Periodic Reporting for period 1 - DynaT (Dynamics of thought and thought disorders)
Okres sprawozdawczy: 2021-10-01 do 2023-09-30
Communication relies on an alignment of meaning. For example, when talking about something as mundane as daily routine, we tend to think about things like morning preparations, meals, work, family time, and sleep. An overlap in these associations fosters a sense of understanding and connection among interlocutors. Occasionally, a topic can evoke atypical or entirely random associations, which other people find hard to understand. In psychopathology, incoherent communication is central to a diagnostic ascription of Formal Thought Disorder, where it is assumed to reflect the disorganization of thought processes. Formal Thought Disorder is associated with higher illness severity, poor prognosis, and impairments in social and global functioning, yet it remains one of the least understood symptoms in psychosis (all the more so in other disorders), with no established treatments.
One key open issue is that most research on formal thought disorder focuses on communication impairments and not on actual thoughts. Indeed, elucidating covert thought dynamics is a challenging endeavor since thought processes cannot be measured directly. The overall aim of 'Dynamics of thought and thought disorders' (DynaT) was to study mechanisms of formal thought disorder, and dissociate impairments in thought dynamics from impairments in the communication or expression of thought, through the use of state-of-the-art methods, including mathematical modeling and machine learning analysis of neural activity.
To achieve this overarching aim, DynaT pursued three specific objectives investigated in three separate studies. The first specific objective focused on the analysis of mechanisms of formal thought disorder in psychosis, particularly focusing on the interaction between abnormalities in associative memory structure (i.e. are concepts linked to one another in an abnormal way?), its retrieval (whether a concept meaningfully constrains the retrieval of another concept), and the monitoring and regulation of speech (i.e. how well can people withhold the expression of atypical associations or incoherent thoughts). The second specific objective focused on elucidating the finding that people with formal thought disorder often have difficulty disengaging from dominant local associations that intrude the stream of speech and disrupt the global communicative intent (e.g. "my mother, father, son, and Holy Ghost"). The third specific objective of DynaT involved investigating whether other people without psychosis who suffer from any psychiatric symptoms can also exhibit incoherence in thought or speech.
One key open issue is that most research on formal thought disorder focuses on communication impairments and not on actual thoughts. Indeed, elucidating covert thought dynamics is a challenging endeavor since thought processes cannot be measured directly. The overall aim of 'Dynamics of thought and thought disorders' (DynaT) was to study mechanisms of formal thought disorder, and dissociate impairments in thought dynamics from impairments in the communication or expression of thought, through the use of state-of-the-art methods, including mathematical modeling and machine learning analysis of neural activity.
To achieve this overarching aim, DynaT pursued three specific objectives investigated in three separate studies. The first specific objective focused on the analysis of mechanisms of formal thought disorder in psychosis, particularly focusing on the interaction between abnormalities in associative memory structure (i.e. are concepts linked to one another in an abnormal way?), its retrieval (whether a concept meaningfully constrains the retrieval of another concept), and the monitoring and regulation of speech (i.e. how well can people withhold the expression of atypical associations or incoherent thoughts). The second specific objective focused on elucidating the finding that people with formal thought disorder often have difficulty disengaging from dominant local associations that intrude the stream of speech and disrupt the global communicative intent (e.g. "my mother, father, son, and Holy Ghost"). The third specific objective of DynaT involved investigating whether other people without psychosis who suffer from any psychiatric symptoms can also exhibit incoherence in thought or speech.
The three specific objectives of DynaT were pursued in three separate studies.
First, to examine the mechanisms of formal thought disorder, we asked people with schizophrenia and matched, non-psychiatric controls to generate free association to word cues while their brain activity was recorded. We examined the likelihood of generating atypical, idiosyncratic associations, the extent to which participants themselves rated their associations as strong and appropriate, and the speed with which participants reported associations. As expected, we found that patients with psychosis are more likely to generate idiosyncratic associations and are more likely to experience their own associations as relatively weak. However, patients who also showed marked incoherence in speech (formal thought disorder) generated more idiosyncratic associations but did not experience their associations as inappropriate, suggesting that they lack insight regarding the incoherence of their speech and associations. This conclusion was supported by mathematical modeling and analysis of neural activity, which suggested that patients with severe formal thought disorder have an abnormal associative memory structure, whereas those patients who do not have a thought disorder have a primary difficulty in inhibiting the expression of unsuitable associations (despite having some awareness that these associations are indeed unsuitable).
