Neuroplasticity is the term that describes how the pathways and connections in the brain change through experience. When we practice something, the brain adapts, and we tend to become better at that skill.
When you do a sudoku puzzle every day and find you get faster ... unfortunately this doesn't mean you are getting any smarter.
If there's a particular skill you want to improve, you're probably better off practicing that skill.
Verdict: Not really (the high quality evidence suggests it isn't)
Stress is bad for you right? Well, not necessarily. The devil is in the dose, and how you perceive the stress.
A small burst of stress, such as the rush you get when you run a race, is really good for your body, helping you perform at your best.
The adrenaline kick from a stressful moment supercharges your focus, so you can attend to the task at hand and do it well. Evidence shows that the way you perceive stress is important too.
A Harvard study showed that if you view the signs of stress — such as a pounding heart or sweating — as signs your body is preparing you to meet the challenge, not only will your performance improve significantly, but the impact that stress has on your body is lessened as well.
On the other hand, long-term stress, the kind that lasts for months to years, such as when you are a carer, or dealing with job insecurity, wreaks havoc on your body, and can change — or even shrink — your brain.
Neurons in the brain's memory centre, known as the hippocampus, may become disconnected, making it harder to remember events. Stem cells start eating themselves, making the hippocampus shrink.
Chronic stress makes us adjust to a hypervigilant and reactive state.
The emotion centre of the brain, known as the amygdala, grows in size as it increases its connectivity with other neurons, making you more emotional and reactive than you otherwise would be.
And lastly, there is increasing disconnect with the prefrontal cortex, the decision-making part of your brain, making it harder to make clear judgements about a situation.
While the pressures of modern society may mean you are not always able to avoid stressful situations, you can reframe how you respond to them, as well as reduce the effects of stress on the brain with some of the following activities.
Verdict: A bit is good, a lot is bad
Meditation and mindfulness
Ever wonder why monks have such a sense of joy and calm? Meditation and mindfulness may have a lot to do with it.
We used to think of meditation as being a bit of semi-spiritual pseudoscience. Until recent years, little was known about how a few hours of quiet contemplation each week could affect us.
It has become clear that meditation has some potent effects on your body — especially your brain.
Meditation and mindfulness doesn't just reduce the levels of stress hormones (and therefore the impact stress has on your brain), but it also helps shrink your amygdala, therefore reducing your emotional reactivity
As the amygdala reduces in size, the prefrontal cortex — the brain's decision-making region — increases in thickness. This means you become less driven by your more primitive emotional reactions, and become much more decisively thoughtful.
Through its tangible effects on improving attention (and therefore an increased ability to choose which positive thoughts to focus on), meditation can bring a great feeling of joy and contentment.
But this is not the most remarkable effect exercise has on the brain.
For a long time, it was thought that we had a set number of brain cells. However, research has since shown that the brain contains stem cells — and stem cells have the ability to make new neurons in a process called neurogenesis.
Exercise also promotes the release of brain-derived neurotrophic factor, which is a bit like a fertiliser for the brain: it supports the growth of new neurons and increases neuroplasticity, making it easier for the brain to grow new connections between neurons.
Exercise also makes your brain release endorphins, the feel-good hormones, and endocannobinoids, which activates your brain's reward system and helps relieve pain.
This is why you might feel so elated after a run. These brain chemicals are also responsible for the "runners high" or "second wind" experienced during endurance exercise.
So what is the optimal amount of exercise? While varying types, intensities and lengths of exercise have been studied, 30 minutes of aerobic exercise (think heart-pumping, sweating), five times a week, is a great minimum level to work towards.
So if you're getting some, good for you — and your brain.
After we reach the age of 40, the brain shrinks by about 5 per cent each decade. This sounds troubling, but if you look after your brain health through exercise, sex, meditation and mindfulness, then you are setting yourself on the right track to live with a healthy brain, longer.
So sudoku fans, maybe you want to put the pencils away and pick up your joggers instead.