Older women who complain of memory problems are more likely to be diagnosed with thinking impairment or dementia decades later, according to a recent study.

Researchers found that women who had memory complaints were 70 percent more likely to develop a diagnosis of memory or thinking impairment during the study than women who did not have any memory complaints, Reuters Health reported.

"We do not know why some older adults develop concerns about their memory even though they are not showing memory problems on tests of thinking skills," study author Allison R. Kaup of the San Francisco VA Medical Center and the University of California San Francisco told Reuters Health. "One possibility is that an individual may be noticing changes in their memory that are so subtle that clinical tests do not detect it."

For the study, researchers collected and analyzed data from more than 1,100 dementia-free women with an average age of 70 years old, The Huffington Post reported. This group of women was asked several times over 18 years the same question: "Do you feel you have more problems with memory than most?" At the end of the study, women completed tests of thinking abilities to diagnose whether they had memory or thinking impairment. Other important factors such as years of education, depression, high blood pressure, diabetes, stroke and heart disease were considered.

At the start of the study, a total of 89 women, or 8 percent, complained of memory problems at the start of the study. They were 70 percent more likely to develop a diagnosis of memory or thinking impairment during the study than women who did not have any memory complaints, with 53 percent of those with complaints developing a diagnosis compared to 38 percent of those with no memory complaints.

Women who had memory complaints 10 years before the end of the study were 90 percent more likely to develop a diagnosis than those with no memory complaints at 10 years prior. Women who had memory complaints four years before the end of the study were three times more likely to develop a diagnosis than women with no memory complaints four years prior.

"Our findings, though modest, provide further evidence that memory complaints in aging deserve close attention as a possible early warning sign of future thinking and memory problems, even several years in advance," Kaup said.

The findings are detailed in the journal Neurology.