The Psychosis Prodrome.
Psychotic disorders are devastating for individuals and their families as they involve the onset of symptoms and significant impairment during adolescence and young adulthood- two critical developmental periods when youth are only just starting to make a transition into independence. These disorders are highly prevalent (impacting between 1-2% of the population), and once diagnosed, involve a chronic course and challenging prognosis. However, an emerging research field suggests that we can now effectively identify those who are at imminently high-risk for psychosis, several years before onset (Figure 1).
High-risk syndromes are defined, in part, by attenuated positive symptoms (e.g., experiencing unusual thoughts, seeing brief shadows, hearing strange sounds). Individuals with these syndromes also show persistent difficulties with motor, perceptual, cognitive and emotive functioning. Cumulative, changes during the high-risk (or prodromal period) result in significant impact in social, academic and occupational functioning. Those who meet criteria for a high-risk syndrome have a chance of developing schizophrenia or an affective disorder with psychotic features within a two-year period. This serves as a foundation for a line of research that suggests that if we can identify high-risk adolescents and young adults and provide early intervention, the course of illness will be improved or perhaps prevented entirely.
How Can We Conceptualize the Prodrome?
In a neural diathesis-stress conceptualization of psychosis, individuals with a biological susceptibility (i.e., from inherited genes, mutations, and early prenatal teratogen/insult) often exhibit subtle signs of impairment from infancy and then carry these signs forward throughout childhood (e.g., delayed achievement of milestones such as walking/talking/toilet training; motor abnormalities; poor social skills and affective responsivity; cognitive deficits).
Much later, these vulnerabilities interact with the substantial environmental stressors and dramatic neural and endocrine maturational factors that occur during adolescence and early young-adulthood. During this time normative age related increases in sex hormones synergistically affect neurotransmitters and modulate gene expression. Further marked neural reorganization affects both connectivity and intercommunication between key brain structures and networks. It is also important to consider that the adolescent and young-adult time periods are characterized by a significant number of major life-stage decisions, as well as increases in every day stressors and responsibilities. Each of these social requirements involves making adult decisions without the benefit of a fully developed adult brain (e.g., limiting impulsive thinking and promoting efficient thinking). This can place additional burden on a progressively compromised system (indeed, one common experience is feeling more "thrown-off" by every day stressors). Finally, individuals in these stages are often exposed to additional environmental stresssors including substance abuse. Together, the early vulnerability interacts with adolescent and young-adult developmental factors as well as social and environmental stressors, contributing to emerging subtle attenuated psychotic symptoms. Some common symptoms include: finding a greater degree of meaning in everyday coincidences (aberrant salience), seeing shadows out of the corner of one’s eye, mild grandiosity, feeling vaguely suspicious of friends and family and experiencing increasing difficulty in getting one’s point across. In addition to these symptoms, adolescents and young adults in the prodrome often report negative symptoms (e.g., feeling low motivation, not enjoying things that were previously held to be pleasurable, feeling emotionally disconnected from the self or others), as well as difficulties with cognition (this can present as difficulty concentrating and increasing difficulty in school or at work) and emotional processing (this can present as exhibiting increasing difficult with processing and interacting with social situations). In turn, these emerging symptoms lead to increased stress, which may tax progressively compromised neural and hormonal systems. Indeed, because stressors influence hormones, and because of the important role that hormones (including stress hormones) play in regulating genes responsible for guiding brain development, the noted difficulties and environmental stressors can impair neural development, and consequently, contribute to further vulnerability. This may drive a cascade which eventually drives the onset of formal psychosis (e.g., schizophrenia, bipolar disorder with psychotic features, depression with psychotic features).
Why Does Development Matter?
