Is stress shrinking your brain?

Chronic stress affects more than just your mood and energy levels. It affects the size of your brain, the quality of the nerves, the quality of information that is sent via your brain cells (neurons), your brain chemistry but most importantly, the plasticity of your brain.

Your brain is so much more powerful than the computer analogy it is often given. The brain can reprogram itself, fix its own machinery to enable faster connections and work more efficiently. Amazing right? It is called Structural Remodelling.

Under consistent stress, the brain is constantly remodelling and changing gene expression (1).

The core areas affected include:

• The Prefrontal Cortex (PFC) – shrinks under stress

• Hippocampus – shrinks under stress

• Amygdala – first enlarges, then shrinks under stress

The Amygdala

The amygdala’s - you have two, one in each hemisphere. They are a key part of the brains limbic system and it grows larger with stress.

The amygdala is the “emotional centre” in the brain and is responsible for emotions such as fear, aggression, anxiety & motivation. It can also hijack the flight or fight response. When you sense a threat, the amygdala can activate the fight or flight response immediately and cause a surge of hormones through your body including adrenaline (your energy hormone) and cortisol (your stress hormone). This worked for hunters and gatherers to outrun tigers, however today we tend to have more psychological threats such as emails and anxious thoughts.

The consequence of this consistent stress causes remodelling to the amygdala, leading to an increase in both size and strength of the nerves that condition fear. This leads to excessive stress, anxiety, and more feelings of fear.

The Hippocampus

Stress-related structural remodelling is also seen with the hippocampus. The hippocampus is a complex lobe in the brain and changes in this area are seen in mood disorders, such as bipolar, schizophrenia, anxiety and depression. In Major Depressive Disorders, the number of cells there become denser however the actual lobe itself shrinks (2).

When this occurs, it can lead to poor emotional memory recall, inaccessibility of information and memory problems. This can also have a profound effect on dream content and can increase bizarre dreaming. If your dreams are always weird and wacky, maybe its time to check your stress levels!

The Pre-Frontal Cortex

The pre-frontal cortex (PFC) is a vital part of the brain that looks after executive functions, goal-orientated activities, memories, and even the stress response itself. It is the newest part of the brain, the most “evolved”. Under chronic stress, the PFC also shrinks. Nerve cells in this area shrink in response to chronic stress and expand during periods of recovery (3).

If you suffer from chronic stress, and your nervous system is constantly activated by TV, mobile phone use, social media use, gaming, working late or insomnia, chances are there is little recovery time. This is required for the cells to expand back to normal size. Changes in the PFC can influence your cognitive function, emotions, self-regulation, hormones and mood (4).

Remodel your brain with meditation

Meditation is one of the best tools we have available to structurally remodel the brain. Meditation has been shown to remodel the brain after just 8 weeks of daily practise (5). In this clinical trial, daily mindfulness practises, lasting 20 minutes, combined with 12 hours of face-to-face meditation classes was enough to see structural changes on a brain MRI. Brain scans done on regular meditators also shows a different brain structure, including smaller amygdala volume (6).

For those who don’t have time, remember 20 minutes is only 1.4% of your day!

For more ideas on how to protect your brain, check out my blog post - six tips to support your brain health.

References:

1. McEwen, B. S., Bowles, N. P., Gray, J. D., Hill, M. N., Hunter, R. G., Karatsoreos, I. N., & Nasca, C. (2015). Mechanisms of stress in the brain. Nature neuroscience, 18(10), 1353–1363. https://doi.org/10.1038/nn.4086

2. Stockmeier, C. A., Mahajan, G. J., Konick, L. C., Overholser, J. C., Jurjus, G. J., Meltzer, H. Y., Uylings, H. B., Friedman, L., & Rajkowska, G. (2004). Cellular changes in the postmortem hippocampus in major depression. Biological psychiatry, 56(9), 640–650. https://doi.org/10.1016/j.biopsych.2004.08.022

3. McEwen, B. S., & Morrison, J. H. (2013). The brain on stress: vulnerability and plasticity of the prefrontal cortex over the life course. Neuron, 79(1), 16–29. https://doi.org/10.1016/j.neuron.2013.06.028

4. Arnsten A. F. (2009). Stress signalling pathways that impair prefrontal cortex structure and function. Nature reviews. Neuroscience, 10(6), 410–422. https://doi.org/10.1038/nrn2648

5. Hölzel, B. K., Carmody, J., Evans, K. C., Hoge, E. A., Dusek, J. A., Morgan, L., Pitman, R. K., & Lazar, S. W. (2010). Stress reduction correlates with structural changes in the amygdala. Social cognitive and affective neuroscience, 5(1), 11–17. https://doi.org/10.1093/scan/nsp034

6. Gotink, R. A., Vernooij, M. W., Ikram, M. A., Niessen, W. J., Krestin, G. P., Hofman, A., Tiemeier, H., & Hunink, M. (2018). Meditation and yoga practice are associated with smaller right amygdala volume: the Rotterdam study. Brain imaging and behavior, 12(6), 1631–1639. https://doi.org/10.1007/s11682-018-9826-z