Adolescent attention deficit hyperactivity disorder and susceptibility to psychosis in adulthood: a review of the literature and a phenomenological case report

Risk of Schizophrenia Increases After All Child and Adolescent Psychiatric Disorders: A Nationwide Study

OBJECTIVE

Earlier smaller studies have shown associations between child and adolescent psychiatric disorders and schizophrenia. Particularly, attention-deficit/hyperactivity-disorder and autism have been linked with schizophrenia. However, large-scale prospective studies have been lacking. We, therefore, conducted the first large-scale study on the association between a broad spectrum of child and adolescent psychiatric disorders and the risk of being diagnosed with schizophrenia.

METHODS

Danish nationwide registers were linked to establish a cohort consisting of all persons born during 1990-2000 and the cohort was followed until December 31, 2012. Data were analyzed using survival analyses and adjusted for calendar year, age, and sex.

RESULTS

A total of 25138 individuals with child and adolescent psychiatric disorders were identified, out of which 1232 individuals were subsequently diagnosed with schizophrenia spectrum disorders. The risk of schizophrenia spectrum disorders was highly elevated, particularly within the first year after onset of the child and adolescent psychiatric disorder, and remained significantly elevated >5 years with an incidence rate ratio of 4.93 (95% confidence interval: 4.37-5.54).We utilized the cumulated incidences and found that among persons diagnosed with a child and adolescent psychiatric disorder between the ages 0-13 years and 14-17 years, 1.68% and 8.74 %, respectively, will be diagnosed with a schizophrenia spectrum disorder <8 years after onset of the child and adolescent psychiatric disorder.

CONCLUSIONS

The risk of being diagnosed with schizophrenia spectrum disorders after a child and adolescent psychiatric disorder was significantly increased particularly in the short term but also in the long-term period.

Psychosis in adulthood is associated with high rates of ADHD and CD problems during childhood

BACKGROUND

Patients diagnosed with schizophrenia display poor premorbid adjustment (PPA) in half of the cases. Attention deficit/hyperactivity disorder (ADHD) and conduct disorder (CD) are common child psychiatric disorders. These two facts have not previously been linked in the literature.

AIMS

To determine the prevalence of ADHD/CD problems retrospectively among patients with psychoses, and whether and to what extent the high frequency of substance abuse problems among such patients may be linked to ADHD/CD problems.

METHOD

ADHD and CD problems/diagnoses were retrospectively recorded in one forensic (n = 149) and two non-forensic samples (n = 98 and n = 231) of patients with a psychotic illness: schizophrenia, bipolar or other, excluding drug-induced psychoses.

RESULTS

ADHD and CD were much more common among the patients than in the general population-the odds ratio was estimated to be greater than 5. There was no significant difference in this respect between forensic and non-forensic patients. Substance abuse was common, but substantially more common among patients with premorbid ADHD/CD problems.

CONCLUSIONS

Previous views regarding PPA among patients with a psychotic illness may reflect an association between childhood ADHD/CD and later psychosis. The nature of this association remains uncertain: two disorders sharing some generative mechanisms or one disorder with two main clinical manifestations. Childhood ADHD and particularly CD problems contribute to the high frequency of substance abuse in such groups.

Oligodendroglial alterations and the role of microglia in white matter injury: relevance to schizophrenia

Schizophrenia is a chronic and debilitating mental illness characterized by a broad range of abnormal behaviors, including delusions and hallucinations, impaired cognitive function, as well as mood disturbances and social withdrawal. Due to the heterogeneous nature of the disease, the causes of schizophrenia are very complex; its etiology is believed to involve multiple brain regions and the connections between them, and includes alterations in both gray and white matter regions. The onset of symptoms varies with age and severity, and there is some debate over a degenerative or developmental etiology. Longitudinal magnetic resonance imaging studies have detected progressive gray matter loss in the first years of disease, suggesting neurodegeneration; but there is also increasing recognition of a temporal association between clinical complications at birth and disease onset that supports a neurodevelopmental origin. Presently, neuronal abnormalities in schizophrenia are better understood than alterations in myelin-producing cells of the brain, the oligodendrocytes, which are the predominant constituents of white matter structures. Proper white matter development and its structural integrity critically impacts brain connectivity, which affects sensorimotor coordination and cognitive ability. Evidence of defective white matter growth and compromised white matter integrity has been found in individuals at high risk of psychosis, and decreased numbers of mature oligodendrocytes are detected in schizophrenia patients. Inflammatory markers, including proinflammatory cytokines and chemokines, are also associated with psychosis. A relationship between risk of psychosis, white matter defects and prenatal inflammation is being established. Animal models of perinatal brain injury are successful in producing white matter damage in the brain, typified by hypomyelination and/or dysmyelination, impaired motor coordination and prepulse inhibition of the acoustic startle reflex, recapitulating structural and functional characteristics observed in schizophrenia. In addition, elevated expression of inflammation-related genes in brain tissue and increased production of cytokines by blood cells from patients with schizophrenia indicate immunological dysfunction and abnormal inflammatory responses, which are also important underlying features in experimental models. Microglia, resident immune defenders of the central nervous system, play important roles in the development and protection of neural cells, but can contribute to injury under pathological conditions. This article discusses oligodendroglial changes in schizophrenia and focuses on microglial activity in the context of the disease, in neonatal brain injury and in various experimental models of white matter damage. These include disorders associated with premature birth, and animal models of perinatal bacterial and viral infection, oxygen deprivation (hypoxia) and excess (hyperoxia), and elevated systemic proinflammatory cytokine levels. We briefly review the effects of treatment with antipsychotic and anti-inflammatory agents in models of perinatal brain injury, and comment on the therapeutic potential of these strategies. By understanding the neurobiological basis of oligodendroglial abnormalities in schizophrenia, it is hoped that patients will benefit from the availability of targeted and more efficacious treatment options.