Neurology -- Correspondence for Verghese et al., 61 (12) 1667-1672

Correspondence published:

Reply to Zuccala et al: Joe Verghese (3 February 2004)

Low blood pressure and the risk of dementia in very old individuals: Giuseppe Zuccala, Roberto Bernabei (3 February 2004)

Reply to Zuccala et al 3 February 2004

Joe Verghese,
Albert Einstein College of Medicine
1165 Morris Park Avenue, Bronx, NY 10461
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Re: Reply to Zuccala et al

jverghes{at}aecom.yu.edu Joe Verghese

We thank Dr. Zuccala et al for their interest in our study. Our preliminary analysis did show a trend towards increased risk of dementia with low diastolic (but not systolic) blood pressure in women. However, the relatively small number of men (n = 145) in our sample did not allow us to make meaningful comparisons.
The category of ‘cardiac disease’ included a history of cardiac failure, previous myocardial infarction and coronary artery disease, as previously defined. [6] These variables did not individually influence the association between low blood pressure and incident dementia, and hence, were combined in our analysis. The lack of a significant association probably reflects differences in study designs and the severity of medical illnesses, especially cardiac failure, in our prospective community-based volunteer cohort and the previously reported cross-sectional hospital-based study. [3]
We agree that medical conditions such as cardiac failure, which may predispose to cerebral hypoperfusion, and gender differences need to be further explored in other older populations to identify at-risk individuals.
References
6. Verghese J, Lipton RB, Katz MJ, et al. Leisure activities and the risk of dementia in the elderly. N Engl J Med 2003; 348: 2508-2516.

Low blood pressure and the risk of dementia in very old individuals 3 February 2004

Giuseppe Zuccala,
Catholic University
Chair of Gerontology, Catholic University, L.go F. Vito, 1 - 00168 Rome,
Roberto Bernabei
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Re: Low blood pressure and the risk of dementia in very old individuals

giuseppe_zuccala{at}rm.unicatt.it Giuseppe Zuccala, et al.

We read with interest the article by Verghese et al [1] which analyzed the association between arterial hypotension and incident dementia in an elderly cohort. The results of their study are important, particularly in the light of the relevant length of the follow- up. While the potential hazard of hypertension are well known in clinical practice, the possible role of hypotension as an occult cause of cognitive impairment in older populations is unclear.
Some points in their article need clarification. In Table 1, Verghese et al indicate that prevalent history of myocardial infarction at baseline did not differ among participants according to incident dementia. However, in the same population, an association between previous myocardial infarction and incident dementia has been reported among women, but not men. [2]
As lower blood pressure levels might reflect left ventricular dysfunction, the association between blood pressure and incident dementia should be assessed in men and women using separate models, rather than after simply adjusting for gender.
In addition, the authors did not consider the diagnosis of heart failure among medical variables, even though they cited a generic condition of “cardiac disease”. This point is relevant, as we found in a population of 13,635 older subjects that systolic blood pressure levels below 130 mm Hg were associated with increased probability of cognitive impairment among participants with diagnosis of congestive heart failure, but not among other subjects. [3]
Defining the role of hypotension in the genesis of cognitive impairment in older subjects with heart failure is not satisfactory, but it responds to an objective clinical need. Given the impressive prevalence of heart failure and unrecognized left ventricular dysfunction among the elderly, systolic hypotension might represent an occult cause of cognitive impairment, with ensuing disability and reduced survival in older populations. [4,5]
In our opinion, the existence of subpopulations with various underlying medical conditions – which have to be addressed using a multidisciplinary approach - should be acknowledged when investigating the association between arterial hypotension and dementia in older populations.
References
1. Verghese J, Lipton RB, Hall CB, Kuslansky G, Katz MJ. Low blood pressure and the risk of dementia in very old individuals. Neurology 2003;61:1667-1672.
2. Aronson MK, Ooi WL, Morgenstern H, et al. Women, myocardial infarction, and dementia in the very old. Neurology 1990;40:1102-1106.
3. Zuccalà G, Onder G, Pedone C, et al. Hypotension and cognitive impairment: Selective association in patients with heart failure. Neurology. 2001;57:1986-1992.
4. Zuccalà G, Onder G, Pedone C, et al. Cognitive dysfunction as a major determinant of disability in patients with heart failure: results from a multicentre survey. J Neurol Neurosurg Psychiatry. 2001;70:109-112.
5. Zuccalà G, Pedone C, Cesari M, et al. The effects of cognitive impairment on mortality among hospitalized patients with heart failure. Am J Med. 2003;115:97-103.