Differential Diagnosis: Psychopharmacology
Christoff Truter
Spousal caregiver
Interestingly psychopharmacological influences (how drugs affect the mind and behaviour) are known to produce neurological symptoms.
Withdrawal symptoms from psychoactive drugs presenting with neurological features were already recognised in the late 1950s. It was clear even then that stopping these medications disrupted the nervous system (consider the use of antipsychotics, anticonvulsants, opioids, dopaminergic drugs, beta-blockers, lithium, etc, as well).
Those early drugs, such as barbiturates and meprobamate, primarily acted as CNS depressants by enhancing neurotransmitter signalling through GABA-A receptors.
In contrast to older psychoactive drugs, modern antidepressants like SSRIs and SNRIs increase serotonin in the brain’s synapses, altering serotonin regulation to stabilise mood, ease anxiety, and support sleep and appetite. Yet when stopped abruptly, they can trigger neurological symptoms such as dizziness, tremors, and sensory disturbances, formally known as SSRI discontinuation syndrome but sometimes mistaken for FND.
This is unsurprising, as FND is a 100% clinical diagnosis, and its inherently subjective nature can easily lead to such misinterpretations.
What is surprising is that withdrawal of this nature is rarely considered in the differential diagnosis for FND. Just a quick question like: have you recently stopped using antidepressants? (not relevant in our situation, but none of our 4 neurologists, 3 neurosurgeons nor 2 GP's even asked the question).
We also need to consider that gastrointestinal dysfunction can mimic the withdrawal mentioned above as well, since around 90% of serotonin is produced in the gut.
Which raises an intriguing question: could some FND cases actually be serotonin regulation dysfunction?
Recently shared by @recover2renew, Marion Brown (article below) and Stevie Lewis are actively campaigning on prescribed drug dependence and withdrawal, highlighting misdiagnoses of antidepressant issues often attributed to MUS or FND, but by the sounds of it this is not something that is being actively considered at all...
