Neuropsychiatry is a mature discipline, with origins that can be traced to the mid-nineteenth century or perhaps as early as the seventeenth century,1 long before the birth of modern psychiatry. For many decades, however, its growth was stunted as the fields of neurology and psychiatry devoured the landscape and carved out their respective territories. In its reemergence in the last two decades, neuropsychiatry’s first impulse, almost by default, was to redefine itself in relation to neurology and psychiatry. Unfortunately, it has been forced to place itself in the border-zone—a no-man’s land—a territory equally claimed or shunned by the two disciplines.2 This domain is forever changing, depending on the fortunes of the combatants on either side, creating an untenable position for neuropsychiatry. Twenty-first century commentators are calling for an integration of neurology, psychiatry, and the neurosciences,3 providing a new backdrop for the debate on the future of neuropsychiatry. It is in this context that many question whether there will be a need for neuropsychiatry, and if so, whether there will be a future for neurology and psychiatry as distinct disciplines. This editorial seeks to explore the key issues pertaining to the differentiation of these specialties and suggests a way forward for neuropsychiatry.
The advance of neuroscience is inexorable, and its footprint on psychiatry is ever increasing. Psychiatry has generally accepted the promise of neuroscience and has altered its practice whenever new developments have demanded that the field modify itself. It has even attempted to influence psychotherapy and psychoanalytic concepts such as dreaming with neuroscientific concepts.4 This embedding of neuroscience into psychiatry is the kind of rapprochement with neurology for which many commentators have recently argued.5,6 It makes neuroscience the grindstone on which the blades of both psychiatry and neurology are sharpened. However, neuroscientific progress is unlikely to unite the two disciplines into one super discipline of neuropsychiatry.
In the foreseeable future, psychiatry and neurology will continue as two distinct disciplines, with different skills and pathways of training, but the cross-talk will undoubtedly increase, and the frameworks will converge and create a need for greater cooperation. Despite their commonalities, psychiatry and neurology are distinct clinical disciplines that require separate expertise and have vastly different demands placed upon them. The strengths of psychiatry lie in the rich description of mental phenomena, well-developed interviewing skills, understanding of multiple causation of behavioral disturbance, appreciation of individual variation, ability to deal with ambiguity, interpersonal context, and the combination of biological with psychological and behavioral therapies. Equally, neurology prides itself in its rigorous clinical examination skills, its empiricism, and its objectivity. The training experiences necessary for both disciplines are separate, and an amalgamation runs the risk of diluting both.
Neurologists often demonstrate an anxious avoidance of psychiatric patients, and psychiatric practice is usually difficult to combine with rigorous physical examination and investigation. The rapid increase in scientific knowledge will continue to challenge clinicians’ ability to maintain the skill and knowledge basis of their discipline, such that a neurologist, no matter how well-trained, will find it impossible to acquire sufficient psychiatric skills to achieve competence in this field and vice versa. Even, for example, if a genetic basis for schizophrenia is discovered and a "cure" found, psychiatric skills would still be necessary to manage the patients in the context of their family and social environment. Understanding psychotic phenomena, developing the skills to interview psychotic patients, establishing a rapport with them and dealing with treatment compliance are skills acquired by years of psychiatric training, which is unlikely to change despite scientific advance. For instance, the development of effective antidepressant drugs has not reduced the need for specialized psychiatric training in the diagnosis of affective disorders or the skillful use of the large number of antidepressants currently available. A contemporary example from neuropsychiatry is Alzheimer disease. Rapid advances have occurred in the last 15 years, yet much of the tertiary management of this disorder in many countries is in the domain of neuropsychiatry and psychogeriatrics rather than neurology, which will more than likely continue. A rapprochement does not entail an amalgamation. Psychiatry and neurology can therefore rest assured that their respective futures as individual disciplines are secure.
