Psychiatry Articles

Reduced duration mismatch negativity in adolescents with psychotic symptoms: further evidence for mismatch negativity as a possible biomarker for vulnerability to psychosis.

Jennifer R. Murphy et al. — Tue, 30 Apr 2013 06:39:08 PDT

BACKGROUND: Deficits in the mismatch negativity (MMN) and P3a components are the most reliable and robust findings in schizophrenia. These abnormalities have also been recently documented in individuals clinically at risk for psychosis, indicating that the MMN may be a potential biomarker for psychosis. However, the at risk samples included in MMN studies are characterised by pre-existing clinical symptomatology and significant functional decline which are related to MMN amplitude. These factors may be potential confounds in determining whether deficient MMN is present prior to clinical manifestation of the disorder. Therefore, investigating the MMN in the extended psychosis phenotype comprising adolescents with psychotic symptoms from the general population may provide important information on whether abnormal MMN is apparent in the earliest stages of risk.

METHODS: Thirty six adolescents completed a duration deviant MMN task. Fourteen adolescents with psychotic symptoms comprised the at risk group and 22 with no psychotic symptoms comprised the Controls. The task consisted of 85% standard tones (25 ms) and 15% deviant tones (50 ms). The groups were compared on MMN and P3a amplitude and latency across frontocentral and temporal electrodes.

RESULTS: Adolescents with psychotic symptoms were characterised by a reduction in MMN amplitude at frontal and temporal regions compared to the controls.

CONCLUSIONS: This is the first study to demonstrate impaired auditory discrimination for duration deviant tones in nonclinical adolescents with psychotic symptoms. These findings suggest that MMN amplitude may be a possible biomarker for vulnerability to psychosis.

Identification and characterization of prodromal risk syndromes in young adolescents in the community: a population-based clinical interview study.

Ian Kelleher et al. — Wed, 20 Feb 2013 09:16:36 PST

While a great deal of research has been conducted on prodromal risk syndromes in relation to help-seeking individuals who present to the clinic, there is a lack of research on prodromal risk syndromes in the general population. The current study aimed first to establish whether prodromal risk syndromes could be detected in non-help-seeking community-based adolescents and secondly to characterize this group in terms of Axis-1 psychopathology and general functioning. We conducted in-depth clinical interviews with a population sample of 212 school-going adolescents in order to assess for prodromal risk syndromes, Axis-1 psychopathology, and global (social/occupational) functioning. Between 0.9% and 8% of the community sample met criteria for a risk syndrome, depending on varying disability criteria. The risk syndrome group had a higher prevalence of co-occurring nonpsychotic Axis-1 psychiatric disorders (OR = 4.77, 95% CI = 1.81-12.52; P < .01) and poorer global functioning (F = 24.5, df = 1, P < .0001) compared with controls. Individuals in the community who fulfill criteria for prodromal risk syndromes demonstrate strong similarities with clinically presenting risk syndrome patients not just in terms of psychotic symptom criteria but also in terms of co-occurring psychopathology and global functioning.

Fragile X syndrome: a pilot proton magnetic resonance spectroscopy study in premutation carriers.

Brian P. Hallahan et al. — Mon, 17 Sep 2012 04:09:05 PDT

ABSTRACT: PurposeThere is increasing evidence that neurodevelopmental differences in people with Fragile X syndrome (FraX) may be explained by differences in glutamatergic metabolism. Premutation carriers of FraX were originally considered to be unaffected although several recent reports demonstrate neuroanatomical, cognitive, and emotional differences from controls. However there are few studies on brain metabolism in premutation carriers of FraX. METHODS: We used proton magnetic resonance spectroscopy to compare neuronal integrity of a number of brain metabolites including N-Acetyl Aspartate, Creatine + Phosphocreatinine, Choline, myoInositol, and Glutamate containing substances (Glx) in 17 male premutation carriers of FraX and 16 male healthy control individuals. RESULTS: There was no significant between-group difference in the concentration of any measured brain metabolites. However there was a differential increase in N-acetyl aspartate with aging in premutation FraX individuals compared to controls. CONCLUSIONS: This is the first 1 H-MRS study to examine premutation FraX individuals. Although we demonstrated no difference in the concentration of any of the metabolites examined between the groups, this may be due to the large age ranges included in the two samples. The differential increase in NAA levels with aging which may reflect an abnormal synaptic pruning process.

Psychotic-like experiences in the general population: characterizing a high-risk group for psychosis.

Ian Kelleher et al. — Wed, 08 Feb 2012 09:48:43 PST

Recent research shows that psychotic symptoms, or psychotic-like experiences (PLEs), are reported not only by psychosis patients but also by healthy members of the general population. Healthy individuals who report these symptoms are considered to represent a non-clinical psychosis phenotype, and have been demonstrated to be at increased risk of schizophrenia-spectrum disorder. Converging research now shows that this non-clinical psychosis phenotype is familial, heritable and covaries with familial schizophrenia-spectrum disorder. A review of the research also shows that the non-clinical phenotype is associated extensively with schizophrenia-related risk factors, including social, environmental, substance use, obstetric, developmental, anatomical, motor, cognitive, linguistic, intellectual and psychopathological risk factors. The criterion and construct validity of the non-clinical psychosis phenotype with schizophrenia demonstrates that it is a valid population in which to study the aetiology of psychosis. Furthermore, it suggests shared genetic variation between the clinical and non-clinical phenotypes. Much remains to be learned about psychosis by broadening the scope of research to include the non-clinical psychosis phenotype.

Prevalence of psychotic symptoms in childhood and adolescence: a systematic review and meta-analysis of population-based studies.

Ian Kelleher et al. — Wed, 08 Feb 2012 09:25:15 PST

BACKGROUND: Psychotic symptoms occur more frequently in the general population than psychotic disorder and index risk for psychopathology. Multiple studies have reported on the prevalence of these symptoms using self-report questionnaires or clinical interviews but there is a lack of consensus about the prevalence of psychotic symptoms among children and adolescents.MethodWe conducted a systematic review of all published literature on psychotic symptom prevalence in two age groups, children aged 9-12 years and adolescents aged 13-18 years, searching through electronic databases PubMed, Ovid Medline, PsycINFO and EMBASE up to June 2011, and extracted prevalence rates. RESULTS: We identified 19 population studies that reported on psychotic symptom prevalence among children and adolescents. The median prevalence of psychotic symptoms was 17% among children aged 9-12 years and 7.5% among adolescents aged 13-18 years. CONCLUSIONS: Psychotic symptoms are relatively common in young people, especially in childhood. Prevalence is higher in younger (9-12 years) compared to older (13-18 years) children.