Although serious mental illness can occur during a number of developmental periods, a majority of cases first develop at the end of adolescence and beginning of young-adulthood. As a result, it has become increasingly clear that developmental factors play an important pathogenic role. As seen in Figure 3, significant brain reorganization during adolescence and young adulthood overlaps with the emergence of symptoms. At the same time, the hormone system is highly active, regulating puberty by governing genes that modulate synaptic pruning and white-matter development. Both developmental systems are highly sensitive to environmental and social factors as well. Because of the emphasis on development in understanding factors in the high-risk period, we also focus each of our research questions within this context. With this in mind, the lab is dedicated to longitudinal research, and we employee a range of experimental paradigms and methodologies to assess the same individuals at different developmental time points. We are particularly interested in how factors contribute to an early vulnerability, and then, how environmental factors occurring during adolescence and young adulthood as well as brain and hormone development in this period unmasks this vulnerability, leading to emerging symptoms and other characteristics that impair quality of life and contribute to disability in these individuals.
What are the Priorities for Research in this Area?
The available research has consistently shown that roughly 10-35% of adolescents and young adults exhibiting a prodromal or high-risk syndrome (i.e., based on the course, frequency, and severity of a combination of the symptoms and characteristics noted above) will convert to a psychotic disorder within a two-year period (Figure 4).
A growing body of evidence also suggests that early intervention may be helpful for those at risk for psychopathology. Specifically, forming relationships with treatment providers prior to serious illness, adopting strategies prior to when severe and acute symptoms can interfere with the acquisition and assimilation of psychotherapy skills (e.g., stress management), engaging family members in both reducing the stressful environment and helping to monitor the subtle changing symptoms, and/or beginning treatment can ameliorate course of illness, and may help to delay or even prevent onset of a psychotic disorder.
Unfortunately, although we know that approximately 1/3rd of high-risk individuals will convert to an Axis I psychotic disorder in a short period of time, we are not certain whom among the at-risk group is most likely to fall into this category. As blanket treatment for all high-risk individuals is not a feasible method for intervention (due to costs of psycho-social and pharmacological interventions as well as ethical concerns relating to medication side-effects), identifying those individuals at highest risk for this conversion is a urgent and important research priority. Further, developing new effective targeted treatments (capable of treating symptoms and characteristics that are impairing, but have yet benefited from effective interventions) is critical. Our belief is that we can use data from longitudinal and experimental investigations to inform early identification and intervention.
What is ADAPT doing about it?
This period of transition during adolescence and young adulthood (i.e., the prodromal or high-risk period), immediately before the formal onset of psychosis, holds the unique potential to both inform etiological conceptualizations of psychotic disorders, and serve as a viable point for early intervention and/or prevention.
To date, the ADAPT lab has specialized in several distinct, but mechanistically related susceptibility markers, behaviors, and symptoms that reflect 1) disordered communication between the subcortical structures that govern basic human function and the frontal regions that underlie higher order functions, 2) abnormalities in medial temporal brain structures and function and 3) dysfunction in emotional systems and dynamic social interaction. We have focused on these phenomena because they appear to interact with developmental and genetic factors, share related neurological underpinnings that also characterize psychosis, directly contribute to poor quality of life (or, if not, can directly inform treatment development efforts), and are quantifiable, potentially enabling a system of early identification and intervention.
Details from each of these studies can be found on the lab publication page.
Basal Ganglia and Cerebellar Circuits
Psychotic disorders are characterized by distinct domains of symptoms as well as emotional, nonverbal, and cognitive deficits drawing upon a host of disparate mechanisms and structures. Our first line of research tests the idea that the basal-ganglia circuits, which are responsible for dynamic communication between the subcortical structures that govern basic functions and the frontal regions that underlie higher order functions (e.g., cognition, perception, motivation/reward, emotion), are a good target for improving our understanding why such a wide variety of functions are affected in psychosis (Figure 5; from Obeso et al.). Current thought holds that markers of dysfunction in one structure or circuit will also be indicative of dysfunction in other loops (as the circuits are governed by the same neurotransmitter systems). Within this context we have been particularly focused on domains of motor behavior (e.g., gesture) and types of movement dysfunction (dyskinesia, soft signs, dyspraxia), as these characteristics reflect basal-ganglia circuit dysfunction as well as dysfunctional integration between the basal ganglia circuits and other relevant domains. Figure 6 illustrates results one of our preliminary studies.