Should neuropsychiatry claim its own territory to have its own future? If so, how should this be delineated? Here, one can distinguish between neuropsychiatric "territory" and the neuropsychiatric "approach," although the need for the latter influences the former. As an example, the management of Tourette syndrome requires familiarity with movement disorders as well as obsessive-compulsive disorder, attention deficit disorder, conduct disorder, mood disorders, specific developmental disabilities, and sleep disorder and requires skills in pharmacotherapy, behavior therapy, family therapy, genetic counseling, and rehabilitation. A skilled neuropsychiatrist is capable of managing such a case far better than a combination of clinicians from different disciplines. The neuropsychiatrist brings the basic skills of psychiatry and neurology together and combines them with expertise in neuroimaging, neuropsychology and neurophysiology to bear upon the condition, thereby demonstrating the neuropsychiatric approach. This would appear to be the essence of neuropsychiatry. By its application, however, some disorders can be identified that are best dealt with using the neuropsychiatric approach, thereby delineating the "territory" of the discipline.
Is the neuropsychiatric approach sufficient to secure the discipline, or is a claim to a territory comprising certain disorders essential? There are disciplines within medicine that have a basis in sharing a particular approach, for example, radiology or nuclear medicine. These disciplines specialize in a particular set of techniques for diagnosis across all medical conditions and do not lay claim to the diagnosis and management of any definite set of disorders. In my opinion, this is unlikely to provide a secure basis for a discipline of neuropsychiatry. What characterizes neuropsychiatry is the skill of its proponents in a variety of methods and techniques rather than a monopoly over any one particular technique. As the skill base shifts and developments in neuroscience redefine the landscape of diagnostic methods, the neuropsychiatric approach will change and evolve and will constantly need to reinvent itself. A more secure basis can be found in certain disease entities and disorders than can be justifiably labeled as neuropsychiatric, that is, by fencing in a neuropsychiatric territory.
There are many disorders that currently fit the bill of being "neuropsychiatric." What characterizes them is that the principles of either psychiatry or neurology are unable to fully encapsulate these disorders, and the neuropsychiatric approach is needed for their diagnosis and management. The diagnoses that come to mind are neurocognitive disorders; drug-induced movement disorders; Tourette syndrome; psychiatric disorders associated with other movement disorders such as Parkinson’s disease and dystonia; psychiatric disorders associated with epilepsy; cerebrovascular disease and head injury; chronic fatigue syndrome and other psychoneuroimmunological disorders; attention deficit hyperactivity disorder; and other conditions in which cognitive, behavioral, or affective disturbance results directly from brain insult. The cognitive disorders, which include the dementias, are a large group that currently falls into the territory of old-age psychiatry and geriatric medicine for specialized care, with the primary care physician retaining a major role. While these remain a legitimate interest of neuropsychiatry, the assessment and management of young onset dementia are currently neglected aspects of dementia that fall distinctly within the purview of neuropsychiatry. It is a field that neuropsychiatry can easily claim and develop to make a major contribution to the welfare of this relatively neglected group. The neurodevelopmental disorders, which include various syndromes associated with intellectual handicap, are neuropsychiatric disorders that warrant a pediatric subdivision. Moreover, upon graduating into adulthood, young patients are left without a specific division for treatment. Neuropsychiatry could fill this void, however. Together, these disorders comprise a body of clinical work that can underpin a robust discipline. Some neuropsychiatrists place territorial claims on schizophrenia and bipolar disorder, citing the studies supporting their biological basis. In my opinion, this is an erroneous inference, as the mere fact of a "biological" etiology does not place a disorder outside the domain of psychiatry.
The "biologization" of psychiatry is inevitable, and the mind-brain dichotomy is increasingly under threat. In this climate, the promise of neuropsychiatry should involve special skills, without which particular clinical disorders cannot be managed. Schizophrenia is unlikely to be one of them, although some aspects of schizophrenia such as drug-induced movement disorders, secondary schizophrenia or particular physical treatments (e.g., transcranial magnetic stimulation [TMS] for auditory hallucinations) will fall within the neuropsychiatric territory. The same can be said for bipolar disorder. Neuropsychiatry cannot afford to be expansive on the back of a neuroscientific juggernaut, as psychiatry and neurology have tickets for the same ride.