Second, to examine the mechanisms underlying excessive reliance on `local associations`, we exploited recent advances in generative language modeling (e.g. GPT) to show that such excessive reliance on local associations can be reliably explained by an impairment in contextual memory, such that as speech progresses it becomes less and less dependent on its original goal. We also demonstrate how these findings can guide future studies using natural language processing in the study of formal thought disorder.
Third, to study individual differences in the coherence of thought and speech, we ran a large, internet-based study where we asked people about a diverse set of psychiatric symptoms, and measured the coherence of free narratives and associations they were asked to generate. The results of this pioneering study revealed that the core mechanism underlying formal thought disorder is more widespread than commonly assumed while also showing a degree of specificity to particular dimensions of psychopathology. Specifically, we found a specific dimension (self-reported Eccentricity) characterized by disorganized thinking and dysregulated thought expression, leading to atypical and incoherent use of language. Conversely, another specific dimension (Suspiciousness and difficulty confiding in other people) was characterized by concealed disorganized thinking that had no effects on the use of language due to increased monitoring and regulation.)
The findings of these studies were presented in several major scientific conferences, communicated to the general public through Twitter and Clubhouse, and either published or are in the process of being published.
First, to examine the mechanisms of formal thought disorder, we asked people with schizophrenia and matched, non-psychiatric controls to generate free association to word cues while their brain activity was recorded. We examined the likelihood of generating atypical, idiosyncratic associations, the extent to which participants themselves rated their associations as strong and appropriate, and the speed with which participants reported associations. As expected, we found that patients with psychosis are more likely to generate idiosyncratic associations and are more likely to experience their own associations as relatively weak. However, patients who also showed marked incoherence in speech (formal thought disorder) generated more idiosyncratic associations but did not experience their associations as inappropriate, suggesting that they lack insight regarding the incoherence of their speech and associations. This conclusion was supported by mathematical modeling and analysis of neural activity, which suggested that patients with severe formal thought disorder have an abnormal associative memory structure, whereas those patients who do not have a thought disorder have a primary difficulty in inhibiting the expression of unsuitable associations (despite having some awareness that these associations are indeed unsuitable).
Second, to examine the mechanisms underlying excessive reliance on `local associations`, we exploited recent advances in generative language modeling (e.g. GPT) to show that such excessive reliance on local associations can be reliably explained by an impairment in contextual memory, such that as speech progresses it becomes less and less dependent on its original goal. We also demonstrate how these findings can guide future studies using natural language processing in the study of formal thought disorder.
Third, to study individual differences in the coherence of thought and speech, we ran a large, internet-based study where we asked people about a diverse set of psychiatric symptoms, and measured the coherence of free narratives and associations they were asked to generate. The results of this pioneering study revealed that the core mechanism underlying formal thought disorder is more widespread than commonly assumed while also showing a degree of specificity to particular dimensions of psychopathology. Specifically, we found a specific dimension (self-reported Eccentricity) characterized by disorganized thinking and dysregulated thought expression, leading to atypical and incoherent use of language. Conversely, another specific dimension (Suspiciousness and difficulty confiding in other people) was characterized by concealed disorganized thinking that had no effects on the use of language due to increased monitoring and regulation.)
The findings of these studies were presented in several major scientific conferences, communicated to the general public through Twitter and Clubhouse, and either published or are in the process of being published.
DynaT endeavored to face the long-standing challenge of studying the 'stream of thought' without relying on introspection, through the combination of a novel mathematical modeling framework and state-of-the-art decoding of neural activity. The novelty of DynaT is in applying these advanced methods to gain insight into the otherwise hard-to-access dynamics governing covert thoughts in formal thought disorder. The conducted studies revealed several novel insights concerning the mechanisms of formal thought disorder in people with psychosis, as well as the general public where it appears in a milder form. These insights have important clinical, theoretical,and societal implications. For example, the finding that people psychosis have different mechanisms explaining abnormal associative thinking can help advance novel therapeutic and preventive approaches. Furthermore, the finding that mild incoherence in communication and disorganization of thought (even if concealed) occurs in the general population and not only in patients with psychosis can help reduce stigma concerning psychosis and mental health.