New evidence from experimental mice further supports the idea that the early postnatal period is a critical time for establishing lifelong anxiety behaviour. The findings implicate serotonin, known to be important in mood regulation, with its agonists used therapeutically in humans as anxiolytics. American scientists had previously shown that mice bred with no serotonin-1A receptors (5-HT_1AR knockouts) were more “anxious” than wild mice on three standard tests (eg, in a novel environment they took longer to start eating). In a new transgenic mouse, it is possible to turn off the expression of these serotonin receptors at will by feeding the mouse doxycycline. Researchers found that mice fed doxycycline to switch off the receptors during the embryonic and early postnatal period developed pronounced anxiety as adults (similar to 5-HT_1AR knockouts). Mice fed doxycycline as adults were not affected.

Nature 2002; 416: 396-400

Melbourne researchers have shown, in a randomised controlled trial, that a simple behavioural intervention in babies reported to have severe sleep problems reduces both the baby’s sleep problems and the mother’s symptoms of depression. They studied 156 mothers of babies aged 6 to 12 months. Mothers being treated for postnatal depression were excluded. The intervention group received three consultations and a tailored sleep management plan (“controlled crying” in most cases), while mothers in the control group received only a letter describing normal infant sleep patterns. After two months, sleep problems had resolved in 53 of 76 infants in the intervention group, compared with 36 of 76 control-group infants. At four months, however, there was no significant difference. Maternal report of depression symptoms decreased significantly at two months, and this was sustained at four months for mothers with high depression scores.

BMJ 2002; 324: 1062-1067

Researchers in the United Kingdom have collected data which will reassure parents that the risk of their child dying as a result of food allergy is very small. From 1990 to 2000, only eight children (from a population base of 13 million) died from a food-allergic reaction. This translates to an incidence of 0.006 deaths per 100 000 children per year or, for the food-allergic child, a risk of 1 in 800 000 per year. Four of the eight deaths were reactions to milk, two to peanuts (in children aged 13 and 15), one to egg white and one to mixed food. Prospectively collected data from the last two years of the study identified 55 severe non-fatal reactions, and a strong association between coexisting asthma and reaction severity.

Arch Dis Child 2002; 86: 236-239

A large cross-sectional study of people being treated for schizophrenia has found a significant association between treatment with atypical neuroleptics and diabetes mellitus. The US Veterans Administration database was used to identify all patients with schizophrenia who had received a prescription for a neuroleptic during a four-month period, and the subgroup who also had a diagnosis of diabetes mellitus. Altogether, 22 648 (58.6%) patients had received an atypical, and 15 984 a typical, neuroleptic. Among patients younger than 60 years, but not in older age groups, those receiving atypical neuroleptics had significantly higher rates of diabetes than those receiving typical neuroleptics. In patients younger than 40 years, each of the atypical neuroleptics was associated with increased risk of diabetes (odds ratios: clozapine, 2.13; olanzapine, 1.64; quetiapine, 1.82, and risperidone, 1.51).

Am J Psychiatry 2002; 159: 561-566

Aerobic exercise reduces blood pressure in both hypertensive and normotensive subjects, according to a recent meta-analysis. The study, from the United States, identified 54 randomised controlled trials, median duration 12 weeks, conducted among a total of 2419 participants of different ethnic backgrounds and hypertensive status (mean ages, 21 to 79 years). Most trials had recruited people with sedentary lifestyles to exercise on a bike, to walk or to jog for up to 150 minutes per week. Aerobic exercise was associated with a significant reduction in mean systolic and diastolic blood pressure (–3.84 mmHg and –2.58 mmHg, respectively).

Ann Intern Med 2002; 136: 493-503

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