Sister Bernadette had a fine mind which she enjoyed putting to work with puzzles, debating social issues, and teaching the young. She kept lively until her death at 85. As part of an ongoing study by American epidemiologists, she was one of 600 nuns who donated their brains to science. Soon before her death she continued to score in the ninetieth percentile on cognitive tests. Yet when she was examined post mortem, massive destruction from Alzheimer’s was evident. Her brain was filled with the disease’s characteristic rigid plaques and messy tangles. From the inner hippocampus (the central train station for learning, stress and mood management pathways) to the outer cortex, there was the most extensive degree of damage. So why did she remain so sharp?

The study’s lead researcher David Snowdon wrote of his surprising findings in Aging with Grace. He suggests the notion of ‘cognitive reserve’. The brain is potentially adaptive enough to compensate for damage by enlisting other areas to assist with tasks not usually their priority. By staying physically, mentally and socially active you can retain and grow more of the brain circuits linked to memory, acuity, motivation and satisfaction.

Brain Building

People communicate with words. The brain communicates with chemical and electrical signals. There are trillions of nerve cells – called neurons – throughout the body, but most of these are concentrated in the brain. They link together to form the super motorway of your nervous system. 80% of the brain’s signalling or chat is carried out by just two neurotransmitters (NT) or message-delivering couriers. Glutamate acts as the gas peddle to stimulate activity, and GABA (gamma amino butyric acid) is the brake to relax activity. Too much or too little of either, and you are agitated and hyper-responsive to stress, or depressed and fatigued.

There are also three key neurotransmitters that are in charge of regulating the signalling process. Their primary role is to adjust the flow of information, such as to make more glutamate, or to help a neuron become more efficient or receptive. One of these, serotonin, is the NT officer that keeps activity under control. It affects moods, impulsivity, self-esteem, anger and aggression. SSRI (selective serotonin re-uptake inhibitor) medications such as Prozac target serotonin function to treat depression, anxiety and compulsive disorders.

Dopamine influences attention, physical movement (it is low in shaky Parkinson’s disease sufferers), learning, sense of pleasure and reward (most people with addictions have a high need for its stimulation). The medication Ritalin is given to ADHD children to increase dopamine and assist with focus and calm.

The third key NT – noradrenalin (called norepinephrine in the US) – amps up signals relating to arousal, motivation, attention, and sharpened senses. It activates the sympathetic nervous system which is in charge of the fight-or-flight response (see my TIPS page for …Check Out Your Adrenals).

Brain Food

One more important brain component is a class of protein-based, master molecules called factors. The most prominent is BDNF (brain derived neurotrophic factor), which is produced inside brain neurons, particularly in the hippocampus or learning centre. While NTs are busy couriering their messages, BDNF builds and maintains the mega-motorway cell structure that supports them all. If you sprinkle BDNF on neurons in a Petri dish they will grow new branches.

You can stimulate increased BDNF with mental, physical and social exercise. In both animal and human studies this results in swiftly improved moods and sense of reward, ability to learn, focus and recall. Studies on rats also show that social and emotional deprivation can physically shrink brains, while an environment of enhanced stimuli produces heavier brains with improved neuronal structure that fire signals efficiently.

One of the speediest ways to produce more BDNF in human beings is with physical exercise. It is unleashed when blood is pumping vigorously. When exercise is aerobic and also requires skill – for example, as with tennis or dancing – then the synaptic connections become more complex.

Exercise also triggers the production of more receptors on cells as docking sites for insulin. Insulin is the hormonal courier driver that delivers glucose – your chief fuel for brain and muscle function – to hungry cells. The brain is the first to feel its lack with consequent moodiness, and dulled ability to reason or remember. In time, impaired access to glucose leads to obesity (or hidden visceral fat in thin people), and increased risk for diabetes, cardiovascular disease, and hormone-related cancers.

