'Nature is heavy' – how climate change affects the brain

Soaring rates of anxiety, depression, ADHD, PTSD, Alzheimer's and motor neurone disease may be related to rising temperatures and other environmental changes, according to a new book.

The climate crisis has spurred "visceral and tangible transformations in our very brains", wrote Clayton Page Aldern, author of "The Weight of Nature", in The Guardian. As the planet "undergoes dramatic environmental shifts", so too does our "neurological landscape".

'Nature is heavy'

"Fossil-fuel-induced changes" are affecting our brains, "influencing everything from memory and executive function to language, the formation of identity, and even the structure of the brain", wrote Aldern. "The weight of nature is heavy," he said, "and it presses inward."

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For example, blue-green algae, which is blooming more often due to climate change, releases a potent neurotoxin that offers "one of the most compelling causal explanations" for the incidence of motor neurone disease, according to Burcin Ikiz, a neuroscientist at the Baszucki Group, a mental health philanthropy organisation.

Aldern also explained that after Superstorm Sandy hit New York in 2012, researchers studied the children of women who were pregnant during the incident. They found that they bear an "inordinately high risk" of psychiatric conditions today because of pre-natal stress.

Boys had 60-fold and 20-fold increased risks of ADHD and conduct disorder, respectively, while girls experienced a 20-fold increase in anxiety and a 30-fold increase in depression compared with girls who were not exposed. They described their findings as "extremely alarming".

Environmental changes due to climate change could lead to alterations in brain development and function, concluded a report by the University of Vienna last year. The researchers were "particularly concerned about the effects of extreme weather events and pollution on cognitive abilities and mental health", said Neuroscience News.

There is also "emerging evidence of associations between poor air quality, both indoors and outdoors, and poor mental health more generally, as well as specific mental disorders", said a study in the British Journal of Psychiatry. It concluded that pollution causes increased cases of depression, anxiety and psychosis.

'In its infancy'

Recognising the connection is not entirely new. Since the 1940s, scientists have known from mouse studies that "changing environmental factors" can "profoundly change the development and plasticity of the brain", said Neuroscience News, and many of the connections between climate and mental health "feel intuitive", said Aldern.

For instance, he pointed out that "when the weather gets a bit muggier, your thinking does the same", and that hotter days can cause "feelings of aggression".

But anxiety about environmental connections creates another bridge. A survey by the British Association for Counselling and Psychotherapy found that almost three-quarters (73%) of 16- to 24-year-olds reported that the climate crisis was having a negative effect on their mental health.

Our mental health is "so intrinsically tied to everything around us that we constantly see on the news", one youngster told The Guardian last year, adding that they take antidepressants.

Understanding the relationship between mental health and climate remains relatively shallow, said The Guardian, because "as a cohesive effort, the field – which we might call climatological neuroepidemiology – is in its infancy".

Therefore, said the University of Vienna researchers, an intersection of neuroscience and environmental studies would help us "better understand and address these impacts".