New Zealand scientists have helped develop an internationally groundbreaking tool that estimates a person’s risk of getting dementia and other age-related diseases.
It uses a single MRI scan that can be done in mid-life and before someone is showing any signs of the conditions.
Otago University scientists worked with Duke and Harvard universities in the United States and have published their findings in the prestigious medical journal Nature Aging this week.
Data from Otago’s Dunedin Study – which has followed 1037 participants since they were born in 1972 and 1973 – has been critical in the work.
That study looked at changes in blood pressure, glucose and cholesterol levels, tooth and gum health and other body functions over 20 years to see how quickly people were ageing.
That data was then compared with an MRI taken when the study participants were 45 and a tool – an algorithm known as Dunedin PACNI – was developed that can look at anyone’s MRI and estimate how they might age.
Dunedin Study director Professor Moana Theodore said study members who had higher or faster PACNI scores were more likely to have poorer health.
“And also poorer physical functioning, things like walking and balance, and also poorer cognitive function, things like poorer memory even though they were, at that stage in their mid 40s,” she said.
The new tool was then tested out on 50,000 brain scans from data on people aged 50-89 in other parts of the world.
“In those studies of older people we were able to identify things like the development of chronic disease, so, an increased likelihood of heart attacks or strokes, an increased risk of being diagnosed with dementia over time and even an increased mortality,” she said.
The study found those who were ageing faster had more shrinkage in the hippocampus region of the brain and performed worse on cognitive tests.
Professor Theodore said the tool could help change outcomes for people.
“If we can predict ageing, especially in mid-life…. then what we are able to do is prevent, possibly intervene earlier on to stop or slow down age related diseases like dementia for which there is currently no clear treatment,” she said
She and her team were incredibly proud of the work – and she thanked the Dunedin Study members and their families for their 50 year contribution.
“It’s wonderful to have a New Zealand study that is at the forefront of international research on ageing and how to support people to age positively and well and how to reduce age related diseases that cause people to have poorer quality of life later in life,” she said.
DunedinPACNI will be freely available for scientists around the world to use to further their own work on ageing.
This post is about a Worksheet (below) that teachers can use in the first week or two of the course to introduce students to the 6 big Concepts of the course and to allow a conversation about the significance of good research. The worksheet includes a very recent article from BBC News (June 20th, 2025) and a collection of activities for students to complete, perhaps in small groups, perhaps individually, perhaps for homework…
The birth order theory
Is the first-born always the responsible one and the last born always the fun-loving rebel?
The birth order theory suggests that your position in the family (firstborn, middle child, youngest, or only child) shapes your personality in predictable ways:
Firstborns are said to be more responsible and achievement-focused.
Middle children are often described as peacemakers or attention-seekers.
Youngest siblings are thought to be fun-loving and rebellious.
Only children are sometimes stereotyped as selfish or overly mature.
These ideas are fun to talk about at dinner tables — and even show up in TV shows and social media memes — but do they hold up to scientific scrutiny?
The research says… no.
Decades of research have tried to pin down whether birth order really causes differences in personality. While some studies have found small patterns — for example, that firstborns might score slightly higher on intelligence tests — larger and better-designed studies have found no consistent, universal effects of birth order on broad personality traits.
That doesn’t mean birth order has zero impact. It may shape behaviour in specific family contexts or cultures, and people’s beliefs about birth order can shape their identities. But overall, there’s very little evidence to say that your position in the family determines your personality in any reliable or scientific way.
This example gives us a good way to start understanding the six key Concepts of IBDP Psychology:
1. Bias
We tend to notice evidence that confirms our expectations and ignore what doesn’t — a classic example of confirmation bias. If your older sister is bossy, you might say “Well, obviously, she’s the eldest.” But what about all the bossy youngest children?
2. Causality
Is it really birth order that causes certain traits? Or could it be age, parenting style, socioeconomic status, or even gender expectations? Psychology often grapples with correlation vs. causation, and birth order is a great example of that complexity.
3. Measurement
How do we measure personality? Many studies rely on self-report questionnaires, which come with limitations. People might describe themselves based on how they think they’re supposed to behave as an oldest child, not how they actually behave.
4. Perspective
The impact of birth order may differ between cultures and families. In some societies, firstborns may carry traditional responsibilities, while in others, birth order is far less significant. Perspective reminds us that psychology is not one-size-fits-all.
5. Change
Your personality and family roles can shift over time. A younger sibling might become more responsible later in life. Psychology recognises that behaviour and identity are not fixed, but dynamic.
