School achievements and schizophrenia: a case-control study

Academic achievement and schizophrenia: a systematic meta-analysis

BACKGROUND

Cognitive impairments in childhood are associated with increased risk of schizophrenia in later life, but the extent to which poor academic achievement is associated with the disorder is unclear.

METHODS

Major databases were searched for articles published in English up to 31 December 2019. We conducted random-effects meta-analyses to: (1) compare general academic and mathematics achievement in youth who later developed schizophrenia and those who did not; (2) to examine the association between education level achieved and adult-onset schizophrenia; and, (3) compare general academic achievement in youth at-risk for schizophrenia and typically developing peers. Meta-regression models examined the effects of type of academic assessment, educational system, age at assessment, measurement of educational level attained, school leaving age, and study quality on academic achievement and education level among individuals with schizophrenia.

RESULTS

Meta-analyses, comprising data of over four million individuals, found that: (1) by age 16 years, those who later developed schizophrenia had poorer general academic (Cohen's d = -0.29, p ⩽ 0.0001) and mathematics achievement (d = -0.23, p = 0.01) than those who did not; (2) individuals with schizophrenia were less likely to enter higher education (odds ratio = 0.49, p ⩽ 0.0001); and, (3) youth reporting psychotic-like experiences and youth with a family history of schizophrenia had lower general academic achievement (d = -0.54, p ⩽ 0.0001; d = -0.39, p ⩽ 0.0001, respectively). Meta-regression analyses determined no effect modifiers.

DISCUSSION

Despite significant heterogeneity across studies, various routinely collected indices of academic achievement can identify premorbid cognitive dysfunction among individuals who are vulnerable for schizophrenia, potentially aiding the early identification of risk in the population.

Terminology and assessment tools of psychosis: A systematic narrative review

AIM

Phenomena within the psychosis continuum that varies in frequency/duration/intensity have been increasingly identified. Different terms describe these phenomena, however there is no standardization within the terminology. This review evaluated the definitions and assessment tools of seven terms - (i) 'psychotic experiences'; (ii) 'psychotic-like experiences'; (iii) 'psychotic-like symptoms'; (iv) 'attenuated psychotic symptoms'; (v) 'prodromal psychotic symptoms'; (vi) 'psychotic symptomatology'; and (vii) 'psychotic symptoms'.

METHODS

EMBASE, MEDLINE, and CINAHL were searched during February-March 2019. Inclusion criteria included 1989-2019, full text, human, and English. Papers with no explicit definition or assessment tool, duplicates, conference abstracts, systematic reviews, meta-analyses, or no access were excluded.

RESULTS

A total of 2238 papers were identified and of these, 627 were included. Definitions and assessment tools varied, but some trends were found. Psychotic experiences and psychotic-like experiences were transient and mild, found in the general population and those at-risk. Psychotic-like symptoms were subthreshold and among at-risk populations and non-psychotic mental disorders. Attenuated psychotic symptoms were subthreshold but associated with distress, risk, and help-seeking. Prodromal psychotic symptoms referred to the prodrome of psychotic disorders. Psychotic symptomatology included delusions and hallucinations within psychotic disorders. Psychotic symptoms was the broadest term, encompassing a range of populations but most commonly involving hallucinations, delusions, thought disorder, and disorganization.

DISCUSSION

A model for conceptualizing the required terms is proposed and future directions needed to advance this field of research are discussed.

School success in childhood and subsequent prodromal symptoms and psychoses in the Northern Finland Birth Cohort 1986

BACKGROUND

Low IQ is a risk factor for psychosis, but the effect of high IQ is more controversial. The aim was to explore the association of childhood school success with prodromal symptoms in adolescence and psychoses in adulthood.

METHODS

In the general population-based Northern Finland Birth Cohort 1986 (n = 8 229), we studied the relationship between teacher-assessed learning deficits, special talents and general school success at age 8 years and both prodromal symptoms (PROD-screen) at age 15-16 years and the occurrence of psychoses by age 30 years.

