Surging nervous system disorders now top cause of illness — study

PARIS, France — Conditions affecting the nervous system — such as strokes, migraines and dementia — have surged past heart disease to become the leading cause of ill health worldwide, a major new analysis said.

More than 3.4 billion people — 43 percent of the global population — experienced a neurological condition in 2021, far more than had previously been thought, the analysis found.

The study was carried out by hundreds of researchers led by the US-based Institute for Health Metrics and Evaluation (IHME), which has become a global reference for health statistics.

Lead study author Jaimie Steinmetz of the IHME said the results showed that nervous system conditions are now "the world's leading cause of overall disease burden."

Cases of these conditions have soared by 59 percent in the last three decades, she said, with the increase mainly driven by the fact that the world's population was ageing and growing fast.

The researchers looked at how 37 different neurological conditions affected ill health, disability and premature death across 204 countries and territories from 1990 to 2021.

This data was used to estimate how many years of healthy life were lost to each condition, called disability-adjusted life years (DALYs).

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More than 443 million years of healthy life were lost to nervous system disorders globally in 2021, an 18-percent increase from 1990, the study found.

However, if the population's age and growing size was adjusted for, DALYs and deaths from these conditions actually fell by around a third, the researchers said.

Stroke, which was previously counted as a heart disease, was by far the worst neurological condition analyzed, accounting for 160 million years of healthy life lost.

It was followed by a form of brain damage called neonatal encephalopathy, migraine, dementia including Alzheimer's disease, nerve damage from diabetes, meningitis and epilepsy. Cognitive impairment from COVID-19 ranked 20th.

The main reason that nervous system conditions surpassed cardiovascular disease in the latest analysis was a recent World Health Organization classification change that moved stroke into the