Clinical vignette

A 51-year-old woman with a background of temporal lobe epilepsy, for which she sees a neurologist on a yearly basis, is referred to a community psychiatrist from primary care. She presents with depressive symptoms and subjective memory impairment. A diagnosis of a moderate depressive episode is made. In addition to the standard biopsychosocial approach to affective disorders, the psychiatric profile of her current anti-epileptic medication (lamotrigine) and the possible effects of antidepressant medication on her seizure threshold are discussed. Her symptoms partially respond to the introduction of a selective serotonin reuptake inhibitor (sertraline) and supportive psychotherapy. Her psychiatrist has the following questions:

• Are any specialist services available for patients with psychiatric disorders associated with neurological disease?

• What information should a referral to behavioural neurology/neuropsychiatry contain?

What is behavioural neurology/neuropsychiatry?

The Cartesian mind–body duality is enshrined in medicine by the distinction between organic and functional disorders. Classically, neurology has been concerned with the investigation, diagnosis and management of brain disorders with demonstrable physical signs and cerebral pathology. Psychiatry, on the other hand, has focused primarily on the diagnosis and management of disturbed behaviour, impaired cognition and abnormal affect. Psychiatric disorders were thought to be ‘functional’ or psychological in origin, i.e. not associated with demonstrable neuropathology. The rise of the depth psychologies introduced by Freud and Jung led to the view that psychological and social processes are the key drivers of mental disturbance. The dominance of the psychosocial approach is still evident in the configuration of mental health services (Reference Bullmore, Fletcher and JonesBullmore 2009).

However, over the history of British medicine the separation of neurology and psychiatry has not always been so stark. John Hughlings Jackson (1835–1911), a key figure in the development of British neurology and psychiatry (Reference Janković, Sokić and LevićJanković 1997), described the psychomotor phenomena associated with temporal lobe epilepsies and proposed the ‘dissolution’ theory, which would later inform Freud's structural topography of the psyche and the positive–negative dichotomy in schizophrenia. On the European continent, the German neurologist and psychiatrist Wilhelm Griesinger (1817–1868) famously stated that ‘mental diseases are brain diseases’ (Reference GriesingerGriesinger 1845). The introduction of antipsychotics (neuroleptics) in the 1950s lent weight to the suggestion that mental diseases are not dissimilar to brain diseases. Then a seminal paper in the mid-1970s demonstrating anatomical differences between the brains of patients with schizophrenia and unaffected controls definitively showed that the psychiatric disturbances of schizophrenia are associated with brain abnormalities (Reference Johnstone, Crow and FrithJohnstone 1976).

Over the intervening 40 years significant progress has been made, with an increasing understanding of the genetic and biochemical basis of mental illness. This has led to the development of a specific approach within psychiatry called ‘biological psychiatry’ (Reference David, Fleminger and KopelmanDavid 2012). The subspecialties of behavioural neurology and neuropsychiatry have emerged (Reference Arzy and DanzigerArzy 2014). Both seek to bridge the ideological gap between neurology and psychiatry and are concerned with understanding disorders of behaviour, affect or cognition in terms of cerebral dysfunction.

The ‘cerebral dysfunction’ described here is not necessarily structural or localised in classic terms. Psychiatric phenomena have been shown to be associated with neurochemical disturbances and impaired connectivity between widely dispersed brain networks. For example, dysfunction in the salience network, which enables switching between different brain states, has been implicated in the formation of psychotic symptoms (Reference Palaniyappan, White and LiddlePalaniyappan 2012).

Behavioural neurologists and neuropsychiatrists have special expertise in the diagnosis and management of psychiatric disorders occurring in the context of neurological disease. Teasing apart the aetiological mechanisms of mental illness in patients with neurological comorbidity can be challenging, as both biological factors related to the underlying neurological disorder and psychosocial stressors interact to inform the expression of psychiatric comorbidity.

Who are behavioural neurologists and neuropsychiatrists?

Behavioural neurologists are physicians who complete core medical training, higher specialist training in neurology and then develop a special interest in the behavioural manifestations of brain pathology. There is no specific training pathway, but interested trainees are encouraged to gain additional clinical experience in established clinics and to engage in subject-specific audits or research. Behavioural neurologists have an important role in considering the relative contributions of organic and psychiatric morbidity and how they interact.

Neuropsychiatrists complete core psychiatric training, higher specialist training in general psychiatry and then develop a special interest in the brain mechanisms underlying psychiatric symptoms. Additional experience in specialist clinics and postgraduate courses such as the MSc in Clinical Neuropsychiatry hosted by the University of Birmingham can complement clinical experience. Neuropsychiatrists, through their psychiatric training, have additional experience of various psychotherapeutic approaches, including cognitive–behavioural therapy and psychodynamic psychotherapy. They also have clinical expertise in the use of the mental health legislation.

