- Overview of functional neurological disorder
- Prevalence of psychiatric comorbidities in FND
- Common psychiatric conditions associated with FND
- Diagnostic challenges and clinical implications
- Treatment approaches and integrated care strategies
Functional neurological disorder (FND) is a complex condition characterised by the presence of neurological symptoms—such as weakness, tremors, seizures, or sensory disturbances—that are not explained by identifiable structural or pathophysiological abnormalities in the nervous system. Although historically known by terms such as “conversion disorder” or “hysteria,” contemporary understanding emphasises the genuine distress and disability experienced by individuals with FND, distinguishing it from malingering or factitious disorders.
FND occupies an intersection between neurology and psychiatry, making it a unique and often misunderstood diagnosis. While the symptoms mimic those of neurological diseases such as epilepsy, multiple sclerosis, or Parkinson’s disease, they do not conform to conventional patterns of neurological deficits. Instead, they are thought to arise from a functional disruption in brain networks, particularly those involved in motor control, attention, emotion regulation, and sense of agency.
This disruption may be influenced by a combination of psychological, biological, and social factors. One of the most important associations observed in FND is comorbidity with psychiatric conditions, such as depression and anxiety. These comorbidities are not present in all individuals with FND, but they are common and often play a role in symptom presentation and persistence. The interrelationship between FND and psychiatric disorders underscores the biopsychosocial nature of the condition, requiring a multidisciplinary approach to evaluation and management.
Diagnosis of FND relies on identifying positive clinical features rather than merely excluding other neurological conditions. For example, variability or inconsistency in symptoms, such as leg weakness that disappears when distracted, are regarded as positive signs. Advances in neuroimaging and cognitive neuroscience have begun to elucidate some neural mechanisms underlying FND, offering hope for improved diagnostic clarity and therapeutic options in future.
Prevalence of psychiatric comorbidities in FND
The comorbidity of psychiatric disorders with functional neurological disorder (FND) is prevalent and has been consistently observed across clinical and epidemiological studies. Various investigations have suggested that up to two-thirds of individuals diagnosed with FND also meet diagnostic criteria for at least one psychiatric condition. Anxiety and depression constitute the most frequently documented psychiatric comorbidities, often preceding, coinciding with or following the onset of neurological symptoms. These co-existing conditions not only complicate the clinical picture but may also influence the development, severity and chronicity of FND symptoms.
Population-based studies and clinical cohorts confirm that psychiatric comorbidities are more common in patients with FND than in the general population. A number of large-scale cohort studies have reported rates of depression in FND patients as high as 60%, while anxiety disorders—including generalised anxiety disorder, panic disorder and post-traumatic stress disorder—appear in approximately 40–50% of cases. Personality disorders and somatic symptom disorders are also disproportionately represented in FND populations, suggesting a complex interplay of psychological vulnerabilities and neurological symptom expression.
Although the high prevalence of psychiatric comorbidity should not be interpreted as implying that FND is exclusively psychiatric in origin, it does highlight significant overlap, both in phenomenology and in the underlying neurobiological substrates. For instance, neuroimaging studies have demonstrated abnormalities in brain regions related to affective processing and emotional regulation in those with FND, mirroring findings in individuals with mood and anxiety disorders. These shared neural mechanisms may contribute to the close association between emotional dysregulation and functional symptoms.
It is important to note that not all individuals with FND have a co-occurring psychiatric diagnosis, and the absence of such comorbidity does not rule out the condition. Nevertheless, recognising the high prevalence of psychiatric disorders in this population is crucial for formulating a comprehensive and individualised care plan. Early identification and management of depression, anxiety, or other psychiatric conditions in the context of FND can significantly affect prognosis, response to treatment and quality of life. The co-existence of these disorders necessitates a biopsychosocial framework for understanding the patient’s experience and tailoring effective interventions.
Common psychiatric conditions associated with FND
Several psychiatric conditions are commonly associated with functional neurological disorder (FND), reflecting a complex and dynamic interplay between psychological and neurological factors. Among the most frequently observed comorbidities are mood disorders, particularly major depressive disorder and generalised anxiety disorder. These conditions often precede or emerge alongside the onset of functional neurological symptoms, and their presence can complicate both the clinical presentation and the course of FND.
