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Continuum of cognitive impairment to stroke possibly via atrial fibrillation.

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LETTER/REPLIES
Continuum of Cognitive Impairment to Stroke
Possibly via Atrial Fibrillation
Jacob I. Haft, MD
In their paper ‘‘Incident Cognitive Impairment Is Elevated in
the Stroke Belt: The REGARDS Study,’’1 the authors demonstrate that the incidence of development of cognitive
impairment is higher in a population in which the incidence
of stroke is higher, suggesting that the mechanism for stroke
and cognitive impairment is the same (at least in some
patients) and that there may be a continuum between cognitive impairment and stroke, that is, cognitive impairment is
an early and mild manifestation and stroke is an extreme
manifestation of the same underlying pathophysiologic abnormality. Previous studies, referenced in their paper, have
demonstrated a high incidence of the conventional risk factors for stroke in patients with cognitive impairment,
although not in the same population group. Were the individual patients who developed cognitive impairment followed
longitudinally, and was there an increased incidence of subsequent overt stroke in these patients?
We have documented that atrial fibrillation, largely
intermittent and undiagnosed, is found in a high incidence
in stroke patients (at least 34.9% among ischemic stroke
patients with hypertension2) in whom all electrocardiograms (ECGs) in a >14-year ECG and clinical database
were reviewed, suggesting that intermittent atrial fibrillation may be the common mechanism whereby the conventional risk factors for stroke cause stroke. Are data available on the incidence of atrial fibrillation in patients in
the Stroke Belt compared to the incidence of atrial fibrillation in patients in non-Stroke Belt states, and specifically,
are there data on the incidence of atrial fibrillation in the
patients in this study who developed cognitive impairment?
If there is a higher incidence of atrial fibrillation in these
patients, it might be advantageous to study patients with
increasing dementia with (1) magnetic resonance imaging
to identify those with multiple small silent infarcts and/or
(2) echocardiograms to find left atrial enlargement, left
ventricular enlargement, or low ejection fraction and to
identify patients most likely to benefit from long-term
monitoring to diagnose occult intermittent atrial fibrillation, who might then be considered for anticoagulation to
prevent overt stroke.
Potential Conflicts of Interest
Nothing to report.
Hackensack University Medical Center, Hackensack, NJ
C 2011 American Neurological Association
666 V
References
1.
Wadley VG, Unverzagt FW, McGuire LC, et al. Incident cognitive
impairment is elevated in the Stroke Belt: the REGARDS study.
Ann Neurol 2011;70:229–236.
2.
Haft JI, Teichholz LE. Echocardiographic and clinical risk factors
for atrial fibrillation in hypertensive patients with ischemic stroke.
Am J Cardiol 2008;102:1348–1351.
DOI: 10.1002/ana.22618
Reply
Virginia G. Wadley, PhD,1 Virginia J. Howard, PhD,1
George Howard, DrPH (REGARDS Study Principal
Investigator),1 and Elsayed Z. Soliman, MD2
We appreciate the opportunity to respond to Dr Jacob
Haft’s queries and good suggestions. We agree with Dr Haft’s
perspective regarding the probability of shared pathways for
incidence of cognitive impairment and stroke, including atrial
fibrillation (AF). Our recent Annals of Neurology publication
was part of a larger effort to better understand multiple traditional and novel risk factors for cognitive decline and stroke.1
To this end, an analysis of Framingham stroke risk factors and
incident cognitive impairment in the REGARDS cohort is currently in press.2
With respect to Dr Haft’s questions as to whether individuals who developed cognitive impairment were followed longitudinally, and whether there was an increased incidence of
subsequent overt stroke in these participants, the answer to
both questions is yes. We recently reported that low cognitive
performance is a potent predictor of physician-adjudicated incident stroke among REGARDS participants younger than 72
years (ie, ages 45–72 years).3
In the population-based REGARDS study, AF was determined at baseline from study scheduled electrocardiograms
(ECGs) recorded in participants’ homes, as well as by selfreported history of a previous physician diagnosis of AF. We have
shown in prior work that the prevalence of AF defined by ECG
plus self-report (ie, AF detected by both methods) is actually
lower in the Stroke Belt than the rest of the nation, although this
relationship was attenuated and no longer significant when defining AF by either self-report or ECG.4 Thus, our data do not support regional variations in AF that mirror regional differences in
incident cognitive impairment and stroke. Even so, we also have
demonstrated that irrespective of detection method, AF is a
strong and significant predictor of incident stroke (odd ratios
ranging from 1.41 to 1.90 depending on case definition).5 To
date we have not collected data for determining the geographic
distribution of incident or intermittent AF.
We appreciate Dr Haft’s suggestions for future research
directions as we continue our efforts to identify modifiable risk
factors for stroke and cognitive decline.
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stroki, atrial, possible, impairments, cognitive, continuum, fibrillation, via
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