Further, as these circuits are influenced by inflammation, there is significant promise for understanding this work in broader conceptual frameworks. In addition, approaches such as transcranial direction current stimulation (tDCS) hold significant promise for elucidating specific aspects of these circuits and employing novel interventions. In following this line of inquiry, we have also focused on how basal ganglia circuit pathology affects characteristic domains of psychosis including emotion, perception, cognition, and reward. In addition, we have expanded the study in this area to the cerebellar circuits- another critical system that is affected in schizophrenia and believed to govern coordination and balance as well as synchronize cognitive functions (see Figure 7). Our preliminary work in this area suggests that the cerebellar system may account for a unique category of symptoms and cognitive deficits. Our current efforts focus on integrating the two systems to provide a better understanding of unique and overlapping contributions to symptom domains and areas of cognitive function; these efforts hold potential for supplementing traditional observer symptom-based classification system with a biologically based approach (more akin to diagnosis in medicine).
There is a significant translational component to this research program that applies specifically to early identification. As noted, approximately 10-33% of high-risk individuals go on to develop psychosis, but because we don’t know which of the initial cases (who exhibit similar clinical presentations) will be in this group, blanket intervention is not feasible (due to costs and side effects associated with many of the currently available treatments). Our work with biomarker development has significantly helped to improve efforts to identify which individuals in this initial group are most likely to develop psychosis.
We have also been working with researchers to develop tools that can be used to disseminate these findings to clinical settings, and be applied to improve treatment decisions. For example, we are working with a team developing a program for analyzing pen dysfluencies in handwriting (possible to be assessed on any tablet computer), and our preliminary results suggest by focusing on specific markers, we can accurately detect the same movement abnormalities that previously would have required a highly specialized neurological training background (Figure 8). With regard to the cerebellar circuits, we have recently reported findings that suggest that deficits determined by a brief neurological battery can significantly predict abnormalities in cerebellar-thalamic white matter tracts (Figure 9) that are tied to progressively worse symptoms. As a result, clinicians who do not have access to neuroimaging facilities may also be able identify patients in greatest need of intervention. We are also launching new treatment development study, evaluating if cerebellar stimulation is effective in improving verbal working memory deficits in early psychosis. In this context, our lab will be one of the first to utilize tDCS in conjunction with fMRI (participants will receive sham or active stimulation immediately proceeding the scan session), and this approach will provide a significantly improved understanding of how cerebellar-thalamic circuit dysfunction contributes to verbal working memory deficits in psychosis, and further, how brain stimulation modulates activity in this vital circuit. This will help to lay the foundation for innovative new treatments targeting areas that significantly contribute to disability, such as cognition.
Hippocampal Function, Stress, and Exercise Interventions
The hippocampal system, responsible for moderating biological stress reactivity as well as integral cognitive functions, is highly implicated in psychosis as it may serve as an interaction point between the environment and underlying biological susceptibility. Our second line of research focuses on hippocampal development (longitudinal changes in shape, structure/connective tracts, and function) (Figure 10), interactions with psychosocial stress and related hormones such as cortisol (using paradigms involving life-events and expressed emotion/family environment, and Social Stress Tests) and causal factors underlying system vulnerability (e.g., obstetric complications, inflammation). For example, in one longitudinal investigation we found that hippocampal shape anomalies predict a poorer course of illness for those at psychosis risk. Recently, we have also observed that family environment influences resting levels of stress hormones, and that self-concept may moderate this relationship.
There are several translational components to this work that we are particularly enthusiastic about. It is important to consider that while several of the available treatments for individuals at high-risk for psychosis have been found to show some promise in terms of improving prognosis and cognitive function, including cognitive training (which acts upon hippocampal mediated synaptic plasticity). To this end, we have been particularly interested in translating the findings from our longitudinal naturalistic studies into a viable treatment for high-risk youth. Most recently, we have begun to develop a related line of research examining how hippocampal development is effected by physical activity in at-risk youth. Because the hippocampus is a critical structure for de-escalating the stress response, has been found to develop abnormally in high-risk adolescents , and is believed to contribute to cognitive dysfunction, this structure is a key treatment target (Figure 11). If we can harness aerobic exercise, an activity that is widely available, inexpensive, and accompanies few side-effects, this could have a significant public health impact.
