In people with a functional neurological disorder (FND), the brain generally appears structurally normal on clinical MRI scans but functions incorrectly (akin to a computer software crashing), resulting in patients experiencing symptoms including limb weakness, tremor, gait abnormalities, and non-epileptic seizures.
In some cases, childhood maltreatment may have been a risk factor, yet links between risk factors such as childhood abuse and the development of FND remain poorly understood.
In a new study, researchers examined the brains of individuals who experienced early-life trauma, some with FND and others without the condition.
The findings may provide a better understanding of what happens in the brains of some patients with FND, as well as those with various other trauma-related brain disorders.
The research was led by a team at Massachusetts General Hospital (MGH).
In the study, the team examined 30 adults with FND and 21 people with depression. Some of the participants in both groups had experienced early-life maltreatment, as determined through questionnaires.
In FND patients only, differences in the severity of childhood physical abuse were linked to differences in connections between certain regions of the brain.
For example, between the limbic regions which control emotions, arousal and survival instincts among other functions, and the primary motor cortex which is involved in voluntary movements.
In additional assessments, the team examined how the expression of genes related to brain areas showing prominent plastic effects correlated to the degree of early-life physical abuse in patients with FND.
As background, some genes in the literature have been shown to increase the risk for developing brain disorders after experiencing early-life maltreatment.
The researchers found that brain areas showing prominent functional reorganization in patients with FND were the same brain areas highly expressing genes involved in neuroplasticity and nervous system development.
The team says childhood maltreatment may be a risk factor for the development of FND in some people, but there are many social, environmental, and biological factors that likely influence the development of FND later in life.
More work is needed to understand how the brain mechanisms underlying FND in those without prominent childhood maltreatment.
The lead author of the study is Ibai Diez, Ph.D., a senior research fellow in Neurology and Radiology at MGH.
The study is published in Molecular Psychiatry.
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