Mohammed T. Abou-Saleh

VASCULAR DEMENTIA 257causes low blood pressure, the question arises whether cerebralchanges may induce high blood pressure. Recently, it was shownthat infusion of Ab 42 (a protein deposited in the brains andcerebral vessels of AD victims) increased blood pressure inanaesthetized rats, suggesting that circulating levels of this proteinmay exert vasopressor actions in vivo 12 .Treatment of hypertension may thus have a preventive effect oncognitive decline and dementia. The recent finding from the Syst-Eur trial 13 , that treatment of isolated systolic hypertension reducesthe incidence of dementia by 50%, supports this hypothesis, butthe number of demented in that study was small. It has beensuggested that overtreatment with antihypertensive drugs mayincrease the risk of dementia in the very old by causing cerebralhypoperfusion. No studies so far provide support for this opinion.We recently reported 14 that subjects who became demented duringa 15-year follow-up used antihypertensive drugs less often thanthose who did not become demented. Although these findings donot preclude the possibility that overtreatment of hypertensionmay cause ischaemia in the brain in a subset of individuals, theydo not support the hypothesis that antihypertensive treatmentmay cause cognitive impairment in the elderly.REFERENCES1. Launer LJ, Masaki K, Petrovitch H et al. The association betweenmidlife blood pressure levels and late-life cognitive function. TheHonolulu–Asia Aging Study. J Am Med Assoc, 1995; 274: 1846–51.2. Elias MF, Wolf PA, D’Agostino RB et al. Untreated blood pressurelevel is inversely related to cognitive functioning: the FraminghamStudy. Am J Epidemiol, 1993; 138, 353–64.3. Skoog I, Lernfelt B, Landahl S et al. A 15-year longitudinal study onblood pressure and dementia. Lancet 1996a; 347, 1141–5.4. Sparks DL, Scheff SW, Liu H et al. Increased incidence ofneurofibrillary tangles (NFT) in non-demented individuals withhypertension. J Neurol Sci, 1995; 131: 162–9.5. Skoog I, Andresson L-A, Palmertz B et al. A population-based studyon blood pressure and brain atrophy in 85 year-olds. Hypertension1998a; 32: 404–9.6. Skoog I. A review on blood pressure and ischaemic white matterlesions. Dement Geriat Cogn Disord 1998b; 9(suppl 1): 13–19.7. Johansson BB. Pathogenesis of vascular dementia: the possible role ofhypertension. Dementia 1994; 5: 174–6.8. Skoog I, Wallin A, Fredman P et al. A population-study on blood–brain barrier function in 85 year-olds. Relation to Alzheimer’s diseaseand vascular dementia. Neurology 1998c; 50: 966–71.9. Skoog I. Arterial hypertension and Alzheimer’s disease. In Leys D,Pasquier F, Scheltens P, eds, Stroke and Alzheimer´s Disease. TheHague: Holland Academic Graphics 1998d; 89–100.10. Persson G, Skoog I. A prospective population study of psychosocialrisk factors for late-onset dementia. Int Geriat Psychiat 1996; 11:15–22.11. Burke WJ, Coronado PG, Schmitt CA et al. Blood pressureregulation in Alzheimer’s disease. J Autonom Nerv Syst, 1994; 48:65–71.12. Arendash GW, Su GC, Crawford FC et al. Intravascular b-amyloidinfusion increases blood pressure: implications for a vasoactive role ofb-amyloid in the pathogenesis of Alzheimer’s disease. Neurosci Lett,1999; 268: 17–20.13. Forette F, Seux ML, Staessen JA et al. Prevention of dementia inrandomised double-blind placebo-controlled Systolic Hypertension inEurope (Syst-Eur) trial. Lancet 1998; 352: 1347–51.14. Skoog I, Lernfelt B, Landahl S. High blood pressure and dementia.Lancet 1966b; 348: 65–6.