Investor optimism continues to fall among increased pessimism about the fate of the U.S. economy, according to the latest poll from Wells Fargo/Gallup Investors.

The group’s Investor and Retirement Optimism Index dropped to 24, down from 40 in February. Retirees were the most glum, with their optimism dropping to 17, from 38 in February. Non-retired investors’ optimism levels rated 27, also down from 41 in February.

Low interest rates are a leading source of worry. One in three investors say low interest rates will take a bite out of their portfolios and cause them to delay retirement. Some 45% of working investors and 34% of retirees worry that low rates will cause them to outlive their money while in retirement.

What’s more, 26% of working investors say the low rates mean they will likely put money into investors they might otherwise have avoided; 19% of retirees say the same. Thirty-two percent of all investors say they expect low rates to lead to a sharp uptick in inflation in the coming years.

This newly gloomy outlook is especially noteworthy in retirees, who were three times cheerier than working investors just a year ago. The low rates are challenging retirement nest eggs, and present a notable obstacle when core inflation rate growth is about 3% a year and CD rates are yielding less than 1%, according to Karen Wimbish, director of Retail Retirement at Wells Fargo. “Some people may feel like they’re pushing mud up a hill,” she said.

The non-retirees are slightly more sanguine about low rates, with 73% saying that the benefits to consumers and businesses outweigh the costs. Just 46% of retirees say the same.

Health care costs continue atop the list of worries for US investors, with three out of four investors dissatisfied with the overall cost of healthcare. Some 80% say the system is in a “state of crisis” or has “major problems.” Yet nine out of ten say the quality of their care is excellent or good, while eight out of ten say their insurance coverage is excellent or good.

Yet that coverage doesn’t come without cost. Two-thirds of investors report their insurance bills have climbed in the past year. Nearly one-third, or 29%, of retirees say rising health costs have cut into their ability to save for retirement, or even forced delaying retirement. 

Rising costs, lower interest rates and a choppy market have made investors more nervous, with just 48% saying in February that now is a good time to invest in the markets, compared with 52% a year ago. More than half, 57%, report feeling little or no control over their ability to build a retirement nest egg. Those with a written financial plan feel better, but just 28% of the working investors and 42% of retirees have such a plan.