New and Noteworthy Information—January 2016
In patients with mild Alzheimer’s disease, moderate alcohol consumption (ie, two to three units per day) is associated with a significantly lower mortality over a period of 36 months, according to a study published December 11 in BMJ Open. Investigators examined data collected as part of the Danish Alzheimer’s Intervention Study (DAISY). Information about current daily alcohol consumption was obtained from 321 study participants. In all, 8% abstained from drinking alcohol, 71% drank alcohol occasionally, 17% had two to three units per day, and 4% had more than three units per day. Mortality was not significantly different in abstinent patients or in patients with an alcohol consumption of more than three units per day, compared with patients drinking one or less than one unit per day.
Stress is a potentially remediable risk factor for amnestic mild cognitive impairment (aMCI), according to a study published online ahead of print December 10 in Alzheimer Disease & Associated Disorders. The Perceived Stress Scale (PSS) was administered annually in the Einstein Aging Study to participants age 70 and older who were free of aMCI and dementia at baseline PSS administration and who had at least one subsequent annual follow-up. Cox hazard models were used to examine time to aMCI onset, adjusting for covariates. High levels of perceived stress were associated with a 30% greater risk of incident aMCI, independent of covariates. Overall, understanding the effect that perceived stress has on cognition may lead to intervention strategies that prevent the onset of aMCI and Alzheimer’s-related dementia, said the investigators.
Heptachlor epoxide, a pesticide, is associated with higher risk for signs of Parkinson’s disease, according to a study published online ahead of print December 9 in Neurology. For the study, 449 Japanese-American men with an average age of 54 were followed for more than 30 years and until death in the Honolulu-Asia Aging Study. Tests determined whether participants had lost brain cells in the substantia nigra. In 116 brains, researchers also measured the amount of heptachlor epoxide residue, which was present at high levels in Hawaii’s milk in the early 1980s. Nonsmokers who drank more than two cups of milk per day had 40% fewer brain cells in the substantia nigra than people who drank less than two cups of milk per day.
An in vivo florbetapir PET study confirms previous postmortem evidence showing an association between Alzheimer’s disease pathology and gait speed, and provides additional evidence on potential regional effects of brain β-amyloid on motor function, according to data published online ahead of print December 7 in Neurology. Cross-sectional associations between brain β-amyloid, as measured with [18F]florbetapir PET, and gait speed were examined in 128 elderly participants. Researchers found a significant association between β-amyloid in the posterior and anterior putamen, occipital cortex, precuneus, and anterior cingulate and slow gait speed. A multivariate model emphasized the posterior putamen and the precuneus. The β-amyloid burden explained as much as 9% of the variance in gait speed and significantly improved regression models that contained demographic variables, BMI, and APOE status.
Blast-related injury and loss of consciousness are common in traumatic brain injury (TBI) that is sustained while in the military, according to a study published online ahead of print December 15 in Radiology. Study participants were military service members or dependents recruited between August 2009 and August 2014. There were 834 participants with a history of TBI and 42 participants in a control group without TBI. MRIs were performed at 3 T, primarily with three-dimensional volume imaging at voxels smaller than 1 mm3. In all, 84.2% of participants reported one or more blast-related incidents, and 63.0% reported loss of consciousness at the time of injury. White matter T2-weighted hyperintense areas were the most common pathologic finding and were observed in 51.8% of TBI participants.
Researchers have created a transgenic mouse models of familial amyotrophic lateral sclerosis (ALS), according to research published in the December 2 issue of Neuron. To investigate the pathologic role of C9ORF72 in ALS and frontotemporal dementia (FTD), researchers generated a line of mice carrying a bacterial artificial chromosome containing exons one to six of the human C9ORF72 gene with approximately 500 repeats of the GGGGCC motif. The mice showed no overt behavioral phenotype, but recapitulated distinctive histopathologic features of C9ORF72 ALS/FTD, including sense and antisense intranuclear RNA foci and poly(glycine-proline) dipeptide repeat proteins. Using an artificial microRNA that targets human C9ORF72 in cultures of primary cortical neurons from the C9BAC mice, investigators attenuated expression of the C9BAC transgene and the poly(GP) dipeptides.
Oxidative stress may underlie most of the migraine triggers encountered in clinical practice, according to a study published online ahead of print December 7 in Headache. Investigators searched the literature for studies of common migraine triggers published between 1990 and 2014. The reference lists of the resulting articles were examined for further relevant studies. In all cases except pericranial pain, common migraine triggers are capable of generating oxidative stress. Mechanisms include a high rate of energy production by the mitochondria, toxicity or altered membrane properties of the mitochondria, calcium overload and excitotoxicity, neuroinflammation and activation of microglia, and activation of neuronal nicotinamide adenine dinucleotide phosphate oxidase. For some triggers, oxidants also arise as a byproduct of monoamine oxidase or cytochrome P450 processing, or from uncoupling of nitric oxide synthase.