Depression is frequently documented in individuals with FND, with many patients reporting symptoms such as persistent low mood, anhedonia, fatigue and cognitive impairments. The relationship between depression and FND is likely bidirectional: depressive symptoms can exacerbate neurological complaints, and living with unpredictable and disabling functional symptoms can in turn contribute to a deterioration in mood and quality of life. Neurobiological research indicates overlapping dysfunctions in brain regions involved in emotional processing and somatosensory integration, including the amygdala, insula and prefrontal cortex.
Anxiety disorders are also commonly present, with panic disorder, social anxiety, and post-traumatic stress disorder (PTSD) noted in numerous clinical cohorts. Panic attacks may trigger or amplify functional symptoms such as non-epileptic seizures, while hypervigilance and heightened arousal associated with PTSD can maintain or worsen motor and sensory symptoms. The central role of anxiety in shaping the experience of physical symptoms reveals the importance of targeting this comorbidity therapeutically.
Additionally, somatic symptom disorder and health anxiety are prevalent among patients with FND. These conditions involve heightened concern and preoccupation with physical symptoms, alongside maladaptive behaviours such as excessive health-seeking or avoidance. These behaviours may lead to reinforcement of functional symptoms through attentional focus, safety behaviours and altered sensory perception. The overlap of these conditions with FND presents a diagnostic challenge, requiring careful assessment to identify the primary disability while acknowledging the psychological context.
Personality disorders—particularly those within the borderline and avoidant spectrums—have also been identified in individuals with FND, though to a lesser degree than mood and anxiety disorders. Features such as emotional instability, interpersonal difficulties and identity disturbance may influence illness behaviour, adherence to treatments and the therapeutic alliance. These traits, when present, underscore the need for long-term, collaborative psychosocial intervention strategies.
In light of the commonly observed comorbidity between FND and psychiatric disorders, particularly depression and anxiety, clinicians must adopt an integrative approach to assessment and treatment. Understanding the influence of these conditions on symptom development, maintenance, and recovery is essential to providing effective and compassionate care to individuals affected by this multifaceted disorder.
Diagnostic challenges and clinical implications
Diagnosing functional neurological disorder (FND) presents clinicians with a range of challenges, many of which stem from the condition’s overlap with psychiatric comorbidities and its atypical presentation within standard neurological frameworks. Unlike most neurological disorders that are defined by objective biomarkers or structural lesions, FND is characterised by functional impairments without detectable neurological damage, making it essential to depend on positive clinical signs for diagnosis. These include features such as inconsistency of symptoms, distractibility, or entrainment in tremors, but such signs may be missed or misinterpreted in routine practice.
The presence of comorbid psychiatric conditions, such as depression and anxiety, introduces additional complexity to the diagnostic process. These psychiatric disorders can obscure or mimic neurological symptoms, potentially leading to misdiagnosis or a delay in appropriate treatment. For example, panic attacks and dissociative episodes may resemble epileptic seizures, while severe depressive psychomotor retardation might be mistaken for a movement disorder. Moreover, when psychiatric comorbidity is identified, it can inadvertently contribute to diagnostic overshadowing, where clinicians may attribute all symptoms to a psychological origin, thereby overlooking the functional neurological nature of the condition.
Patients often undergo extensive investigations, including neuroimaging and electrophysiological tests, to rule out other neurological conditions. While this is sometimes necessary, excessive reliance on exclusionary diagnostics can reinforce patients’ fears of serious illness or give rise to frustration when no structural explanation is found. The lack of clear communication regarding the diagnosis of FND can further exacerbate this frustration, contributing to scepticism about the legitimacy of the condition among patients and even healthcare professionals.
Clinically, the diagnostic process demands a sensitive and patient-centred approach. It is critical to convey the diagnosis to individuals in a manner that validates their symptoms as real and distressing, while also explaining the functional nature of the disorder. This not only strengthens the therapeutic alliance but is also associated with better treatment outcomes. Clear explanation of FND, emphasising that symptoms are due to dysfunction rather than damage, can provide relief to patients and reduce stigma often associated with psychiatric-based interpretations.
