Objective: Associations between the outcome of 24 h ambulatory monitoring and cognitive performance were studied in order to evaluate the potential relevance of ambulant blood pressure status to brain function. It was hypothesized that a small daytime–night-time difference in mean blood pressure (nondipping) is associated with reduced cognitive performance, in line with studies in hypertensive subjects that have reported associations between nondipping and target-organ damage.
Methods: The study followed a cross-sectional design and was part of a larger research programme on determinants of cognitive aging (Maastricht Aging Study, MAAS). A group of 115 community residents aged 28–82 years was recruited from a general practice population and screened for cardiovascular events and medication use. All underwent 24 h blood pressure monitoring. Cognitive performance was measured with tests of verbal memory, attention, simple speed and information processing speed.
Results: Mean daytime or night-time levels of both systolic and diastolic blood pressure were unrelated to cognitive outcome, when age, sex and educational level were controlled for. Differences between mean daytime and night-time blood pressure (based on both narrow and wide measurement intervals for day and night-time periods) were positively associated with memory function (5–9% of additional variance explained) and one sporadic positive association was found on the sensorimotor speed score (4%). Nondippers (n = 15) showed lower levels of both memory and sensorimotor speed scores.
Conclusions: Ambulatory blood pressure status was not associated with cognitive performance. A reduced nocturnal blood pressure drop was associated with quite specific cognitive deficits, but the underlying mechanism remains to be determined.
1Department of Psychiatry and Neuropsychology, Maastricht University, Maastricht
2Department of Internal Medicine, Eemland Hospital, Amersfoort
3Department of General Practice, Maastricht University, Maastricht
4Department of Internal Medicine, Maastricht University, Maastricht, The Netherlands.
5Correspondence to M.P.J. van Boxtel, MD, PhD, European Graduate School of Neuroscience (EURON), Maastricht University, Department of Psychiatry and Neuropsychology, P.O. Box 616, 6200 MD Maastricht, The Netherlands. Tel: +3143 3881028; fax: +3143 3671096; e-mail: email@example.com
Sponsorship: This work was supported in part by a grant from the Dutch Ministries of Education and Health & Welfare, via the Steering Committee for Gerontological Research (NESTOR). It is part of the Maastricht Aging Study (MAAS).
Received 9 February 1998 Revised 20 April 1998 Accepted 2 June 1998