Washington, Nov 4 (IANS): Health apps are a new fad among US citizens, especially youngsters, but many of them are not using them at all, finds an online national survey, adding that over time, many such apps are left unused by those who download them.

The researchers from New York University's Langone Medical Centre found that 58 percent of 1,604 adult smartphone users had downloaded one of the estimated 40,000 available health-related mobile applications and 42 percent had downloaded five or more.

Some 65 percent of those surveyed said the apps had improved their health, and a majority also had a strong degree of faith in health apps' accuracy and effectiveness.

But there were downsides as well. Forty-six percent reported having downloaded an app they no longer used.

In addition, concerns about cost, disinterest over time and privacy were apparent barriers to wider and more effective use of the apps.

In the survey population, those most likely to use health apps were overall younger, more educated, of higher income or obese (with a body mass index of 30 or more).

“Our study suggests that while many Americans have embraced health apps along with their smartphones, there are challenges to keeping users engaged, and many Americans who might benefit are not using them at all," explained Paul Krebs, lead investigator and clinical psychologist.

“There is still much more to be learned about how we can make best use of the wide variety of health apps now available -- not just for fitness and nutrition but for other purposes such as monitoring sleep and scheduling medical appointments,” he pointed out.

The most downloaded and used health apps are related to personal fitness and nutrition: to track physical activity (53 percent), food consumption (48 percent), weight loss (47 percent), and exercise instruction (34 percent).

Some 65 percent of respondents, equally split among men and women, reported using their apps daily.

According to Krebs, the most common reasons for people not downloading apps were lack of interest, cost, high volume of information that needed to be entered on a daily basis, and concern about apps collecting their personal data.

“Smartphone apps have tremendous potential to help market healthy lifestyle habits to people who may be harder to reach in other ways, especially minorities, and those with lower incomes and serious health problems,” added study senior investigator Dustin Duncan.

Duncan, however, pointed out that more research is needed into applying health apps' and their special ability to reach medically underserviced groups to maximise the impact of their app use on their overall health.

The study appeared in the Journal of Medical Internet Research mHealth and uHealth.