RESULTS

More prodromal symptoms were experienced by those talented in oral presentation [boys: adjusted odds ratio (OR) 1.49; 95% confidence interval 1.14-1.96; girls: 1.23; 1.00-1.52] or drawing (boys: 1.44; 1.10-1.87). Conversely, being talented in athletics decreased the probability of psychotic-like symptoms (boys: OR 0.72; 0.58-0.90). School success below average predicted less prodromal symptoms with boys (OR 0.68; 0.48-0.97), whereas above-average success predicted more prodromal symptoms with girls (OR 1.22; 1.03-1.44). The occurrence of psychoses was not affected. Learning deficits did not associate with prodromal symptoms or psychoses.

CONCLUSIONS

Learning deficits in childhood did not increase the risk of prodromal symptoms in adolescence or later psychosis in this large birth cohort. Learning deficits are not always associated with increased risk of psychosis, which might be due to, e.g. special support given in schools. The higher prevalence of prodromal symptoms in talented children may reflect a different kind of relationship of school success with prodromal symptoms compared to full psychoses.

Cognitive Deficits in Psychotic Disorders: A Lifespan Perspective

Individuals with disorders that include psychotic symptoms (i.e. psychotic disorders) experience broad cognitive impairments in the chronic state, indicating a dimension of abnormality associated with the experience of psychosis. These impairments negatively impact functional outcome, contributing to the disabling nature of schizophrenia, bipolar disorder, and psychotic depression. The robust and reliable nature of cognitive deficits has led researchers to explore the timing and profile of impairments, as this may elucidate different neurodevelopmental patterns in individuals who experience psychosis. Here, we review the literature on cognitive deficits across the life span of individuals with psychotic disorder and psychotic-like experiences, highlighting the dimensional nature of both psychosis and cognitive ability. We identify premorbid generalized cognitive impairment in schizophrenia that worsens throughout development, and stabilizes by the first-episode of psychosis, suggesting a neurodevelopmental course. Research in affective psychosis is less clear, with mixed evidence regarding premorbid deficits, but a fairly reliable generalized deficit at first-episode, which appears to worsen into the chronic state. In general, cognitive impairments are most severe in schizophrenia, intermediate in bipolar disorder, and the least severe in psychotic depression. In all groups, cognitive deficits are associated with poorer functional outcome. Finally, while the generalized deficit is the clearest and most reliable signal, data suggests specific deficits in verbal memory across all groups, specific processing speed impairments in schizophrenia and executive functioning impairments in bipolar disorder. Cognitive deficits are a core feature of psychotic disorders that provide a window into understanding developmental course and risk for psychosis.

Early motor developmental milestones and schizophrenia: A systematic review and meta-analysis

The neurodevelopmental hypothesis of schizophrenia proposes that impaired brain development is a cause of the illness. Early motor developmental milestones, such as learning to walk, are predictors of later schizophrenia but studies have not been systematically reviewed. The aim of the present systematic review and meta-analysis was to explore the association between early motor developmental milestones and the risk of adult schizophrenia. In addition, we updated a systematic review on motor function and risk of schizophrenia. The PubMed, PsycINFO and Scopus databases were searched for original research articles published up to July 2015. Motor milestones were measured between ages 0 and 13years. Random effect meta-analysis calculated effect estimates (Hedges' g) for the association between individual motor milestones and schizophrenia risk. An electronic database and selected articles reference list search identified 5990 articles after removing duplicates. Sixty-nine full text articles were assessed for eligibility of which six were included in the review. Five studies provided sufficient data for meta-analyses. The following motor milestones were significantly associated with adult schizophrenia risk: walking unsupported (g=0.46; 95% CI 0.27-0.64; p<0.001), standing unsupported (g=0.28; 0.16-0.40; p<0.001) and sitting unsupported (g=0.18; 0.05-0.31; p=0.007). Results for the milestones 'holding head up' and 'grabbing object' were not statistically significant. Delayed walking, sitting and standing unsupported were associated with adult onset schizophrenia. The findings emphasise the importance of timely achievement of these motor milestones in childhood and can contribute to the identification of individuals at risk of psychosis.

