Adolescent schizophrenia: a methodologic review of the current neuroimaging and neuropsychologic literature

Parvalbumin neurons and perineuronal nets in the mouse prefrontal cortex

The prefrontal cortex (PFC) plays a key role in cognitive functions, memory, and attention. Alterations in parvalbumin interneurons (PV neurons) and perineuronal nets (PNNs) within the PFC have been implicated in schizophrenia and autism spectrum disorder pathology. However, it remains unclear why PV neurons and PNNs in the PFC are selectively impaired. Here we aimed to clarify if PV neurons and PNNs in the PFC have region-specific features. We found that PV neurons and PNNs were increased in a region-specific manner in the PFC during postnatal development. In the mature PFC, the expression of PV protein is lower than in other parts of the cortex. Furthermore, PNNs in the mature PFC are not typical lattice-like structures and do not have the major components of PNNs and tenascin-R. The present study indicates that PV neurons and PNNs have region-specific features, and our results suggest that PV neurons and PNNs have structural vulnerability within the PFC.

Clinical and neurocognitive course in early-onset psychosis: a longitudinal study of adolescents with schizophrenia-spectrum disorders

AIM

Adolescents with psychotic disorders show deficits in IQ, attention, learning and memory, executive functioning, and processing speed that are related to important clinical variables including negative symptoms, adaptive functioning and academics. Previous studies have reported relatively consistent deficits with varying relationships to illness status and symptoms. The goals of this study were to examine these relationships in a larger sample at baseline, and also to examine the longitudinal course of these deficits in a smaller subset of adolescents.

METHOD

Thirty-six subjects, aged 10 to 17 years, were included at baseline. All had Diagnostic and Statistical Manual-Fourth Edition diagnoses of schizophrenia, schizoaffective disorder, schizophreniform disorder and psychosis - not otherwise specified, as determined by Kiddie-Schedule for Affective Disorders and Schizophrenia for School-Age Children structured interviews. Patients were administered a neuropsychological battery, and Positive and Negative Syndrome Scale ratings were completed at baseline and again at 1 year (n = 14). Most participants were inpatients at baseline, and 13 of 14 were on atypical antipsychotic medication during both sessions.

RESULTS

At baseline, the patients demonstrated impairments in working memory, processing speed, executive function and verbal learning. No significant cognitive change was detected at 1-year follow-up. In contrast, clinical symptoms were variable across 1 year, with an improvement in positive symptoms at 1 year. No relationships between clinical and cognitive symptoms were observed, with the exception of baseline IQ predicting negative symptoms at 1 year.

CONCLUSIONS

Young patients with schizophrenia-spectrum disorders displayed neurocognitive impairments at baseline. Despite measurable fluctuations in clinical symptoms over the year, no significant changes were measured in cognition. Lower IQ at baseline was predictive of more negative symptoms at 1 year.

Autismus und Stoffwechselerkrankungen - was ist gesichert?

Zusammenfassung: Die Ursachen für Autismus sind heterogen und ganz überwiegend genetischer Natur. Eine exakte benennbare Ätiologie wird in weniger als 10% der Fälle gefunden. Die Enttäuschung über den geringen Erfolg bei der Ursachenfindung und zahlreiche Berichte über die Assoziation von Autismus mit Stoffwechselerkrankungen sowie über «Wunderheilungen» bei unterschiedlichsten medikamentösen oder diätetischen Therapien haben bei vielen Ärzten und Eltern zu einer zunehmenden Unsicherheit über die sinnvolle Diagnostik und Behandlung geführt. Diese Arbeit gibt einen Überblick über seltene angeborene Stoffwechselerkrankungen («inborn errors of metabolism»), die nachweislich (z.B. Phenylketonurie, Smith-Lemli-Opitz Syndrom) oder wahrscheinlich (z.B. Succinat-Semialdehyd-Dehydrogenase-Mangel) mit Autismus-spezifischen Symptomen vergesellschaftet sind. In aller Regel weisen betroffene Patienten zusätzliche neurologische Symptome auf. Es werden die zur Diagnostik dieser angeborenen Stoffwechselerkrankungen notwendigen Untersuchungen und mögliche therapeutische Maßnahmen dargestellt. Neben diesen gut definierten Stoffwechselerkrankungen mit der Möglichkeit einer rationalen Therapie wird auch auf Hypothesen über die Entstehung von Autismus durch «Stoffwechselveränderungen» eingegangen, die entweder nicht bewiesen oder nachweislich falsch sind.

