Evidence regarding the effects of antipsychotic medication on cognitive functioning after a first-episode psychosis (FEP) remains inconclusive. This study examined whether dopamine D2 receptor occupancy, affinity, and antipsychotic dose are related to cognitive functioning in people in remission from FEP.

278 remitted FEP participants from the HAMLETT-trial were included. Cognitive functioning was assessed with the Brief Assessment of Cognition in Schizophrenia, 3–6 months after remission. D2 receptor occupancy was estimated based on antipsychotic type and dose. Antipsychotics were categorized into partial agonists, or antagonists with high or low D2 receptor affinity. Linear regression analyses were performed with inverse probability of treatment weighting to control for differences in characteristics between groups.

D2 receptor occupancy was negatively related to global cognition (β = −0.18), verbal fluency (β = −0.22), and attention and processing speed (β = −0.17, all p < 0.003). The interaction between daily dose and D2 receptor affinity category was significant for global cognition (p = 0.0046) and working memory (p = 0.0019), but not for verbal fluency after correction for multiple testing (p = 0.029). Interactions showed that higher daily dose was related to lower cognitive functioning, with significantly stronger negative effects in high-affinity antagonists compared to other antipsychotics.

The current findings underscore the importance of antipsychotic D2 receptor occupancy and affinity for cognitive functioning and suggest better cognitive functioning in users of partial agonists and low D2 receptor affinity antipsychotics. This can be important when selecting antipsychotics for individuals with FEP.

After remission of a first-episode psychosis (FEP), antipsychotic discontinuation is associated with an increased risk of relapse compared to maintenance treatment. We studied short and longer-term effects of discontinuation of D2 receptor (D2R) antagonist and partial agonist antipsychotics on striatal dopamine D2/3R availability in FEP patients.

Remitted FEP patients underwent two [11C]raclopride PET scans to measure striatal D2/3R availability: 1 week after antipsychotic discontinuation (n = 16 antagonist users, n = 6 partial agonist users) and after being medication free for 6–8 weeks (n = 8 antagonist users, n = 5 partial agonist users). Fifteen matched healthy controls were scanned once. Psychotic relapse was monitored up to 12 months after discontinuation.

One week after discontinuation, D2R antagonist discontinuers showed higher striatal binding potential (BPND) than partial D2R agonist discontinuers (p < 0.001, CI = 0.749 to 1.681) and controls (p = 0.045, CI = 0.008 to 0.708), while partial agonist discontinuers had significantly lower BPND than controls (p = 0.001, CI = -1.326 to -0.386). 6-8 weeks after discontinuation, former antagonist users showed similar BPND to controls (p > 0.25), whereas former partial agonist users had higher BPND than controls (p = 0.027, CI = 0.069 to 1.085). Participants who discontinued antagonists relapsed more often (81%) than those who discontinued partial agonists (17%)(χ2 = 5.32, p = 0.021).

Discontinuation of partial D2R agonists may affect D2/3R availability differently than discontinuation of antagonists, which might explain the greater relapse risk after tapering antagonists than partial agonist antipsychotics.

Converging lines of evidence implicate an important role for the immune system in schizophrenia. Microglia are the resident immune cells of the central nervous system and have many functions including neuroinflammation, axonal guidance and neurotrophic support. We aimed to provide a quantitative review of in vivo PET imaging studies of microglia activation in patients with schizophrenia compared with healthy controls.

Demographic, clinical and imaging measures were extracted from each study and meta-analysis was conducted using a random-effects model (Hedge's g). The difference in 18-kDa translocator protein (TSPO) binding between patients with schizophrenia and healthy controls, as quantified by either binding potential (BP) or volume of distribution (VT), was used as the main outcome. Sub-analysis and sensitivity analysis were carried out to investigate the effects of genotype, ligand and illness stage.

In total, 12 studies comprising 190 patients with schizophrenia and 200 healthy controls met inclusion criteria. There was a significant elevation in tracer binding in schizophrenia patients relative to controls when BP was used as an outcome measure, (Hedge's g = 0.31; p = 0.03) but no significant differences when VT was used (Hedge's g = −0.22; p = 0.29).

In conclusion, there is evidence for moderate elevations in TSPO tracer binding in grey matter relative to other brain tissue in schizophrenia when using BP as an outcome measure, but no difference when VT is the outcome measure. We discuss the relevance of these findings as well as the methodological issues that may underlie the contrasting difference between these outcomes.

In a large and comprehensively assessed sample of patients with bipolar disorder type I (BDI), we investigated the prevalence of psychotic features and their relationship with life course, demographic, clinical, and cognitive characteristics. We hypothesized that groups of psychotic symptoms (Schneiderian, mood incongruent, thought disorder, delusions, and hallucinations) have distinct relations to risk factors.

In a cross-sectional study of 1342 BDI patients, comprehensive demographical and clinical characteristics were assessed using the Structured Clinical Interview for DSM-IV (SCID-I) interview. In addition, levels of childhood maltreatment and intelligence quotient (IQ) were assessed. The relationships between these characteristics and psychotic symptoms were analyzed using multiple general linear models.

A lifetime history of psychotic symptoms was present in 73.8% of BDI patients and included delusions in 68.9% of patients and hallucinations in 42.6%. Patients with psychotic symptoms showed a significant younger age of disease onset (β = −0.09, t = −3.38, p = 0.001) and a higher number of hospitalizations for manic episodes (F11 338 = 56.53, p < 0.001). Total IQ was comparable between groups. Patients with hallucinations had significant higher levels of childhood maltreatment (β = 0.09, t = 3.04, p = 0.002).

In this large cohort of BDI patients, the vast majority of patients had experienced psychotic symptoms. Psychotic symptoms in BDI were associated with an earlier disease onset and more frequent hospitalizations particularly for manic episodes. The study emphasizes the strength of the relation between childhood maltreatment and hallucinations but did not identify distinct subgroups based on psychotic features and instead reported of a large heterogeneity of psychotic symptoms in BD.