News Roundup: New and Noteworthy Information
The use of transdermal hormone replacement therapy (HRT) containing low doses of estrogen does not seem to increase the risk of stroke, and thus may be safer than oral tablets of HRT, researchers reported in the June 3 online BMJ. The researchers matched 15,710 women (ages 50 to 79) who had a stroke with 59,958 controls. The rate of stroke in the cohort was 2.85 per 1,000 per year, and the adjusted rate ratio (RR) of stroke associated with current use of transdermal HRT was 0.95 relative to no use. “The risk of stroke was not increased with use of low estrogen dose patches (RR, 0.81) compared with no use, whereas the risk was increased with high dose patches (RR, 1.89),” the study authors reported. “Current users of oral HRT had a higher rate of stroke than nonusers (RR, 1.28) with both low dose and high dose.”
The risk of cerebrovasular disease is higher in individuals with elevated blood pressure or fluctuations in blood pressure than those with low blood pressure or fewer fluctuations, a study in the May Archives of Neurology reported. In a community-based epidemiologic study of older adults living in the Washington Heights-Inwood section of Manhattan, researchers measured white matter hyperintensity and the presence of brain infarctions in a group of 686 nondemented older adults whose blood pressure was measured during three visits 24 months apart and who underwent structural MRIs. Participants with the lowest white matter hyperintensity volume had the lowest mean/lowest blood pressure, and those with the highest white matter hyperintensity volume had the highest mean/highest blood pressure. “Given that cerebrovascular disease is associated with disability, these findings suggest that interventions should focus on long-term fluctuating blood pressure and elevated blood pressure,” investigators concluded.
Histaminergic neurotransmission may play a role in the mechanism and modulation of Tourette syndrome and tics, researchers reported in the May 20 New England Journal of Medicine. “Despite a strong genetic contribution, inheritance is complex and risk alleles have proven difficult to identify,” the investigators noted. “We have characterized a highly unusual two-generation pedigree in which Tourette syndrome is segregated in an autosomal dominant fashion.” The researchers identified “a rare functional mutation in the HDC gene encoding L-histamine decarboxylase, the rate-limiting enzyme in histamine biosynthesis.” They added that “the links between histaminergic neurotransmission and tics, suggested by our genetic findings, are further supported by previous studies of pharmacologic agents that target the presynaptic autoreceptor H3R.”
In patients with traumatic brain injury (TBI), reduced evening melatonin production may indicate disruption to circadian regulation of melatonin synthesis and lead to sleep disturbance, as reported in the May 25 Neurology. In an observational study of 23 patients with TBI and 23 age- and gender-matched healthy volunteers, researchers found two factors contributing to sleep disturbances in patients with TBI—reduced sleep quality due to elevated depression and anxiety and increased slow wave sleep due to mechanical brain damage. “Patients with TBI reported higher anxiety and depressive symptoms and sleep disturbance than controls,” the investigators wrote. “Patients with TBI showed decreased sleep efficiency and increased wake after sleep onset.” In addition, TBI subjects had lower levels of evening melatonin production associated with REM sleep.
—Rebecca K. Abma and Colby Stong
