EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, DECEMBER 8, 2003
To contact Johanna M. Seddon, M.D., Sc.M., call Mary Leach 617/573-4170.

DIETARY FATS MAY INCREASE THE RISK OF AGE-RELATED MACULAR DEGENERATION

CHICAGO—High intake of dietary fats may increase the risk of progression of age-related macular degeneration, according to an article in the December issue of The Archives of Ophthalmology, one of the JAMA/Archives journals.

According to information in the article, age-related macular degeneration (AMD, a common, progressive eye disease in older people that causes blindness) is the leading cause of irreversible visual impairment and blindness in the United States and in other developed countries. Six percent to eight percent of people aged 75 and older have the advanced stages of AMD associated with blindness. It is estimated that more than eight million people have the intermediate stages of AMD, and of these about 1.3 million people will develop advanced AMD within the next five years.

Johanna M. Seddon, M.D., Sc.M., of the Massachusetts Eye and Ear Infirmary, Boston, and colleagues evaluated the associated between dietary fat intake, including specific types of fat, on rates of progression of AMD in a large population at risk for vision loss.

The researchers studied 261 patients aged 60 or older who had some sign of AMD in at least one eye. Participants were followed for an average of 4.6 years and completed food frequency questionnaires designed to measure the amounts and kinds of foods eaten in the previous week.

The researchers found that consumption of dietary fats and fat-containing food groups modified the risk of progression to advanced AMD, whereas fish and nut consumption reduced the risk.

EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, DECEMBER 8, 2003
To contact Elisabeth Kvaavik, M.Sc., e-mail ekvaavik{at}basalmed.uio.no.

FOUNDATION FOR ADULT BODY WEIGHT MAY BE LAID DURING ADOLESCENCE

CHICAGO—Adolescent body mass index and changes in physical activity between adolescence and adulthood are good predictors of BMI in adulthood, according to an article in the December issue of The Archives of Pediatrics & Adolescent Medicine, one of the JAMA/Archives journals.

According to the article, in recent decades, body mass index (BMI, weight in kilograms divided by the square of height in meters) and the proportion of overweight and obese people has increased worldwide. Several studies have shown that tracking (patients maintaining their relative positions weight-wise in their age-sex group over time) is fairly common.

Elisabeth Kvaavik, M.Sc. of the Institute for Nutrition Research, Oslo, Norway, and colleagues examined tracking of BMI from age 15 to 33 to assess the effects of adolescent and adult health behavior and parent’s BMI and education on adult BMI. They also examined changes in lifestyle factors (such as smoking and amount of physical activity) as predictors of adult overweight and obesity.

The researchers followed-up 485 adolescents (average age a the beginning of the study, 15 years) from Oslo, Norway, for 18 to 20 years. The study began in 1979. Weight, height, physical fitness, leisure time physical activity (LTPA), smoking and education were assessed at the beginning of the study and at follow-up. Parents height, weight and education were assessed at the beginning of the study.

EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, DECEMBER 8, 2003
To contact Ida Martinelli, M.D., Ph.D., e-mail martin{at}policlinico.mi.it. To contact Thomas Schwarz, M.D., e-mail tho_schwarz{at}hotmail.com.

AIR TRAVEL MAY INCREASE THE RISK OF BLOOD CLOTS, ESPECIALLY LONG FLIGHTS

CHICAGO—Two articles in the December 8/22 issue of The Archives of Internal Medicine, one of the JAMA/Archives journals, report an increased risk of blood clots associated with air travel.

Venous thromboembolism (VTE, or formation of blood clots in the veins) result from an interaction between genetic and environmental factors, according to information in the article. Genetic factors can include a lack of certain proteins in the blood that help prevent or break up clots, and environmental factors include the use of oral contraceptives, recent surgery, cancer, pregnancy and prolonged immobilization. Studies have suggested that air travel may be a risk factor in VTE.

Ida Martinelli, M.D., Ph.D., of the University of Milano, Italy, and colleagues investigated whether individuals with certain genetic predispositions for developing VTE and those taking oral contraceptives are more likely to develop VTE during flights than those without these risk factors.

Thomas Schwarz, M.D., of the University of Dresden Medical School, Germany studied the incidence of VTE associated with "long-haul" flights lasting eight hours or longer.

Dr. Martinelli and colleagues studied 210 individuals with VTE and 210 controls without VTE. DNA analysis and blood tests were performed on all participants to look for genetic factors and levels of blood components associated with an increased risk of VTE.

