A new study from the University of Southern California, involving 8,500 children from across the USA, has revealed that a form of air pollution, largely the product of agricultural emissions, is linked to poor learning and memory performance in 9 and 10 year-olds.

Ammonium nitrate Is the specific component of fine particle air pollution (PM2.5).  It, is also implicated in Alzheimer’s and dementia risk in adults, suggesting that PM2.5 may cause harm to brain function across the lifespan. Ammonium nitrate forms when ammonia gas and nitric acid, produced by agricultural activities and fossil fuel combustion, respectively, react in the atmosphere.

PM2.5: A danger to the lungs

PM2.5, a key indicator of air quality, is a mixture of dust, soot, organic compounds and metals that come in a range of particle sizes less than 2.5 micrometers in diameter. PM2.5 can travel deep into the lungs, where these particles can pass into the bloodstream, and bypass the blood-brain barrier, causing serious health problems.

Fossil fuel combustion is one of the largest sources of PM2.5, especially in urban areas, but sources like wildfires, agriculture, marine aerosols and chemical reactions are also important.

In 2020, an earlier study did not find a relationship between PM2.5 as a whole, and its potential impact on cognition in children. For this study, however, they used special statistical techniques to investigate 15 chemical components in PM2.5 and their sources. That’s when ammonium nitrate—which is usually a result of agricultural and farming operations—in the air appeared as a prime suspect.  The most robust finding was that ammonium nitrate particles were linked to poorer learning and memory.

 More information: Kirthana Sukumaran et al, Associations between Fine Particulate Matter Components, Their Sources, and Cognitive Outcomes in Children Ages 9–10 Years Old from the United States, Environmental Health Perspectives (2024). DOI: 10.1289/EHP14418

Journal information: Environmental Health Perspectives 

 

Provided by Leigh Hopper, University of Southern California 

Image provided by Freepik

 

Martin Doherty, writing for The Conversation, says that at the age of about four, children reach important milestones in brain development.

One of these is a huge improvement in understanding others’ thoughts and feelings. This is the start of empathy.  Another is in spatial thinking—understanding how objects are positioned and related. This is the beginning of the ability to read maps.

Martin and his colleague, Catherine Sayer, conducted a study with 175 two to five-year-olds to explore how children are able to use scale models to figure out where something is in the real world. At about four, children are able to use a scale model of a room to work out where something is. We thought that this might result from children’s understanding of how one thing can represent something else. But we actually found that four-year-olds’ ability to use scale models came from their spatial abilities.

At the same age, children start to understand that someone’s behaviour is due to what that person believes, not necessarily what is really the case. This has interesting consequences.

If you’ve played hide-and-seek with young children, you may have noticed that they aren’t always very good at it. They love the ritual of looking in all the wrong places first, but beforehand they may tell you where they are going to hide, hide in the same place every time, or not be especially hidden.

After their fourth birthday, they get much better at hide and seek. They understand that the seeker looks in the wrong places because they don’t know where the hider is.

At about three to four children also start to tell lies. They realize they can make someone believe something that isn’t true.

Understanding symbols

Martin’s earlier research with fellow psychologist Josef Perner suggests that four-year-olds don’t just start to understand how others’ minds work. Figuring this out is part of the development of an understanding of “representation”—that symbols, like thoughts, words, or pictures, can be used to stand for something else.

Children start to think about how words relate to objects. This means, for instance, knowing that “animal” can refer to something you already have a name for, such as “rabbit”. This might help children learn the new word.

Their ability to use a understand the components of pictures also improves around this age. Very young children use a lot of trial and error to complete a jigsaw, picking up random pieces to see if they fit. By the time they are about four years old, they start to use the picture as a guide, trying to connect lines and match bits of colour, while checking the guide picture on the box lid.

Developmental experiments

Another ability children develop at around four is using scale models. A classic set of developmental experiments involved a model of a regular household room. The real room had typical furniture—sofa, table, cupboard and so on—and the model had miniature versions laid out in the same way.

Children were shown where something was hidden in the model and told to find an object hidden in “the same place” in the room. Children of around four can find the object using the identical layouts. If shown a sticker under a particular chair in the model room, for example, they can go straight to the “same” chair in the other room. This is the fundamental understanding required to read maps.

Adults see scale models and maps as representations. Maps represent a town or a country. A scale model of, say, the Eiffel Tower represents the real thing. At first, Martin suspected children’s ability to use scale models is more evidence of understanding representation at this age.

He was wrong. Instead, the researchers found that this ability is based on a development in children’s spatial abilities that also occurs at about four. This is the ability to think about spaces and where objects are within them. Spatial abilities help with maths skills, and good spatial ability is linked to an interest in science, technology, engineering and mathematics.

Their experiment was simple. They compared the model room task with a test of understanding how representation works. The two abilities develop around the same age, but they found they were not related. Children who could do one task couldn’t necessarily do the other.

They also had a test of purely spatial ability. Children who passed the model room task also passed the spatial task. So it looks like the model room task relied on children‘s spatial thinking.

They don’t yet know why two important but apparently unrelated abilities arise at the same time. Perhaps it’s related to changes in the growing brain at this  interesting age.

Provided by The Conversation

Image supplied by Freepik.