An emerging literature suggests that regular aerobic activity can stimulate hippocampal neurogenesis (Figure 12), and we have begun to investigate the potential for an exercise intervention for high-risk youth. In an initial study, we found that high-risk youth engaged in significantly more sedentary but less aerobic activity than controls (assessed with actigraphy over a 5-day period) and that inactivity was associated with smaller medial temporal structures in this group. Following this investigation, we collaborated with Angela Bryan (Co-PI) to propose a related intervention and the study was funded through an innovative translational award that combines a phase 1 stage(to test the underlying mechanism and fine-tune the treatment parameters) and a phase 2 randomized controlled trial (RCT). In this ongoing study (currently in Year 2), we are working to determine if prescribed exercise (monitored exercise for 3 times a week for 12 weeks) will lead to better fitness (V02 Max), hippocampal cell growth, improved episodic memory, and reduced symptoms in this critical population.
We are also preparing to examine if brain derived neurotrophic factor (BDNF) RNA expression changes as a function of aerobic exercise, and if it in turn, mediates the beneficial relationships between exercise and the brain. As exercise may indeed influence factors such as synaptic plasticity, this work has significant potential for future trials conducted in conjunction with treatments involving cognitive training (Figure 13).
Emotion and Social Interaction
As youth at risk for serious mental illness progress in adolescence, insidious deficits in emotional perception, interpretation, and expression begin to interfere with social interaction. This can stunt growth in a time when youth are supposed to be enjoying experiences and learning lessons that help to set the stage for a lifetime. These emotional and social difficulties can also push away support networks and foster isolation and stigma, eventually contributing to course of illness. It is a very important and nuanced area. For example, some core emotional areas appear to be intact in early psychosis (e.g., experience), but others are affected (the extent to which past experiences motivate future behavior); one possibility is that influence from other systems, including deficits in cognition (impacting reward learning), stress sensitivity, or motor impairment (e.g., disrupting efficient or coherent performance of non-verbal communication) may play a role. Our approach, focusing on linking together information from other systems, is ideal for addressing the complexity of these issues. This stems from a heartfelt desire to translate findings from basic research into meaningful interventions that are practical, and can impact public policy. To this end, we have been working to develop a research program examining social processing across domains, and using multiple layers of assessment (e.g., ranging from self-report, to behavior, to complex behavioral interaction, to brain activity).
While working in this area, the lab has become discouraged by the lack of assessment tools that are informed by empirical work. For example, currently available scales conflate behaviors (e.g., not going to parties) with internal experience (this must mean they do not want to go to parties), where in reality, the two are quite separable (e.g., social anxiety might lead to a behavior such as avoiding parties, but the existing scales would mark this as disinterest). We are collaborating with Emory and the University of Georgia (Gregory Strauss) to develop a promising new measure (a preliminary version of the measure can be found here). Along the same lines, we have been very interested in improving traditional questionnaires (which rely solely on self-report or interview based queries) with neuroscience techniques such as electrophysiology (which can provide precise information about timing, which is important in understanding emotional behavior and separating components). In collaboration with Randy Auerbach, our team plans to evaluate three components of reward based processing in a group of adolescents, to group them on this basis of this event related potentials (e.g., high/low reward anticipation, consumption and reward learning), and then to follow them over time to determine clinical and functional outcome ( Figure 14).
The ADAPT team has also been interested in elucidating the basis of social interaction deficits in high-risk youth. The lab has published a number of related studies on social cognition/theory of mind and also looked at non-verbal behaviors such as gesture that may impact communicative ability. We also have examined factors contributing to feelings of peer group isolation. The lab is currently is running a large gesture assessment battery incorporating a data glove, and VR technology to look at these deficits across interpretation as well as perception and action. Most notably, together with Claudia Haase (SEPI), we plan to examine dyadic interaction between adolescents at high-risk and their parents, designed to determine if emotional dysregulation and impacted empathy might predict the course of illness in the adolescents, and immediate and long-term health outcomes in the care-takers(Figure 15).
