Researchers followed 7,087 French people over 65 for four years to see what factors were most clearly linked to losses in mental performance that fell short of dementia. Many seniors--including 15.8% of the sample--are diagnosed with metabolic syndrome, defined by these researchers as having two of the following five biomarkers: high blood pressure, a large waist circumference, a high overall cholesterol reading, a particularly low score on HDL (or "good") cholesterol, and high levels of circulating blood sugar. Metabolic syndrome puts them at higher risk of developing cardiovascular disease. But the current study, published in the journal Neurology on Wednesday, provides strong evidence that brain function, too, is affected.
The French researchers gauged mental decline by three different measures, and acknowledged that none was a perfect instrument for detecting cognitive impairment. But different elements of the metabolic syndrome were tied to performance deficits on each measure.
People with high overall cholesterol levels or low HDL were most likely to show signs of mental decline on the Mini-Mental Status Examination, a crude overall measure of mental functioning. People with high blood pressure and those whose high blood sugar warranted a diabetes diagnosis were most likely to show cognitive impairment on a test that measured visual working memory. And those with low HDL cholesterol or diabetes tended to perform poorly on the test that gauged verbal fluency.
Collectively, those findings suggest that factors that worsen heart attack and stroke risk may exercise negative effects on the brain well short of a full-on stroke.
The researchers wrote that, theoretically, people who aggressively manage their metabolic syndrome risks (who take medication, for instance, for blood pressure or high cholesterol) should also cut their added risk of cognitive decline and postpone the onset of dementia. But that still needs to be established by a large trial that followed older subjects for a longer period.