To celebrate International Day of Happiness, and the importance the natural world has in promoting and achieving happiness, we are sharing a guest blog and deep dive into the links between bugs, brains, green spaces and mental well-being from Mark Millan, a neuroscientist specialising in the study and improved treatment of disorders of brain.
Although there is still plenty of progress to be made, the urgency of conjointly combatting the intertwined issues of climate change and biodiversity loss is increasingly recognized. The need to protect both symbolic species like pandas and tigers, as well as the less iconic invertebrates upon which ecosystems depend, is likewise now better accepted. This is important since invertebrates, as exemplified by insects, fulfil multiple roles in ecosystems. For example, they provide an indispensable food resource for frogs, hedgehogs, bats and a plethora of birds inhabiting meadows, marshes and woods – as well as parks and gardens; likewise potential refuges of biodiversity – if cared for with nature in mind. The crucial significance of bees in the pollination of essential food crops has now entered the public consciousness, a role shared with wasps, flies and moths, and one that extends to non-agricultural plants as well.
A somewhat less familiar facet of gardens and other “green spaces” (vegetation-flower-shrub-tree-rich areas, rather than cropped lawns) – together with their interdependent vertebrate and invertebrate habitants – is their positive influence upon mental well-being (Howarth et al, 2020; Douglas and Douglas, 2021; Song et al, 2022). A disengagement from nature, and being brought up in a bleak, urban environment, increases the risk of poor mental health. Conversely, greater exposure to green spaces helps blunt stress and promote mental well-being, with favourable observations seen from adolescents to the elderly. This research is particularly interesting in light of the Covid pandemic. People fortunate enough to have access to green spaces, whether private or public, spent more time in them. This enhanced their connection with nature, and probably helped to compensate for the reduction in social interactions, reducing the risk of a deterioration of mental health due to social isolation. Several uncertainties remain to be clarified. Which features of green spaces most beneficially influence mood, and exactly how does the brain respond? What is the relationship between time spent in green spaces and physical exercise as regards the influence upon well-being? How does exposure to green spaces interact with other variables like pollution and socio-economic status? Despite these open questions, the overall benefit of exposure to nature and green spaces for mental health is widely accepted (Coventry et al, 2021; Nejade et al, 2022), so efforts are being made to establish guidelines for urban environments. For example, respecting a 3-30-300 maxim whereby everybody should ideally be able to see at least 3 trees from their home, live in a neighbourhood possessing at least 30 percent tree cover, and reside less than 300 m away from the nearest green space (Konijnendijk, 2022). This is clearly not the casetoday!
As mentioned above, insects are core components of terrestrial ecosystems and crucial for maintaining the integrity, diversity and richness of the green spaces that contribute to mental and physical well-being. The inherent attractiveness of species like butterflies, bees and beetles adds to their appeal and to their positive impact upon mood. Furthermore, getting involved in the conservation of green spaces and bugs encourages a positive mind-set, and is a rewarding and socially-integrated activity that should further promote well-being and brain health. Contact with green spaces (together with their fauna and flora) can, then, moderate the impact of stress and reduce the risk of anxiety and depressed mood. To add an important caveat, spending time in nature does not represent a panacea for serious neuropsychiatric/neurological disorders – where professional aid and appropriate therapy is strongly advised – but it may, like optimized nutrition, enhance the efficacy of conventional treatments.
Intriguingly, links between bugs and brains, and between ecosystems and mental health, lie even deeper. The brain is a highly complex network comprised of an interacting and diverse assembly of units: molecules, organelles and cells, neurotransmitters, neurons and neural circuits, and structures like the cortex, hippocampus and the cerebellum, the whole brain itself being embedded in a web of social partners (Sporn, 2010; Bertolino and Bassett, 2019; Krendl and Bretzel, 2022). This parallels the hierarchical organization of ecosystems, comprised of distinct “trophic” levels and numerous classes of interacting species, with bugs interlinking the various tiers in several ways: for example, in releasing nutrients to soil, being both consumers and a food source themselves, and acting as pollinators (see above). Complex networks with high levels of “degeneracy” (redundancy) are generally quite resilient since one species of animal (in an ecosystem) or class of neuron (in the brain) can compensate for a functionally similar one should there be damage or loss. Networks are nonetheless vulnerable to multiple and sustained stressors that disrupt links, provoking the transition to a pathological state. For example, deregulation of specific genes in the brain, in collusion with early life trauma/infection, can lead to neurodevelopmental disorders. Further, the accumulation of neurotoxic proteins in the aging brain, together with a shortfall in metabolic energy, can harm neurons and trigger Alzheimer’s disease. As for ecosystems, pesticides add to habitat loss in provoking their fragmentation and dysfunction, in particular when pollinating insects are eradicated. In the marine world, loss of coral reef polyps (invertebrates related to sea anemones) due to climate change/sea-warming and over-fishing similarly prompts their collapse.
For both mental health and conservation, the old adage that “prevention is better than cure” rings very true since – like Humpty Dumpty (putting him back together again) or unbaking a cake – it’s not easy to reverse harm once it has happened! Nonetheless, it is worth highlighting some exceptions. For example, in several disorders of infants, the faulty gene that damages the brain can be corrected or replaced, while there has been progress in restituting ecosystems like coral reefs, wetlands and forests, and in re-introducing species like bison, wolves and endangered butterflies into their traditional habitats. Restoration can, then, be feasible under certain conditions, even if the primary goal is to be preventative: here, so-called “biomarkers” that provide advance warning of imminent harm to brains or ecosystems can help avert the worst.
In essence, we are inherently a part of – and dependent upon – a range of planetary ecosystems, which we need to better protect for our mutual benefit. There is still the time and opportunity to achieve this goal, insects and other invertebrates being pivotal to global conservations efforts, but it is essential to devote the requisite resources! We can also connect ourselves more closely to nature, with positive effects both for our overall health and for our mental well-being 🙂 !
Mark John Millan was born in Edinburgh. He originally studied Natural Sciences (Zoology and Ecology) at Cambridge but retrained thereafter in Neurosciences at the Max Planck Institute for Psychiatry in Munich, and he has continued his research into the causes, prevention and treatment of disorders of the brain in France where he has worked for more than 30 years. He has published more than 400 papers, been cited more than 30,000 times, and won several prizes. He frequently evokes ecosystems in his lectures since their damage and the resulting loss of biodiversity, together with climate change, have a negative impact on mental – and physical – health.
Millan is also a keen photographer, exhibiting his work at various collective and solo exhibitions. Converging his professional and personal interests, he has photographically documented invertebrate life in his partially re-wilded garden just outside Paris as a basis for articles, talks and exhibitions that encourage people to do more to preserve biodiversity locally – as well as globally – with benefits for their own mental well-being as well as for nature itself.