Journal Digest

A study published last month in Neurology shows that older people not getting enough vitamin D may be at greater risk for dementia and Alzheimer’s disease (AD) than had been estimated from previous findings.

“We expected to find an association between low vitamin D levels and the risk of dementia and Alzheimer’s disease, but the results were surprising—we actually found that the association was twice as strong as we anticipated,” commented study author David Llewellyn, Ph.D., of the University of Exeter Medical School in the United Kingdom.

Findings from the analysis, which included 1,658 individuals over age 65 who were dementia-free at the beginning of the study, showed that people with low blood levels of vitamin D had an increased risk of 53 percent for dementia and 73 percent for AD, compared with participants with normal levels of vitamin D. Furthermore, those who were severely deficient were more than 120 percent more likely to develop dementia or AD than their counterparts without a vitamin D deficiency.

Llewellyn said the current findings “do not demonstrate that low vitamin D levels cause dementia. . . . [Therefore] we need to be cautious in this early stage. That said, our findings are very encouraging, and even if a small number of people could benefit, this could have enormous public-health implications, given the devastating and costly nature of dementia.”

A study published in Nature Genetics suggests that most genetic risk for autism spectrum disorder (ASD) is derived from gene variants that are common in the population—not rare variants or spontaneous glitches.

The study, led by Swedish researchers, included genetic information on approximately 3,000 people with ASD that was compared with that of people without ASD. The results showed that about 49 percent of the total risk for ASD was traced to common inherited variations in the genetic code shared by many people, whereas rare inherited variations accounted for only 2.6 percent of the risk.

“Common variation may be more important than we thought,” stated Thomas Insel, M.D, director of the National Institute of Mental Health, which in part funded the study. “Thanks to the boost in statistical power that comes with ample sample size, autism geneticists can now detect common as well as rare genetic variation associated with risk.”

Researchers at McGill University in Montreal discovered that a genetic variant of HMG-CoA reductase—a protein involved in cholesterol synthesis—may be important in delaying the onset of Alzheimer’s disease (AD).

Using genetic information from participants with mild cognitive impairment involved in the Alzheimer’s Disease Cooperative Study and Alzheimer’s Disease Neuroimaging Initiative, the researchers investigated the association between AD and a single nucleotide polymorphism, rs3846662, in the HMG-CoA reductase gene.

Study results showed that participants who possessed the genetic variant exhibited delayed onset of AD by three to four years, compared with those without the polymorphism. The delay in onset was even sustained in patients who possessed the APOE4 allele—a trait that heightens AD risk.

The researchers said their finding is “an exciting breakthrough in a field where successes have been scarce over the past few years.”

Brigitte Kieffer, Ph.D., scientific director of the Douglas Mental Health University Institute and a professor of molecular psychiatry at McGill who was not involved in the study, commented that the results “are an important step forward in . . . [using] genetics to identify an interesting new molecular target that is amenable to therapeutic development.”

Previous studies have shown that people in the military as a whole are more likely than the general public to consume alcohol, but a new study suggests that such findings may not hold true across gender lines.

Researchers from Western Washington University surveyed nearly 9,000 individuals, born from 1980 to 1984 to compare the use of alcohol between U.S. military enlistees and veterans and the general population. Respondents were asked about their alcohol consumption in the previous 30 days.

Results showed that military men were more likely than their civilian counterparts to use alcohol. However, the opposite was true for women enlistees and veterans, who were less likely to drink than their civilian counterparts. The study also showed that regardless of gender, the longer someone served in the military the more likely they were to use alcohol.

The authors concluded that the current findings should “spur more investigation into the unique role that gender plays in the linkage between military service and alcohol use . . . [and] provide for an increased emphasis on the efforts to reduce the culture of consumption in the military” among both men and women.

Mass job layoffs in a state appear to play a role in triggering suicide-related behaviors in adults, and new research finds a similar association in some categories of teenagers as well.

Researchers at the Sanford School of Public Policy at Duke University studied the effects of mass layoffs—defined as affecting more than 50 employees at companies in a state—on suicide ideation, plans, or attempts, in a diverse population of 400,000 adolescents across the United States.

They found that when 1 percent of a state’s working-age population (those aged 25 to 64) lost their jobs, all of the suicide-related behaviors assessed in the study increased by 2 percent in girls, whereas boys were unaffected. “For girls, economic hardship appears to have worsened existing tendencies,” the authors suggested. When gender was taken out of the equation and only ethnicity and race were observed, the researchers found that job loss among at least 1 percent of a state’s working population was associated with a 2 percent to 3 percent increase in suicide-related behaviors in African-American teenagers, but no increase in white or Hispanic teenagers.

“The current finding adds to the evidence that factory closings and mass layoffs…have widespread negative effects on the communities, reaching beyond individuals who lose work,” the authors noted. They hope that their findings help clinicians identify teens who could be at increased suicide risk in economic downturns. ■