Low blood pressure in Down's syndrome - A link with Alzheimer's disease?

Low blood pressure is reported in Down's syndrome (DS). To assess this and determine whether low pressure results from the disease or from long-term residence in hospital, we measured blood pressure with a random-zero sphygmomanometer in three groups of patients: 52 DS inpatients, 62 DS outpatients, and 60 outpatients with other forms of mental handicap. Relative to normal reference populations, blood pressure was low in both DS inpatients (systolic, score -33 mmHg, P<.0001) and DS outpatients (-25 mm Hg, P<.0001). It was normal in non-DS outpatients (-4.0 mm Hg, P=.3). Blood pressure rose normally with age in the non-DS group but not in the DS group. We conclude that blood-pressure is low in DS and that this is a feature of the disease rather than of the protected environment in which patients live. A mechanism related to trisomy 21 is likely, and there may be a link with Alzheimer's disease (AD) because blood pressure is also low in Alzheimer's and a high proportion of DS patients develop this disease. If, as is likely, blood pressure is lowered in Alzheimer's by the neuropathy, the same neuropathy developing early in DS may also reduce blood pressure.