As shared in a press release by the American Academy of Neurology; the medical community had taken note of the rare brain pressure disorder idiopathic intracranial hypertension (IIH) when they noticed a sharp increase in both new cases and hospitalizations. The rare brain pressure disorder, known for its debilitating headaches and vision loss, was known to be associated with both obesity and deprivation.

At Swansea University Medical School in Wales, a team of researchers wanted to find out who these patients were and what was responsible for the trend.

In a analysis of over 35 million people spanning 15 years, doctors learned that the disorder had risen six-fold throughout the decade and a half. They also found a link between females’ socioeconomic status and propensity for becoming sick with the primarily-female disease while controlled for obesity; though interestingly doctors note, the disease was not correlated with socioeconomic status for males.

Idiopathic intracranial hypertension is a rare condition caused by pressure built up inside the skull without a clear underlying cause. The majority of those diagnosed are females between ages 20 and 35.

Though not a brain tumor, the condition causes similar symptoms—including moderate to severe headaches behind the eyes, ringing in the ears  in sync with the heartbeat, nausea, vomiting, dizziness, blurred vision, episodes of blindness, double vision, trouble with peripheral vision, seeing flashes of light, and neck, shoulder, and back pain.

While the specific cause of the condition is unknown, researchers believe obesity plays a significant role, as well a a resistance to the flow of cerebrospinal fluid.  Patients are recommended to  pursue a healthier weight if necessary, by way of surgery. There are also medicines to relieve the brain pressure and alleviate symptoms. They also have their eyes monitored for vision loss.

Doctors wanted to measure the surge in cases and gather evidence on what is causing so many to be effected by unwieldy headaches and impaired vision. The Welsh team analyzed anonymized health records of 35 million patients gathered from a national healthcare database, spanning from 2003 to 2017. They found 1,765 people with IIH, each of whom they compared to three controls with similar demographic information but without the rare condition. 85% of the cases found were female.

They searched for data to analyze the hypothesis that obesity and socioeconomic status play a role in the development of the disease. The researchers considered each person’s body mass index, a measure of the body’s fatness, and created a score estimating each person’s relative deprivation using the UK’s standard scoring system, which creates a score to bottle up a person’s socioeconomic circumstances.

Over the course of 15 years, they found a staggering six-fold increase in cases of IIH. That is, what had effected 12 patients per 100,000 people in 2003 effected 76 patients per 100,000 by the time the study concluded. They also found a strong correlation between a high BMI and the disorder for both sexes. They point out that notably, Wales saw an increase in rates of obesity over the same period, rising from about 29% to 40% of the country.

Interestingly, though they found a correlation between deprivation and IIH, it only applied to females.  Even once adjusted for BMI, they found that the majority of the females were grouped into the lowest two of the five socioeconomic groupings. This meant that even once adjusted for weight, females considered ‘deprived’ were 1.5x more likely to develop the disease than those not deprived.

 Since the disorder is much more common in females, it was of note that their SES was also more impactful on their health outcome. Pickrell explained, “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.”

The disease can be enormously cumbersome, causing not only frequent sickness but more severe eye and vision issues. They found those with IIH visited the emergency room on average five times as often as the general population. Of them, 9% needed brain surgery which attempted to remedy their failing vision.

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While the sample’s large sample and time frame provides a clear picture of rising rates, with links to overall trends towards weight gain; more research is needed to dig deeper into these contributing factors. While researchers considered the person’s relative deprivation, this was based on their region rather than their specific economic information. In order to draw out the specific factors causing the uptake in this  disease, more research would be needed to dive into the components of deprivation.  Nevertheless, these insights are already important.

While medical professionals do not know exactly what causes IIH, they believe that their research will provide clues. This research also demonstrates the need to address deprivation, the obesity epidemic, and inequality in Wales.