Clinical Briefs: Alcohol Consumption and Risk of Dementia; Benefit of Atrial Pacing in Sleep Apnea Syndrome; Metabolic Syndrome Among US Adults
Alcohol Consumption and Risk of Dementia
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Observational studies indicate salutary effects of moderate alcohol consumption (MAC) upon incidence of stroke and myocardial infarction. Since some portion of dementia is attributable to cerebral vascular ischemic changes, the idea that MAC might favorably affect cognitive impairment or dementia appears plausible. To study this relationship, Ruitenberg et al performed a prospective observational analysis examining participants in the Rotterdam study, a group of almost 8000 adults in The Netherlands, age 55 or older. At baseline (enrollment 1990-1993), all subjects were ostensibly free of dementia. The study was completed in 1999.
Over a mean follow-up of 6 years, 197 persons developed dementia, of which Alzheimer’s disease was most frequent (74%), but vascular dementia was the next most common (15%).
Alcohol consumption was associated with a reduced risk of dementia. Persons who engaged in MAC had an 18-42% reduced likelihood of dementia when compared with heavy drinkers. Additionally, MAC persons had lower risk than non-drinkers. Both dementia (all forms combined) and vascular dementia alone showed comparable risk reduction patterns. No form of alcohol (beer, wine, liquor) showed a preferential effect. The fact that vascular dementia was reduced to a greater degree than Alzheimer’s is consonant with recognized impact of MAC upon such cardiovascular risk factors as platelet aggregation and lipids.
Ruitenberg A, et al. Lancet. 2002;359: 281-286.
Benefit of Atrial Pacing in Sleep Apnea Syndrome
Sleep apnea syndrome (SAS) has a diversity of immediate and distant consequences, including disrupted sleep, daytime fatigue resulting in traffic accidents, hypertension, increased cardiovascular morbidity, and increased mortality. Numerous therapies, none of which is wholly satisfactory for all patients, are available, including CPAP, theophylline, and surgical intervention. The serendipitous observation that persons who had received an atrial overdrive pacemaker noted improvement in SAS, combined with the knowledge that SAS is associated with both bradycardia and paroxysmal tacyharrhythmias, which might be favorably altered by atrial pacing, led to this current study.
Out of a population of 152 patients with dual-chamber pacemakers inserted at least one year previously, Garrigue and colleagues studied 15 patients with SAS confirmed by overnight sleep lab polysomnography. Subjects were assigned to be studied with and without overdrive pacing, set to provide a rate 15 beats per minute faster than the previously ascertained mean nocturnal heart rate in these individuals.
Overdrive atrial pacing produced a significant reduction in apnea, including a greater than 50% reduction in 13 of the 15 patients. Garrigue et al conclude that atrial overdrive pacing can effectively improve SAS in persons with pacemakers. Whether such an intervention might benefit other groups of patients, including those with no otherwise apparent indication for use of a pacemaker, remains an unanswered question.
Garrigue S, et al. N Engl J Med. 2002; 346:404-412.
Metabolic Syndrome Among US Adults
The metabolic syndrome is defined as the presence of 3 or more of 5 potential measurements : 1) abdominal obesity (waist circumference > 102 in men, > 88 cm in women); 2) hypertriglyceridemia (>150 mg/dL); 3) low HDL < 40 in men, < 50 in women); 4) BP > 130/85; and 6) fasting glucose > 110 mg/dL. Metabolic syndrome has been recognized to be associated with increased cardiovascular risk, as well as increased risk of developing diabetes and increased total mortality. The most recent guidelines on lipid management by the National Cholesterol Education Program have affirmed a new prioritization for clinicians to address the metabolic syndrome, but the current prevalence of this syndrome in America has not been heretofore determined.
The National Health and Nutrition Examination Survey (NHANES) has been operative since the 1960s, and does periodic epidemiologic reporting on an ethically diverse adult population of men and women. Information to ascertain the prevalence of metabolic syndrome is available from this 1988-1994 data set (n = 8814).
Overall, more than 1 out of 5 Americans fits the criteria for the metabolic syndrome. The frequency of metabolic syndrome increases with age, so that in persons 60-69 years old, more than 40% had metabolic syndrome. Mexican-Americans had the highest overall frequency of metabolic syndrome.
Ford ES, et al. JAMA. 2002;287:356-359.
Dr. Kuritzky, Clinical Associate Professor, University of Florida, Gainesville, is Associate Editor of Internal Medicine Alert.
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