6. Responsibility/Ethics
If we assume someone’s behaviour is fixed by their birth order, that can be limiting — even harmful. Ethical psychology considers the social consequences of labelling, stereotyping, and drawing broad conclusions from incomplete evidence.
In the first week of IB Psychology, we’ll use this birth order debate to practice:
Asking critical questions about theories and research
Exploring the six Concepts in real-world contexts
Discussing beliefs vs. evidence, and developing a scientific mindset
You’ll be using the attached worksheet to guide your thinking and conversation. Don’t worry — you don’t need to be an expert in Psychology yet. The goal is to start asking smart questions and learning how to evaluate claims, whether they’re in a textbook, a TikTok post, or a family argument at dinner.
Final Thought
What is your birth order? (First-born, middle child, youngest, only child, twin, etc.)
Do you think your birth order has influenced your personality or behaviour? If so, in what ways?
Do people ever describe you using “birth order” traits? (e.g. “You’re such a responsible oldest child” or “Typical youngest!”) Do you agree or disagree with those descriptions?
How are your siblings’ personalities different from yours? Do you think these differences are because of birth order, or something else?
Do you think all first-borns are more responsible? All youngest siblings more fun or rebellious? Why or why not?
Do you think people act a certain way because of their birth order — or because they believe birth order affects their behaviour? Can belief shape personality?
Do cultural or family expectations influence how children behave based on their birth order? Can you think of an example?
Have you ever changed your role in the family over time? For example, were you once the “quiet one” but became more assertive? What caused that change?
Do you think only children are different from children with siblings? In what ways, and why?
If someone knew nothing else about you except your birth order, what might they assume about your personality? Do you think they’d be right?
These questions can lead to some rich and open discussion — and they provide a natural bridge into critical thinking, the importance of evidence-based research, and the limitations of generalisations in psychology.
Psychology is full of ideas that sound right — but part of becoming a psychologist is learning to dig deeper. The birth order theory may not be strongly supported by data, but it gives us the perfect launchpad into the skills, attitudes, and concepts that define this course.
Every year, I tell my students that sleep is just as important as revision and study habits when it comes to academic performance. And now, a compelling new study from the University of Cambridge and Fudan University gives us even more reason to double down on that message.
In a study involving over 3,000 teenagers, researchers discovered that those who:
Went to bed earlier,
Slept longer,
And had lower sleeping heart rates,
scored significantly higher on a range of cognitive tests, including reading, vocabulary, and problem solving.
Even more striking? The actual difference in sleep duration between groups was minimal—just 15 minutes between the lowest and highest scoring groups—yet this small variation had a surprisingly large impact on brain performance and function.
Brain scans revealed that teens with the best sleep habits not only performed better but also had larger brain volumes and more efficient brain function.
Despite these findings, even the best-sleeping teens in the study didn’t reach the 8–10 hours per night recommended by the American Academy of Sleep Medicine. The healthiest group averaged just seven hours and 25 minutes of sleep.
Why? Teenagers face a biological shift toward later bedtimes during adolescence. Add in screen use, homework, social media, and caffeine—and you’ve got a generation of students consistently underslept.
We’re not powerless. In fact, this is where we shine. As Psychology teachers, we can…
1. Teach the Science of Sleep
Incorporate sleep research into your lessons on cognitive development, memory, and mental health. Use this new study to show how even small changes in sleep patterns make a real difference.
2. Debunk Myths
Help students understand that “catching up” on weekends (aka social jet lag) doesn’t undo the damage of sleep loss during the week. Emphasize consistency.
3. Promote Simple, Practical Changes
Share strategies backed by experts:
Encourage regular exercise to improve sleep quality.
Urge students to limit screens an hour before bedtime.
Support healthy bedtime routines, such as winding down with a book, journaling, or light stretching.
4. Embed Sleep into Pastoral Care
Work with your school’s wellbeing or pastoral team to create sleep hygiene workshops, or add sleep content into personal and social education. Oxford’s Teensleep project is a great resource for ideas and activities.
5. Make Sleep “Cool”
Reframe sleep as a performance enhancer. Better memory. Sharper thinking. Bigger brains. It’s the one lifestyle change that benefits everything from academics to mental health—and it doesn’t cost a thing.
Professor Barbara Sahakian, who co-led the study, put it best: “It’s the sleep driving the better cognitive abilities… Small differences in sleep amounts accrue over time to make a big difference in outcomes.”
Let’s empower our students to make those small changes—because every extra minute of quality sleep could mean a stronger brain, clearer thinking, and greater wellbeing.
Tom Coster - Psychology 