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In a study published online and in the upcoming issue of the journal Neurology, scientists have taken a step toward developing a blood test for Alzheimer’s, finding a group of markers that hold up in statistical analyses in three independent groups of patients.

“Reliability and failure to replicate initial results have been the biggest challenge in this field,” says lead author William Hu, assistant professor of neurology at Emory University School of Medicine. “We demonstrate here that it is possible to show consistent findings.”

Hu and his collaborators at the University of Pennsylvania and Washington University, St. Louis, measured the levels of 190 proteins in the blood of 600 study participants at those institutions. Study participants included healthy volunteers and those who had been diagnosed with Alzheimer’s disease or mild cognitive impairment (MCI). MCI, often considered a harbinger for Alzheimer’s disease, causes a slight but measurable decline in cognitive abilities.

A subset of the 190 protein levels (17) were significantly different in people with MCI or Alzheimer’s. When those markers were checked against data from 566 people participating in the multicenter Alzheimer’s Disease Neuroimaging Initiative, only four markers remained: apolipoprotein E, B-type natriuretic peptide, C-reactive protein and pancreatic polypeptide.

Changes in levels of these four proteins in blood also correlated with measurements from the same patients of the levels of proteins [beta-amyloid] in cerebrospinal fluid that previously have been connected with Alzheimer’s. The analysis grouped together people with MCI, who are at high risk of developing Alzheimer’s, and full Alzheimer’s.

“We were looking for a sensitive signal,” says Hu. “MCI has been hypothesized to be an early phase of AD, and sensitive markers that capture the physiological changes in both MCI and AD would be most helpful clinically.”

“The specificity of this panel still needs to be determined, since only a small number of patients with non-AD dementias were included,” says Hu. “In addition, the differing proportions of patients with MCI in each group make it more difficult to identify MCI- or AD-specific changes.”

Neurologists currently diagnose Alzheimer’s disease based mainly on clinical symptoms. Additional information can come from PET brain imaging, which tends to be expensive, or analysis of a spinal tap, which can be painful.

“Though a blood test to identify underlying Alzheimer’s disease is not quite ready for prime time given today’s technology, we now have identified ways to make sure that a test will be reliable,” says Hu. “In the meantime, the combination of a clinical exam and cerebrospinal fluid analysis remains the best tool for diagnosis in someone with mild memory or cognitive troubles.”

Hu’s research began while he was a fellow at the University of Pennsylvania. Collaborators included David Holtzman from Washington University at St. Louis, Leslie Shawand John Trojanowski from the University of Pennsylvania, and Holly Soares from Bristol Myers Squibb.

The Alzheimer’s Disease Neuroimaging Initiative is supported by the National Institutes of Health and several pharmaceutical companies. Hu’s research is supported by the Viretta Brady Discovery Fund.

Reference: W.T. Hu et al. Plasma multianalyte profiling in mild cognitive impairment and Alzheimer disease. Neurology 79, 897-905 (2012)

 
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ᔥ Brain Pickings

Children fed healthy diets in early age may have a slightly higher IQ, while those on heavier junk food diets may have a slightly reduced IQ, according to new research from the University of Adelaide.

The study – led by University of Adelaide Public Health researcher Dr Lisa Smithers – looked at the link between the eating habits of children at six months, 15 months and two years, and their IQ at eight years of age.

The study of more than 7000 children compared a range of dietary patterns, including traditional and contemporary home-prepared food, ready-prepared baby foods, breastfeeding, and ‘discretionary’ or junk foods.

“Diet supplies the nutrients needed for the development of brain tissues in the first two years of life, and the aim of this study was to look at what impact diet would have on children’s IQs,” Dr Smithers says.

“We found that children who were breastfed at six months and had a healthy diet regularly including foods such as legumes, cheese, fruit and vegetables at 15 and 24 months, had an IQ up to two points higher by age eight.

“Those children who had a diet regularly involving biscuits, chocolate, lollies, soft drinks and chips in the first two years of life had IQs up to two points lower by age eight.

“We also found some negative impact on IQ from ready-prepared baby foods given at six months, but some positive associations when given at 24 months,” Dr Smithers says.

Dr Smithers says this study reinforces the need to provide children with healthy foods at a crucial, formative time in their lives.

“While the differences in IQ are not huge, this study provides some of the strongest evidence to date that dietary patterns from six to 24 months have a small but significant effect on IQ at eight years of age,” Dr Smithers says.

“It is important that we consider the longer-term impact of the foods we feed our children,” she says.

The results of this study have been published online in the European Journal of Epidemiology.