Finally, ADAPT has been putting a lot of attention into approaching emotional dysfunction from a brain-based perspective. For example, we recently published a report examining the resting state correlates (using salience network seeds) of deficits in facial emotion recognition and are currently running a related eye-tracking paradigm. We have also recently completed a novel social reward fMRI study and begun recruitment for an fMRI study adapting a monetary incentive delay (MID) task for use in high-risk youth. In addition, in an ongoing study, ADAPT is examining the neural basis of facial emotion deficits in youth at risk for psychosis using a novel event related potential paradigm (Figure 16). It is currently unclear if misattribution (seeing angry/fearful instead of happy) or trouble with becoming accustom to familiar faces contributes to s social functioning issues that impact quality of life in many youth at risk for psychosis. This information is vital for developing new treatments as the targets would differ significantly based on early and late deficits in neural processing.
The ADAPT lab specializes in focusing on brain, endocrine, and motor changes during adolescence and young adulthood with the goals of:
- Understanding the role of development in emerging psychopathology
- Identifying biosignatures
- Informing innovative treatments
Our guiding mission is to translate knowledge from basic science approaches to practical and widely disseminable biomarkers and targeted interventions. To accomplish these goals we utilize naturalistic (longitudinal) and experimental behavioral paradigms.
The ADAPT lab employs innovative methodologies for examining our guiding research questions (involving frontal subcortical circuits, hippocampal function, neural/endocrine development, and emotion/social dysregulation) as well as mediating factors (e.g., substance use and inflammation) . Collectively, we employ advanced multi-modal brain imaging (Figure 17), instrumental and VR assessments of movement and cognitive behavior, automated nonverbal behavior and emotive evaluation, hormone analysis (blood, saliva, and hair analysis), transcranial direct current stimulation (tDCS) (see Figure 18), auditory analysis, experienced sampling/actigraphy, stress sensitivity, aerobic fitness assessment (V02 Max), computerized linguistic and semantic analysis, eye tracking (employing paradigms at both 150 and 1000 hz paradigms), electroencephalography (EEG), event related potentionals (ERPs), electromyography (EMG) (Figure 19), dyadic interaction, and inflammatory marker, DNA and RNA analysis. Students interested in working with ADAPT will have the option to work with any of our primary or collaborator-guided methodologies. Participants who prefer to not participate in a particular component are still largely welcome to participate in those areas that they do feel comfortable with.
In addition to the two primarily research lines noted above, we are also interested in several other side studies involving graduate student projects that may eventually develop into more formalized programs and larger grant applications. These fall under the umbrella of the lab mission (promoting etiological understanding and identifying vulnerability makers of risk for developing psychotic disorders), but also reflect substantial student guided interests as well (that they can carry on to their own labs in the future: e.g., sleep, social reward, Internet use, working memory).
The ADAPT lab is also dedicated to improving classification and assessment. To this end we have authored several critical commentaries, reviews, and communications pertaining to the classification of movement abnormalities in psychiatric illness. In addition, the lab works to write peer-reviewed commentaries of assessment issues that are informed by experiences with at-risk youth.
We are also passionate about mental health advocacy and public policy. We are incredibly proud of a collaboration with Elyn Saks (Professor of Law at USC and prestigious mental health advocate) to evaluate ethical and legal dilemmas inherent in disclosing an attenuated psychosis syndrome diagnosis to patients and families and most recently, are editing a special issue of the Journal of Ethics in Mental Health on the topic of ethical considerations surrounding prodromal research and treatment.
Development of a Psychosis Risk Screener for our Broader Communities
Most recently, ADAPT has become very interested in improving our ability to detect psychosis risk in the general population. Currently, we focus entirely on help-seeking individuals, but by the time they come into the clinic it is most often quite late. We would be able to help people more effectively, and understand causes of psychosis better if we could get them identified as early as possible. In collaboration with colleagues at Temple and University of Maryland, we recently received significant funding to evaluate risk markers in 12,000 adolescents across Chicago, Philadelphia and Baltimore. In the first study of its kind, we will focus on using item response theory to develop a short screener that will let teens and practitioners in a variety of primary care or educational settings that more in-depth screening might be required. In addition to being able to develop a helpful insturment, this opportunity will allow for us to develop a cohort that we will propose study, enriching collection and broadening our questions and approaches, for the next two decades.