Reptilian Responses

With stress or anxiety, adrenalin is released first and followed with another adrenal hormone: cortisol. Cortisol is slower acting but more widespread in its actions. It orders the liver to release stored blood sugar and increase its circulating levels in the bloodstream, for fuel to deal with the real or presumed emergency. It blocks some insulin receptors so glucose will only go to prioritised areas for primitive fight-or-flight responses.

The brain is not one of the key recipients. With prolonged stress – which includes social isolation – there is less acuity and more forgetfulness. Fats are also more likely to be stored than burned. High cortisol – also common with depression – kills neurons in the hippocampus so they are less able to branch out and form positive connections. People with depression can stimulate new branches with regular exercise that involves social interaction, or an appealing environment that stimulates the senses.

One of the antidotes to anxiety is high intensity exercise. By copying the state of arousal with increased heart rate and breathing, you can learn that these states do not necessarily mean doom but can instead relate to increased satisfaction. Exercise also increases the calmative NTs tryptophan, serotonin and GABA. Brain scans show that the reasoning and regulating centre of the pre-frontal cortex is smaller in chronically anxious people (and those with attention disorders such as ADHD). Their fear, danger and survival centre – the amygdala – tags too many situations as threatening and keeps flooding the system with cortisol.

A hormone that acts as a brake to hyper-arousal is ANP (atrial natriuretic peptide). It attaches itself to receptors in the hypothalamus and throughout the stress management system to bring calm. Produced by the brain, and by the heart when exercising, it also triples during pregnancy to suffuse the mother and protect the baby’s brain from the toxic effect of stress.

Exercise helps reduce the inflammation associated with most disease, and the apathy linked to low dopamine and ageing. The risk of Alzheimer’s and other dementias – marked by inflammation – reduces by 50% with regular exercise. After a walking programme, MRI scans have shown an improved volume in the pre-frontal cortex among older adults, people with early Parkinson’s disease, and dyslexia. This improved motor ability, mood, memory and concentration. It also enhanced dopamine levels important for a well regulated sense of reward and satisfaction. The reward centre of the brain provides drive and focus through pleasure signals. People with ADHD are unable to direct and maintain attention on demand. They require physically demanding processes for positive reinforcement and biological restructuring. Intense, complex exercise such as martial arts or gymnastics is ideal.

Foods As Drugs

Medications such as Ritalin and some everyday, active agents target reward centres. Caffeine (coffee, black leaf tea, chocolate, soft drinks, ‘energy’ drinks), refined sugar, highly refined carbohydrates that break down rapidly into glucose, and street drugs such as cocaine can excessively stimulate the cluster of dopamine neurons and encourage compulsive consumption. For some people, foods high in MSG, naturally occurring glutamates (especially high in tomatoes), or artificial sweeteners step on the gas peddle of the central nervous system and lead to anxiety, insomnia and a gathering load of seemingly mysterious health problems (see TIPS for Eating with Your Eyes Shut: The Deception of MSG and other Additives). Everyday foods can also alter brain chemistry; see Moods and Foods.

You can be born with or develop an out of control reward system. Addicts of all levels are usually – physically and/or emotionally – isolated individuals. Addiction is defined as when behaviours persist despite negative consequences – can anyone claim no such substance or behavioural relationship? This wires in a memory that triggers reflexive behaviour. These synaptic connections can remain for months or years so it is easy to relapse. New, positive pathways are needed especially to the pre-frontal cortex to better assess risk vs. reward. This area is not fully developed until a person’s mid twenties, so teenagers can be compromised by stimulants and drugs before inhibition centres have fully developed. For everyone, group activities and team sports can structurally remodel the brain with new associations, and increase satisfaction without the self-sabotage of old habits.

Savour your pleasures two times over: in the immediacy of enjoyable physical, mental and social exercise; and in the long term satisfaction of good health, self-respect, and mutually supportive fellowship.

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For further information read SPARK – The Revolutionary New Science of Exercise and the Brain by psychiatrist Dr John Ratey. See also Aging With Grace by David Snowdon, PhD.