Brain scans: IIH, which mainly affects women, has risen six-fold in 15 years, the study shows
A brain pressure disorder that especially affects women, causing severe headaches and sometimes permanent sight loss, has risen six-fold in 15 years, and is linked to obesity and deprivation, a new study by Swansea University researchers has shown.
Rates of emergency hospital admissions in Wales for people with the disorder were also five times higher than for those without.
The condition is called idiopathic intracranial hypertension (IIH). It causes increased pressure in the fluid surrounding in the brain. This can lead to severely disabling headaches as well as vision loss, which can be permanent.
The research team, from Swansea University Medical School, used anonymised health records of Welsh patients held in the SAIL Databank, a national healthcare database managed by the University. They analysed 35 million patient years of data from 2003 to 2017. They identified 1,765 people with IIH during that time, 85% of whom were women.
They recorded the body mass index of people in the sample and estimated their relative deprivation using a standard national scoring system. For each person with IIH, they compared three people with a comparable profile who did not have the condition.
They found:
• A six-fold increase in the number of cases of the disorder over the course of the study – from 12 cases per 100,000 in 2003 to 76 cases in 2017.
• Rates of emergency hospital admissions were 5 times higher in people with IIH, compared to others - 9% of people with IIH require brain surgery to try and preserve vision.
• There were strong links for both men and women between body mass index and risk of the disorder.
• Obesity rates in Wales over the same period rose from 29% of the population to 40%
• For women only, deprivation was linked to risk, even after adjusting for body mass index. Women in the most deprived areas had 1.5 times greater risk of developing the disorder than women in the least deprived areas
Dr Owen Pickrell of Swansea University Medical School, who led the study, said:
“The considerable increase in idiopathic intracranial hypertension we found may be due to many factors but likely mostly due to rising obesity rates. What is more surprising from our research is that women who experience poverty or other socioeconomic disadvantages may also have an increased risk, independent of obesity.”
More research is needed to determine which socioeconomic factors such as diet, pollution, smoking or stress may play a role in increasing a woman’s risk of developing this disorder.
At present we don’t know exactly what causes IIH, but the link with deprivation evident in our research could help provide clues.
Our findings offer yet more reasons why it is essential to address the obesity epidemic, deprivation and inequalities in Wales.”
The study is published in Neurology®, the medical journal of the American Academy of Neurology.