Temporal Cognitive Decline Associated With Exposure to Infectious Agents in a Population-based, Aging Cohort. - PubMed - NCBI

 "Numerous cross-sectional studies have related exposure to neurotropic infectious agents with cognitive dysfunction in older adults, however, the temporal sequence is uncertain.

METHODS:
In a representative, well-characterized, population-based aging cohort, we determined whether the temporal trajectories of multiple cognitive domains are associated with exposure to cytomegalovirus (CMV), Herpes Simplex virus, type 1 (HSV-1), Herpes Simplex virus, type 2 (HSV-2), or Toxoplasma gondii (TOX). Complex attention, executive functions, memory, language, and visuospatial function were assessed annually for 5 years among consenting individuals. Study entry IgG antibody titers indexing exposure to each infectious agent were examined in relation to slopes of subsequent temporal cognitive decline using multiple linear regressions adjusted for potential confounders.

RESULTS:
The IgG levels for HSV-2 were significantly associated with baseline cognitive domain scores (N=1022 participants). Further, the IgG levels for HSV-2, TOX, and CMV, but not HSV-1 were significantly associated with greater temporal cognitive decline that varied by type of infection.

CONCLUSIONS:
Exposure to CMV, HSV-2, or TOX is associated with cognitive deterioration in older individuals, independent of general age-related variables. An increased understanding of the role of infectious agents in cognitive decline may lead to new methods for its prevention and treatment."



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Algae Virus Found in Healthy Human Throats

 Scientists from Johns Hopkins and the University of Nebraska have
discovered an algae virus never before seen in the throats of healthy
people that may subtly alter a range of cognitive functions including
visual processing and spatial orientation in those who harbor it. A
report on the team’s findings is published online in Proceedings of the National Academy of Science.
Yolken and colleagues stumbled upon the algae virus unexpectedly

while analyzing the microbial population of the throats of healthy
humans for a non-related study. Investigators obtained throat swabs and
performed DNA analysis designed to detect the genetic footprints of
viruses and bacteria. To their surprise, the researchers say, they
discovered DNA matching that of Acanthocystis turfacea Chlorella virus
1, or ATCV-1, known to infect green algae. Green algae include more than
7,000 water-dwelling organisms that resemble plants but belong to a
separate biologic kingdom. They are commonly found in aquatic
environments like ponds, lakes and the ocean.

 Forty of 92 participants in the study tested positive for the algae

virus. The group that harbored the virus performed worse overall on a
set of tasks to measure the speed and accuracy of visual processing.
While their performance was not drastically poorer, it was measurably
lower, the researchers said. For example, people who harbored the virus
scored, on average, nearly nine points lower on a test that measured how
quickly they could draw a line between sequentially numbered circles on
a piece of paper. Viral carriers also scored seven points lower, on
average, on tests measuring attention.

To further elucidate the effects of the virus, the investigators
infected a group of mice and analyzed their performance on a set of
tests designed to measure the rodent equivalent of human cognitive
function. Animals infected with the virus exhibited deficits similar to
those observed in humans. Infected animals had worse recognition memory
and spatial orientation than uninfected mice. 

Influenza infection induces neuroinflammation, alters hippocampal neuron morphology, and impairs cognition in adult mice.

Influenza is a common and highly contagious viral pathogen, yet its effects on the structure and function of the CNS remain largely unknown. Although there is evidence that influenza strains that infect the brain can lead to altered cognitive and emotional behaviors, it is unknown whether a viral strain that is not neurotropic (A/PR/8/34) can result in a central inflammatory response, neuronal damage, and neurobehavioral effects. We hypothesized that neuroinflammation and alterations in hippocampal neuron morphology may parallel cognitive dysfunction following peripheral infection with live influenza virus. Here, we show that influenza-infected mice exhibited cognitive deficits in a reversal learning version of the Morris water maze. At the same time point in which cognitive impairment was evident, proinflammatory cytokines (IL-1β, IL-6, TNF-α, IFN-α) and microglial reactivity were increased, while neurotrophic (BDNF, NGF) and immunomodulatory (CD200, CX3CL1) factors were decreased in the hippocampus of infected mice. In addition, influenza induced architectural changes to hippocampal neurons in the CA1 and dentate gyrus, with the most profound effects on dentate granule cells in the innermost portion of the granule cell layer. Overall, these data provide the first evidence that neuroinflammation and changes in hippocampal structural plasticity may underlie cognitive dysfunction associated with influenza infection. In addition, the heightened inflammatory state concurrent with reduced neurotrophic support could leave the brain vulnerable to subsequent insult following influenza infection. A better understanding of how influenza impacts the brain and behavior may provide insight for preventing inflammation and neuronal damage during peripheral viral infection.

Neglected Babies Develop Less Myelin | The Scientist

Isolating mouse pups from their mothers early in development can reduce the insulation surrounding neurons of the brain, which leads to problems with memory and socialization, a study in Science reported last week (September 14). The study provides a molecular explanation for the cognitive deficits observed in children raised in orphanages where they are rarely touched

Prenatal exposure to insecticide chlorpyrifos linked to alterations in brain structure and cognition

Even low to moderate levels of exposure to the insecticide chlorpyrifos during pregnancy may lead to long-term, potentially irreversible changes in the brain structure of the child, according to a new brain imaging study by researchers from the Columbia Center for Children's Environmental Health at the Mailman School of Public Health, Duke University Medical Center, Emory University, and the New York State Psychiatric Institute. The changes in brain structure are consistent with cognitive deficits found in children exposed to this chemical.