Three studies suggest there is a potential link between the chronic, autoimmune condition lupus – in which the patient’s immune system attacks the body’s own healthy cells – with dementia, the umbrella term for a variety of cognitive disorders affecting memory and learning (e.g. Alzheimer’s disease which accounts for 60% to 80% of dementia seen around the world).

It is estimated that at least five million people worldwide suffer from lupus. It affects women more than men; and most people afflicted with the condition are between the ages of 15 and 44. Out of the four different types, the most common form is systemic lupus erythematosus – also known as SLE – accounting for approximately 70% of all lupus cases. It can cause damage to the joints, kidneys, lungs, skin, blood vessels and brain, which may in turn lead to conditions such as kidney failure, arthritis and seizures.

All three studies are a result of Big Data

The first study was published in in April 2016 in the Arthritis Care and Research journal, and was conducted by researchers from the Taipei Medical Hospital. Using the Taiwan Longitudinal Health Insurance Database 2005, which is a record of the 99.9% of Taiwanese citizens that are covered by the country’s national health insurance, lead author Dr Yu-Ru Lin and his colleagues took a random sampling and compared the dementia rates in patients with SLE with those without, matching for age and sex.

The researchers found that the risk of dementia doubled in SLE patients. There were 357 cases per 10,000 people in each age group in the lupus cohort, compared to 180 cases per 100,000 people in the same age group in the non-SLE cohort.

The second study was published in March 2017, in the Journal of Epidemiology and Community Health by researchers from the University of Oxford in the UK. Led by Michael Goldacre, a professor of public health, at the university – information from 1.8 million individuals who were admitted to hospital with an autoimmune disease between 1998 and 2012, in the UK, was reviewed.

When compared with patients admitted for other reasons, those with an autoimmune disorder were 20% more likely to be readmitted at a later date for dementia. More specifically, patients with lupus had a 46% increased risk of developing dementia when compared with non-autoimmune disorder patients. in addition, the risk of vascular dementia for patients of autoimmune disorders in general was 28% higher.

Recent study found that there is an increase in dementia among people with SLE.
Recent study found that there is an increase in dementia among people with SLE.

The final study was published in November 2017, in the International Journal of Geriatric Psychiatry – where it matched 4,886 people with SLE by age and sex with 24,430 individuals, who did not have the condition, and measured the incidence of dementia. They discovered a 51% increased likelihood across every age group.

The study, which was co-authored by Daniela Amital of the Sackler Faculty of Medicine at the Tel Aviv University in Israel, was conducted by analysing information from the Clalit Health Care Database, which housed the data of more than 4.4 million individuals in Israel.

What might cause such correlation?

While it is still unknown the exact cause for this potential link, Lin suggested in his paper that it may be antiphospholipid antibodies (found in lupus patients), putting patients at risk of micro-stroke – or it could be anatomical changes in the brain, or alternatively, corticosteroid treatments, which are commonly used for lupus treatments, could contribute to cognitive decline.

Dr Yehuda Shoenfeld, an autoimmunity researcher also from Tel Aviv University says, “When you have organic damage to the brain, being autoimmune in nature, it causes chronic damage to the brain and eventually, there is some kind expression that above this threshold it can cause the psychological defects which are expressed as dementia. It's like accumulating damage.”

It is therefore important for medical practitioners to remember that there is a difference between neurological symptoms of SLE and dementia. Neurological symptoms of SLE are usually tested for using X-rays in which you can see defects in neurological functions such as nerve performance.

As Shoenfeld notes, neurological symptoms “can be represented by conversions. It can be represented by paralysis. It can be presented as paraesthesia, which means it feels like ants are going on your body. So it's more in the domain of physical examination. Dementia is more that you lose your capacity for cognition, memory or so forth. You cannot detect it by X-rays, but you can detect it by talking to the patient and listening to him and you can see that he's not finding himself, I would say, in space. So this is a big difference.” MIMS

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