In the month preceding VTE (or for controls, during the previous month), air travel was reported by 31 patients (15 percent) and 16 controls (8 percent). The researchers found that 102 (49 percent) of patients who had VTE had factors that increased their risk for VTE compared with 26 (12 percent) of controls. Oral contraceptives were used by 48 patients with VTE, and by 19 controls.

The researchers found that the risk of VTE in patients with genetic or other risk factors for VTE and who had traveled by air in the past month was 16 times higher compared to patients without these risk factors. Women who used oral contraceptives and traveled by air in the past month were 13 times as likely to develop VTE.

"Air travel is a mild risk factor for venous thromboembolism, doubling the risk of the disease," write the researchers.

Dr. Schwarz and colleagues studied 964 passengers returning from long-haul flights (longer than eight hours) and 1,213 control participants who did not fly. Venous thrombosis was documented in 27 passengers (2.8 percent) and 12 controls (1.0 percent); of these, 20 passengers (2.1 percent) and 10 controls (0.8 percent) had isolated calf muscle venous thrombosis.

EMBARGOED FOR RELEASE UNTIL 3 P.M. (CT), MONDAY, DECEMBER 8, 2003
To contact Theodore Jacob, Ph.D., e-mail tjacob{at}pgsp.edu.

GENETICS AND FAMILY ENVIRONMENT INFLUENCE LIKELIHOOD OF DEVELOPING ALCOHOLIC DISORDERS

CHICAGO—Family environmental influences can be important factors in the development of alcohol abuse disorders in offspring with increased genetic risk for alcoholism, according to an article in the December issue of The Archives of General Psychiatry, one of the JAMA/Archives journals.

According to the article, although considerable evidence suggests that genetics plays a role in the development of alcohol dependence (AD), the offspring-of-twins design has been used infrequently to assess these effects. This design allows researchers to look at both genetic and environmental risk factors based on the twin's history of alcoholism. For example, children raised by an alcoholic monozygotic (MZ, or identical twin) or dizygotic (DZ, non-identical twin) twin parent are at high risk for psychiatric disorders including alcoholism because they are at both high genetic and environmental risk (studies have shown that children raised by alcoholics are more likely to become alcoholics themselves). In contrast, children raised by the non-alcoholic MZ twin of an alcoholic are at a low environmental risk because the children did not grow up in an alcoholic household. However, these children have the same high genetic risk as the children raised by the alcoholic twin because the fathers have the same genes. Children raised by the non-alcoholic DZ twin of an alcoholic are also at a lower environmental risk for alcohol dependence, but are at an intermediate genetic risk because DZ twins share only half their genes.

Theodore Jacob, Ph.D., of Palo Alto Veterans Affairs Health Care System, Menlo Park, Ariz., and colleagues used the offspring-of-twins design to study the effects of genetics and environment on the risk of developing alcohol dependence.

The researchers conducted telephone interviews with 1,213 male MZ and DZ twins who had been enrolled in the Vietnam Era Twin Registry. The registry is composed of male-male twin pairs born between January 1, 1939 and December 31, 1957, who served in the U.S. military between May 1, 1965 and August 31, 1975. This study included registry members who had completed an interview in 1992 and reported having children born between 1974 and 1988. The researchers also interviewed 1,270 children of the twins and 862 mothers of these children. The interviews consisted of detailed information about psychiatric disorders, including alcohol abuse and alcohol dependence. The fathers and mothers averaged 50 and 47 years old.

This study focuses on the diagnosis of alcohol abuse or alcohol dependence among the offspring of the twins.

The offspring ranged in age from 12 to 26 years old, whereas the average age of the twins fathers was 50 years old and the average age of the mothers was 47 years old. Among offspring, 276 had MZ or DZ twin fathers who had no alcohol abuse or alcohol dependence. In the rest of the offspring, either their twin father or their twin father’s brother, or both had alcohol abuse or alcohol dependence.

The researchers found that children of MZ and DZ twins with a history of alcohol dependence were significantly more likely to exhibit alcohol abuse or alcohol dependence than were children of non-alcoholic fathers. Children of an alcohol-abusing MZ twin whose co-twin was alcohol dependent were more likely to be alcohol dependent than children of non-alcoholic twins. Children of a MZ twin with no history of alcohol abuse or dependence whose co-twin was alcohol dependent were no more likely to be alcohol abusers or alcohol dependent that the children of non-alcoholic twins.