6 May 2002

People with Down syndrome are now living much longer. In the United States, median age at death increased from 25 years in 1983 to 49 years in 1997, with a substantial decrease in deaths before age five years. Data on all deaths for persons with Down syndrome (n = 17 897) were selected from officially compiled, multiple-cause mortality files for all deaths from 1983 to 1997, then compared with a random sample of 25% of all deaths. Standardised mortality odds ratios (SMORs) were calculated, adjusted for age, sex, race and year of birth. Death certificates for people with Down syndrome were significantly more likely to list congenital heart defects (peaking at age 20–29 years, SMOR 85.5 [95% CI, 75.9–96.4]), dementia (SMOR, 116.0 [95% CI, 93.6–143.8] at age 40–49 years), hypothyroidism, seizure disorder, aspiration pneumonia, influenza, viral hepatitis, or leukaemia.

Lancet 2002; 359: 1019-1025

Californian researchers have demonstrated that new cells in the adult mouse hippocampus mature into functional neurones. The structure of the cells could be seen by electron microscopy after they were labelled with a retroviral vector expressing green fluorescent protein (GFP), which only labels dividing cells. In mice killed after 48 hours, the GFP-positive cells were immature neurones. In those killed at four weeks, dendrites and an axon were observed, and by four months the cells were larger with more dendrites and spines, and resembled mature neurones. Electrophysiological recordings of GFP cells made after 4–8 weeks showed that the neurones were functional. New brain cells have also been observed in the adult human hippocampus. As this region of the brain is important in memory and learning, an understanding of the functional significance of these newly developed cells is keenly awaited.

Nature 2002; 415: 1030-1034

A study from Stanford University confirms the importance of fitness to survival. Peak exercise capacity was estimated during symptom-limited testing on a treadmill in 6213 men referred for clinical reasons. At age 59 years (SD, 11), 3679 men had either a history of cardiovascular or pulmonary disease or abnormal results on this test (CVS group), while 2534 were considered normal. During 6.2 years’ (SD, 3.7) follow-up, 1256 of the men died. In both groups, subjects with lower exercise capacity had a higher risk of death (for lowest v highest quintiles of exercise capacity, the age-adjusted relative risk was 4.5 for the normal group and 4.1 for the CVS group). Peak exercise capacity was the best predictor of an increased risk of death in both groups. In the normal group this was followed by pack-years of smoking and, in the CVS group, by histories of congestive cardiac failure and myocardial infarction, then pack-years of smoking.

N Engl J Med 2002; 346: 793-801

A British study suggests that the prevention of insulin resistance and its consequences may need to begin before adult life. Blood samples were collected from 73 South Asian children (mostly from Pakistan) and 1287 white children, aged 10–11 years, as part of a cross-sectional comparison of primary school children from 10 towns. Observations included height, weight, blood pressure, heart rate and waist and hip measurements. Despite similar glucose levels, insulin levels were higher in South Asian children than white children, both fasting (47.8 v 31.2 pmol/L) and 30 minutes after glucose (459.8 v 298.7; adjusted difference, 54% [95% CI, 19%–99%]). As these differences were not associated with corresponding differences in adiposity, the causes of increased insulin resistance in these South Asian children remain unclear.

BMJ 2002; 324: 1-6

An Israeli study of acute myocardial infarction (AMI) found improved survival when aspirin was given early. In an RCT, 1200 patients with AMI were commenced on thrombolytic therapy within six hours of onset of symptoms, receiving either recombinant tissue plasminogen activator or streptokinase, plus either heparin or argotroban. There were no differences in outcome between the groups. Aspirin 160 mg was to be given within one hour of starting thrombolytic therapy, then daily for 30 days. However, 364 subjects had received aspirin significantly earlier, before starting thrombolysis (1.6 v 3.5 hours). This early- aspirin group was found to have significantly lower mortality than the other patients at 7 days (2.5% v 6%), 30 days (3.3% v 7.3%) and one year (5.0% v 10.6%). In further analysis, early aspirin treatment emerged as an independent variable associated with improved survival.

Am J Cardiol 2002; 89: 381-385

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