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In This Issue of JAMA Neurology
September 2017


JAMA Neurol. 2017;74(9):1023. doi:10.1001/jamaneurol.2016.4014

Residing as an adult in the southern part of the United States in the so-called Stroke Belt is associated with greater incidence of health problems, such as hypertension, diabetes, stroke, and cognitive impairment. Using an observational cohort of 7423 members of a health care system in Northern California, Gilsanz and coauthors attempted to determine if incident dementia rates are elevated in individuals who lived in the Stroke Belt in early life and moved away to other areas of the country. Dementia risk was approximately 28% higher among those born in states with high stroke mortality rates compared with members born elsewhere. Compared with nonblack persons born outside of high stroke mortality states, black individuals born in a high stroke mortality state had the highest dementia risk, followed by black individuals not born in a high stroke mortality state and by nonblack persons born in a high stroke mortality state. These findings suggest that racial/ethnic inequalities in dementia may partially reflect geographic patterning of early-life exposures. Editorial perspective is provided by Lackland.

Editorial and Continuing Medical Education

Traumatic brain injury (TBI) is increasingly common in the United States, with more than 3.5 million persons annually seeking treatment. However, we lack a prognostic and diagnostic biomarker for TBI. Rubenstein and coauthors analyzed the correlation between plasma hyperphosphorylated tau protein (P-tau) and total-tau (T-tau) levels with TBI, TBI severity, neuroimaging, and patient outcomes in 196 patients with acute TBI admitted to 3 level I trauma centers and 21 patients with TBI admitted to inpatient rehabilitation units. Single time point plasma samples from the TRACK-TBI Pilot study were assayed for P-tau (P-Thr231 epitope) and T-tau using a laser-based immunoassay. The authors reported that plasma P-tau levels and P-tau–T-tau ratio not only outperformed T-tau as diagnostic and prognostic biomarkers for acute TBI but also, in contrast to T-tau, showed prolonged elevations among patients with chronic TBI. Editorial perspective is provided by Goldstein and McKee.


In this population-based cohort study of 458 patients (287 men [62.7%]; mean age, 80.6 years) from the Mayo Clinic Study of Aging, Mielke and coauthors examined if plasma total tau was a prognostic marker for cognitive decline and risk of mild cognitive impairment or dementia and if these associations differed by elevated brain amyloid β. The authors showed that high plasma total tau was indeed associated with cognitive decline and risk of mild cognitive impairment, but elevated brain amyloid β was not a confounder or effect modifier of any outcome. These results suggest that plasma total tau may be a prognostic risk factor or biomarker for cognitive decline but is not an Alzheimer disease–specific biomarker.

Although fibromuscular dysplasia (FMD) is often asymptomatic and uncommon, some data suggest an association between FMD and an increased risk of intracranial aneurysms (IA). In a cross-sectional registry study of 1112 female patients, there were 669 women (60.2%) 18 years or older who were diagnosed as having FMD and who had undergone intracranial imaging at or before enrollment. Lather and coauthors found that IA was more common in patients with FMD than in the general population; 86 of 669 participants (12.9%) had more than 1 IA, and IAs 5 mm or larger were observed in 32 of 74 patients (43.2%). These findings suggest that noninvasive screening for IA in patients with FMD should be considered.