Territorial claims are dynamic processes that are resolved by historical developments and shifts in thinking. Chronic fatigue syndrome, said to be a neuropsychiatric disorder by some, is currently treated by general physicians, psychiatrists, neuropsychiatrists and immunologists. Since many neuropsychiatric disorders occur in the elderly, neuropsychiatry has considerable overlap with psychogeriatrics. Similarly, because neuropsychiatric disorders are commonly seen in the medical and neurological wards, liaison psychiatry and psychosomatics specialists are called upon to see them. This overlap notwithstanding, neuropsychiatry has special areas of strength that will help determine boundaries with psychogeriatrics and psychosomatic medicine. The latter disciplines have a broader range of coverage than the disorders mentioned previously, thereby diluting their expertise in neuropsychiatric disorders. For example, psychogeriatricians are trained to recognize and treat behavioral and psychiatric syndromes of dementia but not to investigate dementia associated with neurological disease or early onset dementia. Liaison psychiatrists are comfortable with dissociative disorders, but not with episodic dyscontrol or epileptic psychosis. The discipline of psychogeriatrics is defined by the age of its clients rather than any approach to management or a theoretical underpinning. Psychogeriatrics, therefore, should collaborate with neuropsychiatry in a tertiary role in order to complement the field in certain cases.
While pharmacotherapy will remain the central modality of treatment of the above disorders, there is major interest in the development of new physical treatments in psychiatry.7 Expertise in pharmacotherapy is likely to continue to reside securely within biological psychiatry, as there is strength in numbers, but neuropsychiatry should be free to draw on this resource. In addition, there is a promise of new physical treatments that neuropsychiatry is well positioned to lay claim to. For many decades, psychiatric neurosurgery formed a major component of neuropsychiatric practice in Australia, the United States, the United Kingdom, and some European countries. With its decline, there are novel treatments promising to supplant it. Transcranial magnetic stimulation has already established itself as an experimental tool par excellence and has made inroads into clinical practice as a neuropsychiatric treatment.8 Vagus nerve stimulation (VNS) shows early promise as a treatment for depression,9 and deep brain stimulation (DBS) is now being investigated in psychiatric disorders, particularly obsessive-compulsive disorder.10 In the future, other psychiatric treatments such as gene therapy, stem cell use, and brain implants are likely to involve direct brain intervention and may be regarded as neuropsychiatric in nature. Future neuropsychiatrists will, therefore, be well served if they develop expertise in the existing and future techniques that are of potential use as treatments for psychiatric disorders. As a corollary, neuropsychological counseling and cognitive rehabilitation are nonbiological treatment modalities that neuropsychiatry should embrace. This field has yet to blossom, but it is self-evident that the current rehabilitative and counseling services will be inadequate if and when it does.
The neuropsychiatric investigation of patients relies on new technologies in neuroimaging and neurophysiology. For example, rapid advances in magnetic resonance imaging (MRI) have taken it beyond the simple investigation of brain morphology. Diffusion weighted imaging (DWI) is currently being used to investigate the integrity of the blood-brain barrier,11 and diffusion tensor imaging (DTI) is being used to investigate white matter tracts in vivo.12 Magnetic resonance imaging can be used to measure brain perfusion using exogenous contrast tracking or arterial spin labeling.13 Magnetic resonance spectroscopy (MRS) is able to perform a limited chemical "biopsy" of the living brain.14 Functional MRI (fMRI) has become the preeminent technique to investigate brain function while the brain is actively engaged.15 Positron emission and single photon emission tomography are now well-established techniques used to investigate brain metabolism, blood flow, and neurochemistry.16 Neurophysiology offers excellent techniques to map the electrical activity of the brain, and such techniques can be combined with structural and functional imaging to offer a multimodal perspective of the brain.17 These new approaches are mainly research-oriented, but their clinical applications are emerging, and their widespread application is imminent. As these approaches become more complex, special knowledge will be necessary for their optimal use, and neuropsychiatry must place itself in pivotal position to exploit these and other developments as they occur.
