Research has long indicated that depression and epilepsy are bidirectionally associated. This has been confirmed by data from Denmark’s comprehensive health registries. The bidirectional association is so strong that a diagnosis of depression or epilepsy increases the risk of getting the other diagnosis for up to 20 years.
When a person develops epilepsy, the thoughts about having such a serious disease could probably affect the person’s mood so much that they develop depression.
Epilepsy does not just increase the risk of being diagnosed with depression. The relationship is also bidirectional, meaning that developing depression increases the risk of later being diagnosed with epilepsy.
The research results confirm a very strong association between these two conditions that may be related to the biology of the brain.
“This indicates a fundamental association that may be based on the brain’s neurotransmitters and imbalances in the brain’s circuits. These conditions have several common denominators that are also relevant for treatment individually and collectively,” explains a researcher behind the study, Eva Bølling-Ladegaard, PhD Fellow, Department of Clinical Medicine, Aarhus University.
The research has been published in Neurology.
Data from nearly 9 million people
To better elucidate the bidirectional association between epilepsy and depression, Eva Bølling-Ladegaard used data from Denmark’s health registries.
The researchers used data on 8,741,955 people: 139,014 had been diagnosed with epilepsy and 219,990 had been diagnosed with depression at some point in their lives.
The median age at diagnosis for both conditions was 43 years.
The researchers followed these people for several decades to determine whether a diagnosis of epilepsy increased the risk of also being diagnosed with depression later in life compared with a broad cross-section of the population without epilepsy. And vice versa.
Clear association between epilepsy and depression
The results show that being diagnosed with epilepsy increased the risk of later being diagnosed with depression by 88%.
Conversely, being diagnosed with depression was associated with a 135% increased risk of later being diagnosed with epilepsy.
The risk of being diagnosed with depression after a diagnosis of epilepsy and vice versa was highest in the years immediately following the time of the epilepsy diagnosis but continued to be elevated for up to 20 years.
Finally, the researchers also found that being diagnosed with depression after a diagnosis of epilepsy was associated with a 20% higher risk of emergency admissions from epileptic seizures.
”Our results confirm the indisputable bidirectional relationship between the two conditions and also indicate aspects that others may have overlooked: for example, that there is an increased risk of seizures requiring hospitalisation and that the association is strong even if decades have elapsed between the times of the two diagnoses,” says Eva Bølling-Ladegaard.
Greater focus on the link between the two conditions
According to Eva Bølling-Ladegaard, the study suggests that there should be greater focus on the bidirectional relationship between epilepsy and depression. This applies both in clinical practice and in the drug treatment of the two conditions.
She says that increasing the level of screening for depression among people with epilepsy and increased awareness in the other direction would be sensible.
”Especially people with epilepsy should be screened because depression can increase suicidal thoughts and early death. This can also increase the risk of becoming treatment-resistant to anti-seizure drugs, without us knowing why,” explains Eva Bølling-Ladegaard.
In addition, she indicates that the results show that healthcare professionals should be aware of not only the risk of the double diagnosis immediately in the first years after the first diagnosis but also the risk in the long term.
“This applies regardless of whether you have monitored people for 6 months or 15 years. More research also needs to be carried out on the underlying mechanisms of the bidirectional relationship between the two conditions. Traditionally, research and treatment related to epilepsy and depression have been separated, but we need to recognise and address a very large grey area,” concludes Eva Bølling-Ladegaard.