Although language deficits have often been reported in schizophrenia, the specific relevance of single linguistic levels of processing is still under debate. Moreover, little is known about language disturbances in bipolar disorder.

The aims of this study were to:

1. 1) investigate micro-linguistic (lexicon, morphology, syntax) and macro-linguistic (discourse coherence, pragmatics) dimensions of speech production and

2. 2) evaluate syntactic comprehension skills in both schizophrenia and, for the first time, bipolar disorder.

A story telling task and a computer-based test of syntactic comprehension were administered to 30 Italian speaking DSM-IV patients suffering from schizophrenia, 30 participants with bipolar disorder and 30 healthy controls, comparable for age and educational level (p>0.05). Analysis of variance with post-hoc correction was performed to compare linguistic performance between groups.

In comparison to healthy participants, patients with schizophrenia had significantly impaired productivity, syntactic complexity and local/global discourse coherence and bipolar disorder subjects showed deficits in mean length of utterance (p< 0.05). Also, both groups of patients collected more grammatical errors than controls (p< 0.05), but they differed in regard to the grammatical type of construction they missed (passive-affirmative and active-negative, respectively).

Our results showed the presence of both micro and macro-linguistic deficits in linguistic production in schizophrenia, but not in bipolar disorder, suggesting that these abnormalities are specific for schizophrenia. On the contrary, syntactic construction comprehension was altered in both schizophrenia and bipolar disorder, potentially representing the target of innovative rehabilitation strategies.

Language disturbances, such as impoverishment, disorganization and dysregulation, are a prominent feature of schizophrenia. Several neuroimaging studies have suggested the superior temporal gyrus (STG) as a likely anatomical substrate of language deficits in schizophrenia. The aim of this study was to verify a correlation between structural measures of STG and Heschl's gyrus (HG) and language dimensions.

An extensive language examination battery, which included narrative and conversational expressive tasks, and syntactic and pragmatic comprehension tests, was administered to 23 schizophrenia patients (mean age±SD= 40.30±11.60) and 21 normal controls (mean age±SD= 42.19±11.05). All subjects also underwent a 1.5T MRI session, and STG and HG were manually traced and volumes were obtained, bilaterally, using Brains2.

Specific language deficits were shown in subjects with schizophrenia compared to healthy individuals (p<0.001), particularly in verbal fluency, syntactic complexity, lexical diversity and metaphor/idiom comprehension. Interestingly, speech fluency significantly directly associated with left STG gray matter volumes in controls (r=0.46, p=0.03) but not in patients (r=-0.27, p=0.21). In contrast, complex syntax and word diversity significantly correlated, respectively, with left and right HG volumes in schizophrenia patients (r=0.45, p=0.02; r=-0.47, p=0.02), but not in controls (p>0.05).

This study confirmed a widespread impairment of language in schizophrenia. Interestingly, distinct language dimensions differently correlated with STG-HG volumes in patients with schizophrenia and controls, particularly with regard to verbal fluency and syntactic measures.

Abnormalities in incentive decision making, typically assessed using the Iowa Gambling Task (IGT), have been reported in both schizophrenia (SZ) and bipolar disorder (BD). We applied the Expectancy–Valence (E–V) model to determine whether motivational, cognitive and response selection component processes of IGT performance are differentially affected in SZ and BD.

Performance on the IGT was assessed in 280 individuals comprising 70 remitted patients with SZ, 70 remitted patients with BD and 140 age-, sex- and IQ-matched healthy individuals. Based on the E–V model, we extracted three parameters, ‘attention to gains or loses’, ‘expectancy learning’ and ‘response consistency’, that respectively reflect motivational, cognitive and response selection influences on IGT performance.

Both patient groups underperformed in the IGT compared to healthy individuals. However, the source of these deficits was diagnosis specific. Associative learning underlying the representation of expectancies was disrupted in SZ whereas BD was associated with increased incentive salience of gains. These findings were not attributable to non-specific effects of sex, IQ, psychopathology or medication.

Our results point to dissociable processes underlying abnormal incentive decision making in BD and SZ that could potentially be mapped to different neural circuits.