8 August 2009

Australian study into lacunar infarcts and vascular dementia

Lacunar infarcts and vascular dementia
Alzheimer's Australia Dementia News: 6 August 2009
Lacunar infarcts are strokes of a type that result from disease that blocks arteries that penetrate into the brain's deep structures. The term ‘lacunar’ comes from the Latin for 'lake'; these infarcts are cavities that are filled with empty fluid. Lacunar infarcts are no larger than 2 cm in diameter and are often present without causing symptoms, but it is thought that they are an important part of the underlying pathology of vascular dementia. One of the ways to study the role of lacunar infarcts in vascular dementia is to undertake prospective studies within large communities. At present, the data for the incidence of lacunar infarction within large communities are scarce.

Dr Chen and colleagues from the University of New South Wales; the Prince of Wales Hospital in Sydney; and the Australian National University randomly recruited 477 people aged 60–64 years from the electoral roll to study whether they had lacunar infarcts in their brains in spite of having no symptoms.

Demographic information was gathered from participants, along with data on their risk factors, and each participant was given magnetic resonance imaging brain scans at the beginning of the study and four years later. The number and locations of lacunar infarcts were recorded along with other data on the volumes of different parts of the brain.

When the first set of brain scans was assessed, 37 (7.8%) participants were found to have at least one lacunar infarct. Four years later new lacunar infarcts were discovered in six (1.6%) participants. But the lacunas that had been found in the 37 participants at the beginning of the study had increased significantly in volume over the intervening four years.

Dr Chen and colleagues found that the factors that were independently associated with the prevalence of lacunar infarction were high blood pressure, the ratio of the volume of one of the four types of ventricles in the brain to brain volume (ventricles are important communicating cavities within the brain that are continuous with the central canal of the spinal cord. They are filled with cerebrospinal fluid, which bathes and cushions the brain and spinal cord), and white-matter hyperintensities.

White-matter hyperintensities are regions of scattered loss of brain white matter associated with local increases in brain water content. (White matter is brain tissue that contains insulated nerve fibres.) White-matter hyperintensities are abnormalities that are commonly observed in the elderly, and they generally reflect brain injury arising from blood-vessel disease. As white-matter hyperintensities accumulate, they produce substantial neurologic, psychiatric, and medical abnormalities.

Reference: Chen X, Wen W, Anstey KJ, and Sachdev PS. 2009. Prevalence, incidence, and risk factors of lacunar infarcts in a community sample. Neurology 73:266-272.

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