Brain health does not have an evidence problem. The science arrived years ago, and it is not subtle. In 2021, conditions affecting the nervous system reached an estimated 3.4 billion people, about 43 percent of everyone alive. They overtook cardiovascular disease as the leading cause of illness and disability in the world. The single largest source of lost healthy years now sits inside the human skull. What brain health has is a joining-up problem.

The knowledge is vast. What gets done with it is piecemeal.

Instead of one effort, the field is carved into territories. Alzheimer’s here, mental health there, stroke and epilepsy each with their own specialists and their own charities, each drawing on a separate stream of research funding, rarely meeting across the lines that divide them. The brain is treated as a collection of distinct diseases rather than one organ under many kinds of pressure.

One Brain, Many Silos

Why does the largest health burden in the world still get tackled in pieces? Part of the answer is structural. Each field is competent on its own terms. Each also competes for research funding, policy attention, and a share of a health budget that is never big enough.

And the splintering runs counter to the shape of the problem. The conditions that get studied separately share risk factors and underlying biology. The same Lancet Neurology analysis links air pollution to stroke risk and lead exposure to a large share of the global burden of intellectual disability.

The people best placed to act do not think in therapeutic areas at all. A finance ministry thinks in terms of productivity and dependency ratios. An education system thinks in cognitive development. An employer thinks in workforce capacity. Approach each of them through a single disease, and they see a fragment. Show them the whole, and the case becomes theirs.

The Climate Is a Brain Health Problem Too

The adjacencies are where the fragmentation becomes expensive. Take climate. A 2024 review led by Professor Sanjay Sisodiya at UCL found that higher temperatures and sharper swings in temperature raise hospital admissions for dementia, worsen seizure control in epilepsy, aggravate multiple sclerosis, and increase both the incidence of stroke and the deaths that follow it. 

During the 2003 European heatwave, around a fifth of the excess deaths were among people with neurological conditions. Sisodiya did not hedge: there is, he said, “clear evidence for an impact of the climate on some brain conditions”. The mechanisms are not all settled, and correlation and causation remain tangled in places. But climate is, among other things, a brain health problem. It is rarely treated as one.

Take the arts. The largest evidence review to date, a 2019 WHO scoping review drawing on more than 900 publications, found a real role for the arts in preventing ill health and in managing conditions from dementia to depression. Art therapy belongs in the picture of brain health. It reaches the same organ from a direction that clinical medicine rarely looks in.

This is the big-tent moment the field keeps failing to seize.

Climate, education, the arts, sport, the workplace: each shapes the brain, and each sits in a different silo of research, funding and policy. The dots are all on the page. Nobody is joining them.

What Joining the Dots Would Take

So what would joining them actually require? Start with the economics, because that is what moves ministries. The McKinsey Health Institute estimates the brain capital opportunity at up to $11.7 trillion in global economic value, and the OECD and the Brain Capital Alliance go further, treating brain health and brain skills as economic infrastructure alongside physical and financial capital rather than beneath it. Seen that way, brain health becomes an economic priority, and economic priorities are the ones that reach the treasury.

The policy world has already conceded the point. When all 194 WHO member states adopted the Intersectoral Global Action Plan on epilepsy and other neurological disorders in 2022, the operative word in the title was intersectoral, meaning a response coordinated across sectors rather than passed back and forth like a baton. 

The mandate exists. What is missing is delivery built the same way: research that crosses the lines between diseases, prevention that reaches into the places that shape the brain, from air quality to classrooms to workplaces, and care that treats mental and neurological health as neighbours rather than strangers. None of this is easy. The incentives still reward the silo, and the specialist who owns one corner of the brain is rarely rewarded for looking at the rest.

Science has already stopped drawing hard lines between these things. It treats the brain as one organ, shaped by climate and pollution and education and art, worn down and built back along the same paths. The way the brain is researched, funded, and cared for has not kept pace. Whether it is finally addressed as one problem rather than many is a question the next decade will have to answer.