NEW YORK (Reuters Health) - People who had polio in childhood seem to be at somewhat increased risk of being hospitalized for a psychiatric disorder later in life, according to a Danish study.

"Chronic and life-threatening diseases are known to be accompanied by increased risk of anxiety, depression, and suicide," Dr. Nete Munk Nielsen, of Statens Serum Institut, Copenhagen, and colleagues write in the American Journal of Epidemiology. "It has furthermore been suggested that certain medical conditions such as childhood infections of the central nervous system could subsequently increase the risk of psychosis and schizophrenia."

In their study, the researchers studied database information on 4660 people who had polio between 1922 and 1954, along with 19,017 age- and gender-matched "controls" who did not have polio. These subjects were then linked to national records for people who were hospitalized for a psychiatric disorder between 1977 and 1993.

"Overall, history of poliomyelitis was associated with a 40% increased risk of being hospitalized for a psychiatric disorder," Nielsen's group reports.

The likelihood of suffering a mental disorder seemed to be higher before age 45 years, and among those who had polio before the age of 7.

"The overall increased risk of psychiatric hospitalizations could not be confined to specific groups of psychiatric disorders," the investigators added. Rather, there seemed to be "slightly increased risks of several different disorders, especially milder psychiatric disorders." These included personality disorders, substance/alcohol abuse, and other non-psychotic mental disorders.

The team says the reason for the higher odds of having mental problems isn't really known, but they point out that it might relate to the "very painful and fearful" experience of contracting polio, the stringent isolation from family for several weeks, and the difficulties of then overcoming physical handicaps and social prejudice.

Whatever the cause, Nielsen and colleagues say their study "emphasizes the importance of supportive vigilance toward this group of people."