Evidence of shared familial factors influencing neurocognitive endophenotypes in adult- and childhood-onset schizophrenia

Neurocognitive dysfunctions in childhood-onset schizophrenia: A systematic review

Objective

To conduct a systematic review of neurocognitive dysfunctions in patients with childhood-onset schizophrenia (COS), a neuropsychiatric disorder that occurs before age 13 and is rarer and more severe than adult-onset schizophrenia.

Method

A search was made in the PubMed database. Sixty-seven studies (out of 543) which analyzed Intellectual Quotient (IQ), attentional, memory and executive functions were selected by two independent researchers. Study's appraisal was done according to the Mixed Methods Appraisal Tool (MMAT). This systematic review was registered on PROSPERO (CRD42024548945).

Result

COS shows neurocognitive dysfunction in IQ with mean scores ranging from one to two standard deviation lower than normative data. Attentional deficits are observed with longer reaction time, more errors of omission and commission and slower processing speed than controls. In addition, working memory and executive functions, such as planification and flexibility are impaired. COS exhibit significantly more neurocognitive deficits than adolescent and adult-onset forms and display deterioration in intellectual functioning between premorbid period and after onset of psychosis.

Conclusion

COS is characterized by major cognitive impairments, both before the onset of the disease and throughout its course. As in adult-onset schizophrenia, generalized cognitive impairment is found without the emergence of a specific profile, providing further support for the continuum hypothesis between early-onset and adult-onset schizophrenia. Collaborative research on a larger scale (including meta-analyses) and using complementary approaches (dimensional and multimodal) is needed to gain a better understanding of the cognitive impact of COS and pave the way for more precise and targeted cognitive remediation.

Familiality of the Intelligence Quotient in First Episode Psychosis: Is the Degree of Family Resemblance Associated With Different Profiles?

BACKGROUND AND HYPOTHESIS

There is uncertainty about the relationship between the family intelligence quotient (IQ) deviation and the risk for schizophrenia spectrum disorders (SSD). This study tested the hypothesis that IQ is familial in first episode psychosis (FEP) patients and that their degree of familial resemblance is associated with different profiles.

STUDY DESIGN

The participants of the PAFIP-FAMILIAS project (129 FEP patients, 143 parents, and 97 siblings) completed the same neuropsychological battery. IQ-familiality was estimated through the Intraclass Correlation Coefficient (ICC). For each family, the intra-family resemblance score (IRS) was calculated as an index of familial similarity. The FEP patients were subgrouped and compared according to their IRS and IQ.

STUDY RESULTS

IQ-familiality was low-moderate (ICC = 0.259). A total of 44.9% of the FEP patients had a low IRS, indicating discordancy with their family-IQ. Of these patients, those with low IQ had more schizophrenia diagnosis and a trend towards poorer premorbid adjustment in childhood and early adolescence. Whereas FEP patients with low IQ closely resembling their family-IQ were characterized by having the lowest performance in executive functions.

CONCLUSIONS

The deviation from the familial cognitive performance may be related to a particular pathological process in SSD. Individuals with low IQ who do not reach their cognitive familial potential show difficulties in adjustment since childhood, probably influenced by environmental factors. Instead, FEP patients with high phenotypic family resemblance might have a more significant genetic burden for the disorder.