In the process of defining its terrain, neuropsychiatry will inevitably spawn subspecialties. It may seem unwise to go so far as to discuss possible subspecialties when neuropsychiatry itself is just beginning to shed its adolescence of identity formation. However, this may be the best approach to attract and retain some neuropsychiatrists into the fold. The field of developmental disability or mental retardation deals with a range of disorders that warrant the diagnostic and treatment input of neuropsychiatry. Since the focus of intervention occurs during the time when patients are young, a pediatric neuropsychiatry is likely to emerge. This subspecialty will also have a keen interest in attentional disorders, epilepsy and Tourette syndrome. Cognitive neuropsychiatry has grown to become a specialized field, which is a "systematic and theoretically driven approach to explain clinical psychopathologies in terms of deficits to normal cognitive mechanisms,"18 thereby linking cognitive neuropsychology to clinical psychiatry. While cognitive neuropsychiatry remains a theoretical discipline, the multiple brain-behavior models it suggests may open avenues to future treatment research. One example is the application of TMS to treat auditory hallucinations, which benefits from cognitive neuropsychiatric models of hallucinations.19
The intent to claim clinical territory goes with a responsibility to provide high-quality services. Models for such services will need to be developed regionally, but the intent is to make neuropsychiatry a tertiary-level service with established referral patterns from psychiatry, neurology, geriatrics, and general medicine. The nature of the expertise required makes it necessary for the core services for neuropsychiatric diagnosis and assessment developed in academic centers to have access to high quality neuroimaging and neurophysiology and support from other specialties. Since many neuropsychiatric patients need medium- and long-term hospitalization for cognitive therapy or rehabilitation, the assessment services will need the support of medium- and long-term beds with appropriate models of care. Practical models for such services are urgently needed, and these will vary in detail from region to region, depending on local imperatives.
The future of a profession is secured by the quality of training of its newest members, and therefore neuropsychiatry must develop a training agenda. Training requirements have regional disparities, but a core curriculum would have wide application. Ideally, the International Neuropsychiatric Association should develop such a curriculum, but organizations such as the American Neuropsychiatric Association, with their vast intellectual resources, could take the initiative. Important decisions must be made in relation to the composition of the training deemed necessary. For example, what proportion of psychiatric, neurological, and specialist neuropsychiatric training should constitute the overall training? What levels of skills are needed in neuroimaging and clinical neurophysiology? How much neuropsychological expertise is required? What emphasis should there be on research as a component of training? Most of the current generation of neuropsychiatrists around the world is self-trained, but this situation cannot lead to a secure professional status for the future.
Finally, neuropsychiatry must develop its research agenda. An agreement on its territory will suggest a pathway for research, but the nature of the discipline makes it necessary that research be multidisciplinary and not constrained by narrow conceptualizations. Neuropsychiatry is a frontier discipline rooted in neuroscience, and it must use all the tools of neuroscience currently available in order to advance its knowledge base in both the etiology of disorders and their effective management. Collaboration with the disciplines of psychiatry and neurology is both inevitable and desirable. This should not be seen as threatening, since the future of neuropsychiatry cannot afford to be isolationist. It must then also establish collaborations with neuropsychology, genetics, psychopharmacology, diagnostic radiology, immunology, neurophysiology, rehabilitation, and many other disciplines. In this endeavor, neuropsychiatry must look beyond the traditional reaches of psychiatry and neurology.
"Forward, ho!" is the short answer to the question, "Whither neuropsychiatry?" However, as history has shown, this can sometimes result in a cyclical movement. To secure a future, current practitioners of neuropsychiatry, especially its leaders, must take the appropriate steps to develop the identity of the discipline, making it meaningful to its clientele and future professionals. In other words, the future is now, and the ensuing debate should be robust and vigorous but also culminate quickly in necessary action.