translate to human populations and to other mammals.
Some diseases have been directly linked to viral infections. For example, Human Papillomavirus - or HPV as it is more widely known - begins as a viral infection of the skin and mucous membranes. It is the most common sexually transmitted disease, and most people do not develop any symptoms and are unaware that they are infected. Some strains of HPV cause cervical cancer and other cancers of the vagina, penis, anus, and vulva.
So the transition from a more "simple" viral infection to a more profound disease - like cancer - has been uncovered, and in the case of HPV a vaccine has been developed. But what if a common seasonal flu virus could be wreaking unknown and long-term havoc on the invisible switches of our biology?
In the 1990s, evidence emerged that pregnant mothers who had been infected by the flu had given birth to children with schizophrenia. Scientists followed a hunch, needing to know if the flu virus was impacting the brain development of unborn babies.
"We asked a simple question," Dr. Fatemi said. "If we infect pregnant mice at various gestations with H1N1, does it cause abnormalities in the offspring's brain development. The experiment looked at the impact of H1N1 infection on brain genes in the hippocampus and in the cerebellum."
The findings were staggering
and pointed to a direct connection between flu infection and the onset of autism, schizophrenia, and other gray and white matter afflictions.
"A large number of brain genes were affected significantly in both the hippocampus and cerebellum," said Dr. Fatemi.
The virus was scrambling key genes associated with brain development triggers.
Schizophrenia's causes remain vague. Could a common flu virus be responsible?
"Experts now agree that schizophrenia develops as a result of interplay between biological predisposition (for example, inheriting certain genes) and the kind of environment a person is exposed to," according to Schizophrenia.com
. "These lines of research are converging: brain development disruption is now known to be the result of genetic predisposition and environmental stressors early in development (during pregnancy or early childhood), leading to subtle alterations in the brain that make a person susceptible to developing schizophrenia."
Could the environmental factors that contribute to schizophrenia be found in a mother's seasonal flu infection?
The mystery of autism has been a cause of great debate around the world. Autism has been on the rise - and this has been an unexplained phenomenon. A number of studies have looked at mercury levels in vaccination dosages, but most experts rely on the usual explanation that autism is a result of a combination of genetic and environmental factors. In other words, there is no answer for why autism occurs.
"Some cases of autism may be a consequence of these natural infections," Dr. Fatemi said.
Dr. Fatemi's look at flu infection may offer a broader understanding of how psychological disorders may be emerging from viral sources. His work extends beyond autism and schizophrenia, and his findings may uncover the broad impact that common flu infections can have on pregnant women and their unborn babies.