The age of onset and cognitive impairment at the early stage of schizophrenia

In schizophrenia, the age of first episode onset can reflect genetic loading and predict prognosis. Little is known about the association between the age of onset and cognition among individuals with early-stage schizophrenia. We aimed to compare the pre-treatment neurocognition profile between individuals with early-onset schizophrenia (EOS, the age of onset < 18 years), typical-onset schizophrenia (TOS, the age of onset between 18 and 39 years), and late-onset schizophrenia (LOS, the age of onset between 40 and 59 years). We included individuals with a current diagnosis of schizophrenia within 3 years and medication naive or less than 2 weeks of cumulative antipsychotic exposure and current daily antipsychotic dosage equivalent to ≤ 15 mg of olanzapine. Assessments included the MATRICS Consensus Cognitive Battery (MCCB) and the Positive and Negative Syndrome Scale (PANSS). We used linear regression to compare the difference between age-of-onset groups. We included 356 participants (67 EOS, 195 TOS, and 94 LOS). Compared with LOS, TOS was associated with lower scores in the verbal learning scores of the MCCB after adjusting for education years and the subscale scores of the PANSS (45.5 ± 12.9 vs. 40.5 ± 14.1, adjusted B = - 5.79, p = 0.001). The three groups had no difference in other cognitive domain scores. The association between the age of onset and MCCB verbal memory was U-shape (square of the age of onset, adjusted B = 0.02, p = 0.003). Patients with LOS had a better verbal learning function compared with individuals with TOS. These findings suggest that involvement of cognition assessment and rehabilitation training is necessary for patients with TOS.

Neurocognitive profile of adolescents with early-onset schizophrenia and their unaffected siblings

BACKGROUND

We investigated the neurocognitive profiles of Early-Onset Schizophrenia (EOS; onset before age 18) and paired unaffected siblings and the little-studied effect of age-of-onset and duration of illness on cognitive performance.

METHODS

31 EOS probands, and 31 of their siblings, had four cognitive domains assessed: (a) Memory: California Verbal Learning Test, and the Wechsler Memory Scale-Revised; (b) Working memory: Digit Span; (c) Attention: Degraded-Stimulus Continuous Performance Test, Span of Apprehension (SPAN), and Trail Making Test (TMT) part A; (d) Executive function: Wisconsin card sorting task, and TMT part B. Diagnosis was confirmed using the structured clinical interview for DSM-IV.

RESULTS

While EOS showed a generalised neurocognitive deficit (0.25-0.50 effect size) compared with siblings, across all cognitive domains, significantly greater patient deficits were observed with, working memory, attention, and executive function and minimal differences for digit span forward, block design and false alarms on the SPAN-12 confirmed by repeated measures MANOVA. Patients with earlier onset (12-15) showed greater deficits on false alarm and digits backward scores. Siblings showed individual cognitive task profiles similar to patients, confirming familial effects. EOS showed much more variable scores than siblings with more individual tasks showing 2 SD deficits than siblings. Long duration patients had greater z-score variability across tasks.

CONCLUSIONS

Duration of illness was a more important characteristic in patients with onset 16 and over than in younger onset patients with comparable durations. Both the similarity of sibling pair profiles and greater patient variability across task provide further support for neurobiological heterogeneity in schizophrenia.

[Implementation of the principle of supported employment in Germany : Position paper of a task force of the DGPPN]

The effects of mental diseases on the employment and working situation can be substantial. They are one of the main reasons for inability to work and reduced earning capacity. Against this background the question arises about suitable occupational reintegration measures for people with severe mental illnesses. In recent years, the principle of supported employment has been internationally shown to be increasingly more successful. In this context mentally ill people are primarily placed at a position of the first employment market and supported on-site by a job coach. This concept is inclusive, individual and evidence based. Despite proven effectiveness, it has so far been insufficiently implemented in German-speaking regions. In the future it will be a matter of considering the individual needs for assistance of mentally ill people more intensively than previously and to respond with functional and in a best-case scenario, multiprofessional and flexible offers.

Genetics of Childhood-Onset Schizophrenia: 2019 Update

The genetic architecture of schizophrenia is complex and highly polygenic. This article discusses key findings from genetic studies of childhood-onset schizophrenia (COS) and the more common adult-onset schizophrenia (AOS), including studies of familial aggregation and common, rare, and copy number variants. Extant literature suggests that COS is a rare variant of AOS involving greater familial aggregation of schizophrenia spectrum disorders and a potentially higher occurrence of pathogenic copy number variants. The direct utility of genetics to clinical practice for COS is currently limited; however, identifying common pathways through which risk genes affect brain function offers promise for novel interventions.