A longitudinal study of schizophrenia in adolescence. I. The one- to three-year outcome

Perineuronal Nets in the Prefrontal Cortex of a Schizophrenia Mouse Model: Assessment of Neuroanatomical, Electrophysiological, and Behavioral Contributions

Schizophrenia is a neurodevelopmental disorder whose etiopathogenesis includes changes in cellular as well as extracellular structures. Perineuronal nets (PNNs) associated with parvalbumin-positive interneurons (PVs) in the prefrontal cortex (PFC) are dysregulated in schizophrenia. However, the postnatal development of these structures along with their associated neurons in the PFC is unexplored, as is their effects on behavior and neural activity. Therefore, in this study, we employed a DISC1 (Disruption in Schizophrenia) mutation mouse model of schizophrenia to assess these developmental changes and tested whether enzymatic digestion of PNNs in the PFC affected schizophrenia-like behaviors and neural activity. Developmentally, we found that the normal formation of PNNs, PVs, and colocalization of these two in the PFC, peaked around PND 22 (postnatal day 22). However, in DISC1, mutation animals from PND 0 to PND 60, both PNNs and PVs were significantly reduced. After enzymatic digestion of PNNs with chondroitinase in adult animals, the behavioral pattern of control animals mimicked that of DISC1 mutation animals, exhibiting reduced sociability, novelty and increased ultrasonic vocalizations, while there was very little change in other behaviors, such as working memory (Y-maze task involving medial temporal lobe) or depression-like behavior (tail-suspension test involving processing via the hypothalamic pituitary adrenal (HPA) axis). Moreover, following chondroitinase treatment, electrophysiological recordings from the PFC exhibited a reduced proportion of spontaneous, high-frequency firing neurons, and an increased proportion of irregularly firing neurons, with increased spike count and reduced inter-spike intervals in control animals. These results support the proposition that the aberrant development of PNNs and PVs affects normal neural operations in the PFC and contributes to the emergence of some of the behavioral phenotypes observed in the DISC1 mutation model of schizophrenia.

A systematic review of the long-term outcome of early onset schizophrenia

BACKGROUND

The current review analyzes the long-term outcome and prognosis of early onset schizophrenia based on previously published studies in 1980.

METHODS

A systematic search of articles published in the English-language literature after 1980 identified a total of 21 studies, which included 716 patients who were either suffering from early onset schizophrenia (EOS) or both EOS and other psychotic disorders (MIX). The authors of the current review scored the outcome as either "good," "moderate," or "poor." The mean age of onset in these studies was <18 years.

RESULTS

In general, the outcome in studies with EOS is worse than the outcome in MIX studies. Only 15.4% of the patients in EOS studies versus 19.6% of the patients in MIX studies experienced a "good" outcome. In contrast, 24.5% of the patients in EOS studies versus 33.6% in MIX studies experienced a "moderate" outcome, and 60.1% in EOS studies versus 46.8% in MIX studies experienced a "poor" outcome. The authors identified various significant effects on outcome. In EOS, the findings were significantly affected by sample attrition, indicating that in studies with a high dropout rate, fewer patients experienced a "moderate" outcome, and more patients experienced a "poor" outcome; however, the effect sizes were small. Furthermore, the effects were also small and more favourable for specific functioning measures, as opposed to more global measures, small to moderate in terms of worse outcomes for follow-up periods >10 years, small to moderate for more unfavourable outcomes in males, and small to large for worse outcomes in studies including patients diagnosed before 1970.

CONCLUSIONS

In contrast to the adult manifestation, the early manifestation of schizophrenia in childhood and adolescence still carries a particularly poor prognosis. According to these aggregated data analyses, longer follow-up periods, male sex, and patients having been diagnosed before 1970 contribute predominantly to the rather poor course of EOS.