Hypertension causes cognitive impairment, involving mainly executive functions, but the effect of blood pressure (BP) control on the different cognitive domains is still debated. We correlated executive function, attention and memory with BP control and cerebrovascular damage in 60 undemented middle-aged hypertensives at baseline and after 6-year follow-up. At first evaluation, the patients with poor BP control had higher score of white matter lesions, reduced cerebrovascular reserve capacity and greater carotid intima-media thickness (IMT) than those with good BP control. Performance on executive tests correlated with IMT and with performance on attention tests, which was impaired by low diastolic BP. At long-term follow-up, performance in attention and executive tests improved in spite of the minor improvement of BP control, increased IMT and worse memory. Low diastolic BP has a negative effect on attention, which affects executive performance at first cross-sectional examination. This confounding effect has to be taken into consideration when planning studies on cognitive function. Longitudinal studies are required to unravel the effect of BP control on cognitive function, as only long-term antihypertensive treatment improves both attention and executive performance.