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Eight or more alcoholic drinks per week were linked to signs of injury in the brain in a large autopsy study. The finding points to changes in small blood vessels that help feed and clean brain tissue, which is hard to detect during life.

Those lesions are called hyaline arteriolosclerosis, a thickening of tiny arteries that narrows the passage for blood and stresses nearby cells.

This process sits within vascular cognitive impairment as described in an American Heart Association statement, which outlines how damaged vessels relate to thinking problems.

Alcohol and brain health

Alberto Fernando Oliveira Justo, PhD, at the University of Sao Paulo Medical School in Brazil (FMUSP) led the work. His team used human brains rather than only scans, which lets them count lesions directly and measure brain weight.

“Heavy alcohol consumption is a major global health concern linked to increased health problems and death,” said Alberto.

This project analyzed older adults who agreed to donate their organs for research, creating a window into aging and alcohol exposure.

In the United States, one standard drink contains about 14 grams of pure alcohol. That is roughly 12 ounces of beer at 5 percent alcohol, 5 ounces of wine, or 1.5 ounces of distilled spirits, which are the serving sizes researchers use to keep totals comparable across people.

The researchers classified participants as never, moderate, heavy, or former heavy drinkers based on interviews with family members.

Heavy drinking in this work meant eight or more drinks per week, a level that adds up faster than many people realize when pours are generous at home or at restaurants.

How the study was done

This cross-sectional autopsy analysis included 1,781 people with a mean age near 75 at death. All underwent standardized postmortem exams that recorded brain weight and neuropathology using standard stains to label lesions under the microscope.

Researchers looked for signs of brain damage such as tangled proteins, small strokes, buildup in blood vessels, and thickening of tiny arteries.

They also calculated a brain mass ratio by dividing brain weight by height and rated cognition using the Clinical Dementia Rating Sum of Boxes (CDR-SB) to summarize abilities close to death.

Alcohol exposure was reconstructed from detailed interviews with relatives who knew the person well. This approach is common in autopsy cohorts but it depends on memory and records kept during life.

The team used logistic and linear regression to estimate odds of lesions and differences in continuous measures.

Finally, the team tested whether vascular injury mediated any links between drinking and cognition, asking if vessel damage could explain the path from alcohol to poor scores.

Brain vessel damage from alcohol

Compared with people who never drank, the odds of hyaline arteriolosclerosis were higher in moderate drinkers, heavy drinkers, and former heavy drinkers.

Reported odds ratios were 1.60, 2.33, and 1.89 respectively with confidence intervals that excluded 1.00, which signals an association in this dataset.

For tau pathology, only heavy and former heavy drinkers showed higher odds of neurofibrillary tangles. Odds ratios were 1.41 for heavy and 1.31 for former heavy drinkers, indicating a specific link to tangles in this cohort.

Former heavy drinking tracked with a lower brain mass ratio and worse cognitive performance at the end of life.

The beta estimates were negative for mass and positive for impairment, and only former heavy status met the threshold for these outcomes after adjustment for other factors.

The association between alcohol, brain vessels, and cognitive abilities was fully mediated by hyaline arteriolosclerosis in the statistical models.

In plain terms, the vascular injury appeared to sit between reported drinking and measured cognition within this dataset.

What this might mean

When small vessels stiffen, they limit blood flow to fragile brain circuits that handle attention, speed, and memory.

Over time, injuries add up as white matter changes and microinfarcts that often go unnoticed in daily life, yet they can slow everyday tasks.

Excessive alcohol use is a leading cause of preventable deaths in the United States.

Public health estimates attribute about 178,000 deaths per year to heavy and binge patterns across the country, placing alcohol alongside tobacco and obesity among top sources of avoidable harm.

This autopsy analysis cannot prove the cause, and the authors say so. It shows a statistical signal that aligns with what pathologists and stroke specialists see in vascular cognitive impairment.

Adding alcohol to vascular risks like smoking, hypertension, or diabetes can stack the deck. Reducing intake and treating existing vascular risks could limit future small vessel injury.

Brain health, alcohol, future study

The dataset does not track how long people drank or how their habits changed across adulthood. Without a timeline, it is hard to test dose response or recovery during abstinence.

“We found heavy drinking is directly linked to signs of injury in the brain, and this can cause long-term effects on brain health, which may impact memory and thinking abilities,” said Alberto.

Alcohol reports came from informants, so misclassification can occur when records are thin or memories fade. 

These donors came from one urban region with limited formal schooling on average, which can shape both drinking patterns and health access. Future cohort studies can test whether cutting back reverses vascular stress or slows tangle buildup.

Mediation analysis isolates a pathway, but it relies on modeling assumptions.

Trials and prospective cohorts that measure alcohol objectively and track imaging and cognition could answer questions about reversibility and thresholds.

The study is published in Neurology.

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Even millimeter-level misplacements of in ovo vaccines can dramatically reduce immune response in the chick, leaving poultry flocks vulnerable to disease outbreaks despite vaccination efforts.

“Vaccination accuracy is one of the biggest determining factors of whether a vaccine is going to stimulate an immune response and therefore provide protection to that bird for the targeted diseases,” explained Dr. Josh Deines, technical service device lead at Zoetis. “When it comes to in ovo vaccination, where the vaccine is delivered within the egg significantly impacts its effectiveness.”

For example, when vaccines are accurately delivered to the embryo body or amniotic fluid, they can provide more than 93% protection against disease. However, misplaced injections into locations like the allantois reduce protection to 28% or less, while air cell injections provide virtually no protection at all.

How poultry vaccination can go wrong

The process of in ovo vaccination creates multiple potential failure points that can go unnoticed. Bent needles, one of the most common issues, can redirect vaccine placement away from target locations. Gaps in day-to-day equipment maintenance can contribute to equipment problems. For example, slipping tooling — often caused by water or sanitizer leakage onto injection heads — prevents stable positioning during the injection cycle.

Embryo development timing also plays a critical role. The acceptable transfer window ranges from 17 days, 12 hours to 19 days, 4 hours of incubation. Transferring too late reduces accuracy as embryos fill the shell and begin to hatch, increasing the risk of eye or other undesirable vaccination locations. Conversely, transferring too early or with poor incubation conditions can result in abnormally developed or mispositioned embryos.

In addition, “if there’s abnormally developed embryos mispositioned due to extreme overheating or under heating during incubation, then they may also have the vaccine delivered to the wrong location,” Deines noted.

Follow a QC checklist

Implementing a comprehensive quality control (QC) checklist can significantly improve consistency of vaccination accuracy. Key inspection points include running QC plates at the frequency recommended by the technology manufacturer to ensure every needle deposits vaccine properly, visually checking for bent needles by examining injection tooling from a 45⁰ angle and monitoring for slipping tooling throughout the injection process.

Environmental controls are equally important. Hatchery managers should avoid transferring embryos into dirty, wet or cold hatch baskets, and protect injection equipment from water leaks and excessive humidity that can compromise tooling stability.

“There’s no reason not to do it,” Deines emphasized regarding the QC checklist. “It’s such an easy task requiring little time and it can significantly impact results.”

For hatcheries processing millions of chicks monthly, even small improvements in vaccination accuracy can translate to substantial economic benefits.

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