'By following these simple guidelines, we can maximise our memory and even defy dementia' - Trinity's Dr Sabina Brennan

Your brain is unique, crafted by the experiences that you offer it and the demands that you place on it each and every day. Your brain is a dynamic organ that not only influences your behaviour but is also influenced by your behaviour. What you do or don't do influences how well your brain functions now and how resilient it can be when faced with future challenges. Your brain is constantly changing and it is your behaviours and your experiences that shape it.

Your brain is plastic - not credit-card plastic but pliable like putty. This neuroplasticity is a fundamental feature of the human brain. It's not exclusive to humans but the human brain does appear to excel at adaptation. While genetics determine brain size in humans and chimpanzees, the human brain is more responsive to environmental influences, allowing it and its behaviour to constantly adapt to changes. We tend to afford a lot of importance to our genes, but lifestyle and life experiences are critical to determining the shape of the brain, how it grows and how it evolves. You can change your brain through experience. Learning can shape it rather like exercising can shape your muscles.

Managing stress

The goal is to find your personal stress sweet spot. You don't want too much or too little stress but just the right amount for you - a bit like Goldilocks. You can test out your stress boundaries in a variety of ways. You could just do whatever it is that is causing you stress: ask that special person in your office out on a date, go for a job interview or go to the theatre on your own. Or you can go for incremental and gradual exposure to your stressor, such as overcoming your fear of drowning by learning to swim, but do so slowly, starting with dipping a toe in the water rather than jumping in at the deep end.

10 practical tips to manage stress

1. Be excited.

2. Be active.

3. Be present.

4. Be positive.

5. Be balanced.

6. Be realistic.

7. Be practical.

8. Be interested.

9. Be happy.

10. Be connected.

Learning: the brain changer

Learning is like a powerful brain-changing drug generating new brain cells, enriching brain networks and opening new routes that your brain can use to bypass damage. Lifelong learning results in a range of positive outcomes, including reduced risk of social isolation, increased mental and social activity and improved quality of life and wellbeing.

Lifelong learning also benefits your brain health, reduces your risk of developing dementia and increases your chances of continuing to live independently in later life. The human brain was built for learning and change so that we can adapt to an ever-changing world. Your brain confers on you the ability to do tomorrow what you couldn't do today. Learning is not just for the young. Learning is for everyone. Learning is for living and learning is for life.

Loneliness is a killer

Social isolation - and especially perceived isolation - negatively impacts on health through effects on the brain, on the physiological stress response, on sleep, on blood pressure, on inflammatory processes and on the immune system. People who are lonely, who live alone or who are socially isolated have an increased risk of early death. This is most likely a consequence of the impact that social deficits have on diseases that ultimately lead to death.

Being a member of a social species comes with benefits (protection and assistance) and costs (risk of infection and competition for food and for mates). From an evolutionary perspective, being isolated from our social group can be perilous, making us vulnerable to predators.

Feelings of loneliness act as a biological warning, an alarm bell, motivating us to take action to avoid isolation. However, the brain also switches into self-preservation mode when we feel socially isolated. Changes occur in the brain, which make us more alert to danger, more distrustful and less empathetic towards others. Ironically, this can make us more likely to isolate ourselves socially. If we remain lonely, over time our social skills become eroded through disuse.

Loneliness experienced over long periods may act as a chronic stressor, increasing the activity and number of neural connections in our brain's fear centre (the amygdala), putting us on high alert and keeping us in high self-preservation mode. Loneliness doesn't just make you feel unhappy, it can make you feel unsafe and interfere with sleep, which can have a knock-on effect on health and wellbeing.

Invest in leisure

Reading, hobbies and artistic or creative pastimes can help to protect against cognitive decline. One study that well illustrates this examined whether engaging in cognitively stimulating leisure activities (reading, writing, crosswords, board/card games, discussions and playing music) in later life could affect the trajectory of memory decline. Over the course of the study 101 of the 488 participants developed dementia. In the people who had developed dementia, each additionalday that they engaged in the leisure activities delayed the onset of accelerated memory decline for two months.

Having billions of neurons means that your brain is the most energy-demanding organ in your body. Your brain only weighs about 2pc of your body but uses 20-25pc of your body energy every day just to keep your brain working. Based on the Brazilian brain soup count, it costs six calories to run one billion neurons, that's 514 calories out of your 2,000-calorie daily entitlement just to keep your 86 billion neurons ticking over.

Your brain consumes a lot of oxygen and nutrients and needs to be constantly informed of your body's needs and available resources. It depends on its vast neuronal networks to provide that information. Your ability to learn, think and remember is closely linked to your glucose levels and the ability of your brain to efficiently use this energy source. Your brain health is very much linked to heart health and to the health and integrity of the blood vessels that carry the oxygen and nutrients around your body and your brain. Your brain needs oxygen to thrive and cannot survive for more than a few minutes without it. This is one of the reasons why exercise is critical for brain health.

When you start exercising, the blood flowing to your brain carries extra oxygen and nutrients to your neurons. It seems your brain is poised to take advantage of this and we think that the increase in oxygen may help to stimulate the production of new nerve cells (neurogenesis).

10 practical tips to get physically active

1. Exercise every day.

2. Safety first.

3. Sit less.

4. Stand more.

5. Straighten up.

6. Move more.

7. Swap some screen time for active hobbies.

8. Strength and balance.

9. Rest and recovery.

10. Play.

How does attitude impact brain health?

Memory processing can be enhanced by reward. When we see a smiling face it feels rewarding to us. We can quickly recall the names of people who smile. This enhanced memory for smiling faces occurs because of the effect that your brain's reward regions have on memory regions.

The reward system in the brain evolved to motivate us to engage in behaviours such as eating food, drinking water and having sex - activities that keep us alive and promote the survival of our species. To enhance survival, the reward system in the human brain drives desire, craving and motivation, triggering positive emotions like pleasure to maximise our interactions with things that benefit us.

When you eat something, let's say a 'triple-decker sandwich', neurons in a specific area of your brain involved in reward release the neurotransmitter dopamine, giving you a surge of pleasure. To ensure that you will repeat this 'eating' behaviour the reward centres in your brain are connected to the areas in your brain that control memory and behaviour. Remembering that eating that sandwich made you feel good will make you more likely to eat it again.

The brain also needs to minimise our interaction with things that can cause us harm. The fear system in the human brain evolved to keep us safe. There is overlap between the reward and fear networks in your brain. At the most fundamental level, through the activation of these systems you feel fear and you learn associations so that your behaviours are incentivised, conditioned, reinforced, rewarded and/or punished. This means that you are likely either to approach or avoid food, things, objects, events, people, activities and situations depending on whether they have given you pleasure or pain.

Cherish your sleep

You don’t need me to tell you that sleep is essential. You know only too well that if you don’t get enough sleep you become irritable and you can’t think straight — in fact, pretty much all you can think about is getting some sleep. You need sleep. Your brain needs sleep. Your body needs sleep. Sleep is fundamental not just for brain health but also for physical and mental health.

10 practical tips to cherish sleep

1. Go to bed and get up at the same time each day.

2. Unwind and create a calming bedtime ritual.

3. Manage light exposure.

4. Create a sleep haven.

5. Get physically active during the day.

6. Quit smoking.

7. Avoid caffeine in the evenings.

8. Avoid alcohol close to bedtime.

9. Manage conditions or medications that impact on sleep quality.

10. Manage stress.

Extracted from 100 Days To A Younger Brain by Dr Sabina Brennan, published by Orion Spring at £16.99