News today that low levels of the "good" HDL cholesterol raises a person's risk of memory loss and memory loss and dementia may send many folks rushing to their doctor for a cholesterol check. Indeed, the findings are pretty scary. Study participants with the lowest HDL levels—defined as less than 40 mg/dL—were 53 percent more likely to perform poorly on short-term memory tests compared to those with high HDL, defined as 60 mg/dL or greater. (These healthy participants were age 61, on average, experiencing the earliest signs of dementia that typically start in middle age.) Those whose HDL levels plunged over the six-year study also experienced a decrease in the number of words they were able to recall on the memory test, says study leader Archana Singh-Manoux, senior research fellow in epidemiology at the University College London.