Metabolic and Hormonal Clues Emerge in the Shadow of Functional Neurological Disorder

Functional neurological disorder, a condition in which patients experience very real symptoms such as seizures, weakness and movement problems without structural damage to the nervous system, has long been one of medicine’s most misunderstood diagnoses. Now a new study has turned its attention to a side of the condition that has received surprisingly little scrutiny: the metabolic, endocrine and reproductive health of the people who live with it. The findings suggest that a quarter or more of adults attending a specialist neuropsychiatry service carry diagnoses such as diabetes, thyroid dysfunction or hypertension alongside their neurological symptoms, and they raise an intriguing, if preliminary, question about whether particular subtypes of the disorder carry distinct metabolic fingerprints.

The research, published in Discover Mental Health, was conducted by a team based at City St George’s University, the South West London and St George’s Mental Health NHS Trust, St George’s Hospital and collaborating London institutions. It took the form of a retrospective case record review, meaning the investigators systematically combed through the clinical notes of 282 adults who had received a neurologist-confirmed diagnosis of functional neurological disorder, often abbreviated to FND, while attending a tertiary neuropsychiatry service. Tertiary services sit at the top of the referral pyramid, treating the most complex and treatment-resistant cases, so the cohort represents a heavily clinically burdened population rather than the full spectrum of FND in the community.

The numbers that emerged from the record review were striking. Metabolic disorders appeared in the notes of 25.5 percent of the cohort, while endocrine disorders were recorded in 24.8 percent. Among the individual conditions, diabetes mellitus was the most common, affecting 12.4 percent of patients, followed closely by thyroid dysfunction at 11.7 percent and hypertension at 10.6 percent. For a condition whose clinical presentation is dominated by neurological symptoms, the sheer prevalence of classic cardiometabolic and hormonal disease in this population is a reminder that FND rarely travels alone. Clinicians managing these patients, the authors suggest, are dealing with whole-body health as much as with brain function.

This matters because comorbidity is not a passive backdrop in neurological psychiatry. Conditions such as diabetes and thyroid disease can themselves produce fatigue, cognitive complaints and sensory disturbance, and their presence can complicate diagnosis, prolong referral pathways and shape the rehabilitation strategies that patients are offered. Conversely, living with a disabling functional disorder may influence diet, physical activity and healthcare engagement, all of which feed into metabolic risk. The relationship is almost certainly bidirectional, which is precisely why mapping the landscape of physical comorbidity in FND has become an increasingly urgent task for researchers.

Methodologically, the team went beyond simple prevalence counts. They examined whether particular metabolic and endocrine conditions clustered with particular FND subtypes, using Fisher’s exact tests corrected for the false discovery rate, a statistical adjustment designed to prevent spurious associations from slipping through when many comparisons are made simultaneously. Across this corrected analysis, several nominal associations surfaced between FND subtypes and comorbid conditions, but none survived the correction. That negative result is worth taking seriously: it suggests that the broad categories of metabolic and endocrine disease are distributed fairly evenly across the FND population seen at this service, rather than attaching themselves to specific symptom groups in a way the data could confirm.

One association, however, stood out enough to warrant a second, more careful look. The study examined patients with functional cognitive disorder, or FCD, a subtype of FND characterised by distressing problems with memory and concentration that lack a neurodegenerative explanation. Dyslipidaemia, the abnormal level of blood fats such as cholesterol, was recorded in 29.2 percent of patients with FCD compared with just 7.4 percent of the rest of the cohort. Expressed as an odds ratio, this corresponded to a nearly fivefold unadjusted increase in odds of dyslipidaemia among those with functional cognitive symptoms, with an unadjusted p value of 0.003.

The researchers then applied multivariable logistic regression, adjusting for age and sex, two of the strongest demographic drivers of cholesterol abnormalities. The association attenuated but held: the adjusted odds ratio was 3.75, with a 95 percent confidence interval of 1.29 to 10.90 and a p value of 0.015. In plain terms, even after accounting for who the patients were, the link between functional cognitive disorder and dyslipidaemia remained statistically visible. Yet the authors are careful to label the finding exploratory, because the corresponding unadjusted association did not survive the earlier false discovery rate correction, and the analysis was not designed or powered to test this single hypothesis in isolation.

Why might blood fat abnormalities and functional cognitive symptoms travel together? The authors do not claim a causal mechanism, and the retrospective design forbids any confident inference about direction. It is conceivable that dyslipidaemia contributes to vascular changes that interact with cognitive vulnerability, or that the association reflects shared pathways such as chronic stress, inflammation or lifestyle disruption that influence both lipid metabolism and functional symptom generation. It is equally possible that referral patterns, diagnostic Work-ups, or chance in a modestly sized cohort explain the signal. Larger, prospectively designed controlled studies comparing FND patients with matched controls are the clear next step, and the study’s authors say exactly that in their conclusions.

The study also carries practical implications for the clinic. Roughly one in four patients in the cohort had a recorded metabolic or endocrine condition, which means that a routine neuropsychiatry assessment for FND is, in effect, also an opportunity to screen for diabetes, thyroid dysfunction, hypertension and lipid abnormalities. The authors note that reproductive comorbidities were captured alongside metabolic and endocrine ones, filling a gap they identify in the literature, where such profiles have been underexplored. If clinicians overlook these conditions, patients may find that treatable physical problems are attributed to their functional diagnosis, or vice versa, either of which can delay appropriate care. Integrated models that treat FND within the whole of a patient’s physiology, rather than as a neurological label floating free of the body, are the direction in which the field appears to be moving.

Equally important is what the study does not show. Because every participant had FND and the analysis was largely descriptive and within-cohort, the work cannot establish whether people with FND have more metabolic and endocrine disease than the general population, nor can it determine whether any of these conditions increase the risk of developing FND, worsen its course, or simply coexist with it. The absence of associations surviving multiple-comparison correction counsels against overinterpreting subtype patterns beyond the exploratory FCD signal. Still, by providing a carefully quantified baseline from a tertiary neuropsychiatry cohort, the study gives future investigators a concrete target: prospective cohorts with control groups, standardised metabolic screening and sufficient numbers to test whether the dyslipidaemia and functional cognitive disorder link is real, and if so, what it means for how these patients are investigated and treated.

Subject of Research: Metabolic, endocrine and reproductive comorbidities in adults with functional neurological disorder

Article Title: Metabolic, endocrine and reproductive comorbidities in functional neurological disorder: a retrospective study of a tertiary neuropsychiatry cohort

Article References: Tamilson, B., Telikapalli, N., Poller, A., Nihoyannopoulos, L., Puspuri, K., Tse, J. T. K., Coebergh, J., & Agrawal, N. (2026). Metabolic, endocrine and reproductive comorbidities in functional neurological disorder: a retrospective study of a tertiary neuropsychiatry cohort. Discover Mental Health. https://doi.org/10.1007/s44192-026-00603-4

Image Credits: AI Generated

DOI: 10.1007/s44192-026-00603-4

Keywords: functional neurological disorder, metabolic comorbidity, endocrine disorders, dyslipidaemia, diabetes mellitus, thyroid dysfunction, hypertension, functional cognitive disorder, neuropsychiatry, retrospective study, reproductive health, comorbidity