The implications of diagnostic challenges in FND extend beyond individual misdiagnoses and affect healthcare systems at large. Misunderstanding or delayed diagnosis can result in unnecessary procedures, failed treatment trials, recurrent hospital visits, and increased healthcare costs. Moreover, if psychiatric comorbidities such as depression and anxiety are not appropriately assessed and managed, there is a heightened risk of chronicity and functional impairment. Clinicians must therefore be vigilant in adopting a dual-track approach that addresses both neurological and psychological domains of health in tandem.
Education and training of healthcare professionals are essential to improve recognition of FND and its associated psychiatric diagnoses. Improved diagnostic confidence can decrease the stigma surrounding the condition and promote the use of standardised, evidence-based approaches in both general and specialist settings. Incorporating mental health expertise into neurology teams, as part of a biopsychosocial model, can further facilitate timely recognition and intervention for the diverse manifestations of FND and its comorbidities.
Treatment approaches and integrated care strategies
Treatment of functional neurological disorder (FND) requires a multifaceted, patient-centred approach that fully recognises the frequent comorbidity with psychiatric conditions such as depression and anxiety. Management strategies must therefore address both the functional neurological symptoms and the psychological aspects that often accompany them. The implementation of integrated care strategies has proven beneficial in achieving better outcomes, enhancing symptom control, and improving patients’ overall quality of life.
Cognitive behavioural therapy (CBT) is among the most extensively studied psychological treatments for FND. It has demonstrated efficacy in reducing symptom severity, improving emotional regulation, and decreasing functional disability. CBT interventions often focus on identifying and challenging unhelpful beliefs about symptoms, reducing symptom-focused attention, and enhancing coping mechanisms. For individuals with comorbid depression or anxiety, CBT can be adapted to target both the functional symptoms and the specific psychiatric conditions concurrently, making it a crucial component of comprehensive care.
Physiotherapy tailored to FND is another cornerstone of treatment, particularly for individuals with motor symptoms such as weakness, tremor or gait disturbances. A specialist physiotherapist trained in recognising and responding to the unique features of FND can guide rehabilitation through gradual re-engagement in normal movements, distraction techniques, and functional task training. When physiotherapy is incorporated within a multidisciplinary framework that includes mental health support, outcomes are significantly improved, especially in patients where psychological comorbidity such as anxiety contributes to physical manifestations.
Pharmacological interventions should primarily address psychiatric comorbidities rather than the core functional symptoms of FND, as there is limited evidence supporting medication specifically for FND itself. Selective serotonin reuptake inhibitors (SSRIs) and other antidepressants may be prescribed for comorbid depression or generalised anxiety disorder, helping to stabilise mood and reduce anticipatory anxiety that may worsen or trigger functional symptoms. It is important, however, that any pharmacological treatment be carefully titrated and integrated with psychological and physical therapies, avoiding the overmedicalisation of symptoms in isolation.
Multidisciplinary care is widely acknowledged as the gold standard for managing FND. Teams often include neurologists, psychiatrists, psychologists, physiotherapists, occupational therapists, and social workers, working collaboratively to address the diverse aspects of a patient’s condition. This integration allows for consistent communication, coordinated treatment planning, and efficient monitoring of progress. Such a model is especially important in cases with complex psychiatric comorbidity, where interventions need to be dynamically adjusted based on evolving needs and symptom responses.
Psychoeducation is another vital element of treatment. When delivered effectively, education about the diagnosis—framed within a biopsychosocial model—can help reduce stigma, build trust, and empower patients to actively engage in therapy. Explaining the role of stress, emotional conflict, or trauma in symptom development does not negate the legitimacy of the physical symptoms but instead provides a constructive framework for recovery. Patients who understand that functional symptoms are reversible disruption rather than damage are more likely to adhere to therapeutic strategies and regain function.
In recent years, specialist FND clinics have emerged in several regions to provide structured, multidisciplinary treatment pathways. These centres often serve as hubs for clinical expertise, research, and education, offering advanced assessment and long-term management options for individuals with persistent or severe FND. Access to such services can be life-changing for patients, particularly those with enduring symptoms and high levels of psychiatric comorbidity.
Ultimately, the successful treatment of FND hinges on recognising the individuality of each patient’s experience. Addressing symptoms in isolation without considering the broader psychosocial context—including comorbid depression and anxiety—risks incomplete treatment and suboptimal outcomes. An integrated strategy that combines medical, psychological, physical, and educational interventions offers the most promising route to sustained recovery and improved wellbeing.