In June 2014 the Royal College of Psychiatrists set up the Faculty of Neuropsychiatry. The Faculty expands previous work by the Section of Neuropsychiatry and brings together a number of special interest groups (including the brain injury, epilepsy, sleep, complex neurodisability and movement disorder working groups). It aims to promote neuropsychiatry, develop a curriculum and training pathway, foster research and influence service development.

Behavioural neurologists and neuropsychiatrists work in a number of settings, including National Health Service (NHS) mental health partnership trusts, and they offer an important tertiary-level service. Both specialties are mainly out-patient-based, although in-patient facilities, with multi disciplinary teams, are available in specialist centres in Northampton, Birmingham, North Benfleet (Essex) and Mansfield (Nottinghamshire). These are run by St Andrew's Healthcare, a charity that provides NHS services (www.standrewshealthcare.co.uk). Behavioural neurologists and neuropsychiatrists may also be involved in the medical assessment of patients within the criminal justice system.

What do behavioural neurologists and neuropsychiatrists treat?

Broadly speaking, behavioural neurologists and neuropsychiatrists are involved in the management of behavioural problems complicating neurological disease that present diagnostic and therapeutic challenges. They are also involved in the multidisciplinary management of patients with ‘complex neurodisability’. These are patients who present with multiple neurodevelopmental disorders characterised by motor and behavioural problems. They are usually seen in intellectual disability or child and adolescent mental health services (CAMHS). Behavioural neurologists and neuropsychiatrists are also involved in the assessment and care of patients with functional neurological disorders, including psychogenic seizures and psychogenic movement disorders.

Table 1 summarises the psychiatric comorbidity associated with common neurological conditions. Neuropsychiatric disorders are also associated with more pervasive changes in personality. For example, Geschwind syndrome is a personality syndrome characterised by circumstantiality, altered sexuality and intensified mental life. It is classically described in temporal lobe epilepsy, but may also occur in other epilepsy syndromes (Reference Devinsky and NajjarDevinsky 1999).

TABLE 1 Psychiatric disorders associated with common neurological conditions

There is currently no comprehensive epidemiological population-based study of the incidence or prevalence of neuropsychiatric comorbidity across all neurological disorders. However, a number of cross-sectional studies across Europe have estimated the prevalence of psychiatric disorders in neurology out-patients at approximately 50%, with anxiety and depression being the most commonly reported conditions (Reference Carson, Ringbauer and StoneCarson 2000; Reference Fink, Hansen and S⊘ndergaardFink 2003). The identification and treatment of psychiatric comorbidity is important to decrease impairment in health-related quality of life, prevent caregiver distress and reduce health and social care costs (Reference Aarsland, Larsen and KarlsenAarsland 1999).

Issues arising from the general adult psychiatry and behavioural neurology/neuropsychiatry interface

MCQs

Select the single best option for each question stem

1. 1 Which of the following statements is false?

   1. a Depression is common in patients with epilepsy

   2. b Huntington's disease is associated with choreiform movements

   3. c Traumatic brain injury is often associated with depression and anxiety

   4. d Alzheimer's disease never requires input from a behavioural neurologist/neuropsychiatrist

   5. e Tic disorders are associated with behavioural problems in the vast majority of cases.

2. 2 Which of the following statements is false?

   1. a Behavioural neurologists/neuropsychiatrists can work in both out-patient and in-patient settings

   2. b Psychiatric phenomena are not associated with disturbed neural networks

   3. c Behavioural neurologists/neuropsychiatrists are currently based in specialist centres throughout the UK

   4. d The cost per patient per year is different for general adult and behavioural neurology/neuropsychiatry services

   5. e Behavioural neurologists/neuropsychiatrists are often involved in forensic consultations.

3. 3 Which of the following statements is true?

   1. a Behavioural neurologists initially train as psychiatrists

   2. b Neuropsychiatrists initially train as physicians

   3. c Behavioural neurologists/neuropsychiatrists do not have access to multidisciplinary teams

   4. d Behavioural neurology/neuropsychiatry is a secondary service

   5. e There are psychometric rating scales for assessing depressive symptoms in epilepsy.

4. 4 An appropriate primary reason for referral to behavioural neurology/neuropsychiatry is that:

   1. a the patient poses a suicide risk

   2. b the patient has depression and develops episodes of cataplexy and sleep paralysis

   3. c the patient has an IQ below 70

   4. d the patient has a history of epilepsy and substance misuse

   5. e the patient has a history of childhood epilepsy which has completely resolved.

5. 5 Which of the following is not likely to help resolve disagreements at the interface between general adult psychiatry and behavioural neurology/neuropsychiatry?

   1. a A protocol for the management of patients across services

   2. b No explicit referral criteria

   3. c Regular liaison among colleagues

   4. d An audit of referrals to behavioural neurology/neuropsychiatry

   5. e Serious case reviews.

MCQ answers

1

d

2

b

3

e

4

b

5

b