Age-related differences in formal thought disorder in chronically hospitalized schizophrenic patients: a cross-sectional study across nine decades

Abstract

F ormal thought disorder is one of the most common symptoms in schizophrenia (1) and one of the most disabling. Severe impairments in communication characterize patients who are particularly unable to care for themselves and who have long periods of psychiatric care (2). Although formal thought disorder is now known to be present in other disorders, especially psychotic affective disorders (3-5), it is present in schizophrenia throughout the illness, including during periods of relative remission of other psychotic symptoms. For instance, schizophrenic patients who have only residual symptoms manifest continued impairments in communication, including deficient verbal productivity (6) and impaired connectedness of speech (7). These two dimensions of communication impairment, impaired connectedness ("positive thought disorder" or "disconnection") and reduced verbal output ("poverty of speech" or "alogia"), have been found in several different studies of schizophrenic patients, including studies that used exploratory and confirmatory factor analysis (8-13). While exploratory studies often have found three dimensions of communication disorder (8, 9), a confirmatory factor analytic study found that a two-dimensional model-verbal productivity and disconnection-is most parsimonious (10). When these findings are extrapolated to broader studies of the organizational structure of schizophrenic symptoms, reduced verbal productivity and greater tendencies toward disconnection in speech correlate with symptom factors referred to as "negative symptoms" and "disorganization," respectively (11-13). In the most recent of these studies (11), of all thought disorders examined, only the severity of derailment was correlated significantly with the severity of positive symptoms, including delusions and hallucinations.Regardless of its factor structure, formal thought disorder has not been studied much across the lifespan of schizophrenic patients. Since formal thought disorder is apparently quite stable over time and clinical state in younger schizophrenic patients, aging-related changes could be expected to be minimal. Other evidence sug-

Latent semantic variables are associated with formal thought disorder and adaptive behavior in older inpatients with schizophrenia

“…It should be noted that cognition and functioning were reported to have the same global correlations in acutely ill and institutionalized older patients (Harvey et al, 1998). However, this age-range is also a unique strength of the current study as previous literature demonstrates that there are age-based differences in performance on verbal fluency tasks (Bowie et al, 2005; Harvey, et al, 1997; Troyer et al, 1997) highlighting the importance of considering differential predictors of performance across the lifespan. A comprehensive assessment of cognitive functioning was not employed in this study, thereby precluding the possibility of comprehensively evaluating the contribution of underlying neurocognitive mechanisms that contribute to the pathogenesis of disorganized discourse.…”

“…Indeed, patients with more severe negative symptoms generate fewer words overall (Allen et al, 1993). In older samples, patients who have a more chronic course of illness demonstrate more impairments than younger patients (Harvey et al, 1997) and there is a pattern of longitudinal worsening in verbal productivity that is predicted by concurrent cognitive worsening (Bowie et al, 2005). …”

Thought, language, and communication deficits and association with everyday functional outcomes among community-dwelling middle-aged and older adults with schizophrenia

“…TLC_DS is calculated as a mean of a six items representing loose or incoherent speech (e.g., tangentiality, circumstantiality), while TLC_VU was defined by the poverty of speech item. This use of the TLC measure has demonstrated adequate-to-good interrater reliability (Bowie et al, 2005; Bowie & Harvey, 2008; Harvey et al, 1997).…”

Update on the development of lurasidone as a treatment for patients with acute schizophrenia

“…In schizophrenia, neurocognition is the most robust predictor of current functional status 60–62. In fact, some research suggests that neurocognition is more consistently related to functioning than symptom severity 63,64.…”