Meta-analyses of cognitive and motor function in youth aged 16 years and younger who subsequently develop schizophrenia

BACKGROUND

Previous reviews have reported cognitive and motor deficits in childhood and adolescence among individuals who later develop schizophrenia. However, these reviews focused exclusively on studies of individuals with affected relatives or on population/birth cohorts, incorporated studies with estimated measures of pre-morbid intelligence, or included investigations that examined symptomatic at-risk participants or participants 18 years or older. Thus, it remains unclear whether cognitive and motor deficits constitute robust antecedents of schizophrenia. Meta-analyses were conducted on published studies that examined cognitive or motor function in youth aged 16 years or younger who later developed schizophrenia or a schizophrenia spectrum disorder (SSD) and those who did not.

METHOD

Twenty-three studies fulfilled the following inclusion criteria: (1) written in English; (2) prospective investigations of birth or genetic high-risk cohorts, or follow-back investigations of population samples; (3) objective measures of cognitive or motor performance at age 16 or younger; (4) results provided for individuals who did and who did not develop schizophrenia/SSD later in life; and (5) sufficient data to calculate effect sizes. Four domains of function were examined: IQ; Motor Function; General Academic Achievement; and Mathematics Achievement.

RESULTS

Meta-analyses showed that, by age 16, individuals who subsequently developed schizophrenia/SSD displayed significant deficits in IQ (d=0.51) and motor function (d=0.56), but not in general academic achievement (d=0.25) or mathematics achievement (d=0.21). Subsidiary analysis indicated that the IQ deficit was present by age 13.

CONCLUSIONS

These results demonstrate that deficits in IQ and motor performance precede the prodrome and the onset of illness.

Good school performance is a risk factor of suicide in psychoses: a 35-year follow up of the Northern Finland 1966 Birth Cohort

OBJECTIVE

Our aim was to analyse the relationship between good school performance and risk of suicide in the Northern Finland 1966 Birth Cohort, especially in psychoses.

METHOD

A total of 11,017 cohort members who were alive at the age of 16 years were followed up to the age of 35 years. School performance was measured by the school marks given at age 16 at the end of comprehensive school. School, diagnostic and mortality data were based on national registers.

RESULTS

For psychotic persons having good school performance (highest 20%), the adjusted hazard ratio (HR) for suicide was 3.56 (0.97-13.05) compared with the remaining 80%. In the non-psychotic population (97% without psychiatric hospitalization), accordingly, adjusted HR was 0.28 (0.07-1.16). Interaction (school performance x psychiatric diagnosis) was significant (P = 0.01) even when adjusted with gender, social class and age of onset of illness.

CONCLUSION

Good school performance at age 16 years is associated with increased risk of suicide (before age 35 years) in persons who develop psychosis, whereas in persons who do not develop psychosis, it is associated with lower suicide risk.

The persistence of developmental markers in childhood and adolescence and risk for schizophrenic psychoses in adult life. A 34-year follow-up of the Northern Finland 1966 birth cohort

Childhood precursors of schizophrenia include multiple abnormalities of development. Continuities between early and subsequent deviance are poorly characterised. We studied associations among premorbid developmental deviance using data at ages 1 year (learning to stand, walk, and speak, attainment of bladder and bowel control) and 16 years (success at school). Generalised linear modelling was used to examine differential linear associations and trends across adult psychiatric diagnoses. In babies who, as adults, suffered schizophrenia or any psychosis, those who learned to stand latest were also more likely to perform poorly at school in both motor and theoretical domains at age 16 when compared with earlier learners. The effect was independent of genetic and perinatal factors. We conclude that the early developmental deviation in the first year of life is associated with lower school performance at age 16. Developmental continuity among children who develop psychoses was stronger than among normal controls and those hospitalized for nonpsychotic psychiatric disorder. These findings are in line with the hypothesis that a neural diathesis is present during postnatal brain development before schizophrenia. This supports the longitudinal dimension and life span models of schizophrenia.