The neurodevelopmental model of schizophrenia: update 2005

Neurodevelopmental models of schizophrenia that identify longitudinal precursors of illness have been of great heuristic importance focusing most etiologic research over the past two decades. These models have varied considerably with respect to specificity and timing of hypothesized genetic and environmental 'hits', but have largely focused on insults to prenatal brain development. With heritability around 80%, nongenetic factors impairing development must also be part of the model, and any model must also account for the wide range of age of onset. In recent years, longitudinal brain imaging studies of both early and adult (to distinguish from late ie elderly) onset populations indicate that progressive brain changes are more dynamic than previously thought, with gray matter volume loss particularly striking in adolescence and appearing to be an exaggeration of the normal developmental pattern. This supports an extended time period of abnormal neurodevelopment in schizophrenia in addition to earlier 'lesions'. Many subtle cognitive, motor, and behavioral deviations are seen years before illness onset, and these are more prominent in early onset cases. Moreover, schizophrenia susceptibility genes and chromosomal abnormalities, particularly as examined for early onset populations (ie GAD1, 22q11DS), are associated with premorbid neurodevelopmental abnormalities. Several candidate genes for schizophrenia (eg dysbindin) are associated with lower cognitive abilities in both schizophrenic and other pediatric populations more generally. Postmortem human brain and developmental animal studies document multiple and diverse effects of developmental genes (including schizophrenia susceptibility genes), at sequential stages of brain development. These may underlie the broad array of premorbid cognitive and behavioral abnormalities seen in schizophrenia, and neurodevelopmental disorders more generally. Increased specificity for the most relevant environmental risk factors such as exposure to prenatal infection, and their interaction with susceptibility genes and/or action through phase-specific altered gene expression now both strengthen and modify the neurodevelopmental theory of schizophrenia.

Nurture: the fundamental significance of relationship as a paradigm for mental health nursing

TOPIC

Whether nature or nurture is the most appropriate paradigm for mental health nursing practice, education, and research.

PURPOSE

To present detailed information that nurture is the most inclusive and sustaining paradigm for mental health nursing.

SOURCES

Published literature.

CONCLUSIONS

Psychological, social, cultural, environmental, biological, and experience-based problems are the root of mental illness. Mental health nursing must have a comprehensive paradigm that honors the relational nature of the nurse-patient relationship, the critical influence of environment, the importance of biological factors, and the way that narrative understanding and history shape behavior.

An MRI study of adolescent patients with either schizophrenia or bipolar disorder as compared to healthy control subjects

BACKGROUND

There are few imaging studies in adolescent patients with either schizophrenia or bipolar disorder. Such studies are of interest because adolescents may have a more severe illness and neurodevelopmental events may have a greater role in their pathophysiology.

METHODS

We compared 20 patients with schizophrenia and 15 patients with bipolar disorder (10 to 18 years) to 16 normal adolescents on magnetic resonance imaging (MRI) measures of intracranial volume and ventricular and sulcal enlargement. Two planned comparison contrasts were employed, one comparing the two patient groups to each other (contrast 1), and one comparing both patient groups combined to control subjects (contrast 2).

RESULTS

None of the contrast 1 comparisons (schizophrenia vs bipolar) were statistically significant. Contrast 2 comparisons (control subjects vs patients) were statistically significant for intracranial volume (reduced in patients) as well as frontal and temporal sulcal size (increased in patients).

CONCLUSIONS

The patient groups were not statistically significantly different from each other on any measure. The combined patient groups were different from control subjects on intracranial volume and frontal and temporal sulcal size. Also, there was evidence for ventricular enlargement, after removal of a control subject with an extreme value. These findings indicate that the same abnormalities noted in adult populations are present in adolescents.