Age at onset and outcome in schizophrenia are related to the degree of familial loading

Familiality in a five-factor model of schizophrenia psychopathology: findings from a 16-month follow-up study

We sought to examine stability associations between family history and variability of schizophrenia symptoms repeatedly examined during a naturalistic follow-up study. The Positive and Negative Syndrome Scale, the Insight and Treatment Attitudes Questionnaire, and the Abnormal Involuntary Movement Scale were administered to 69 patients with familial and 79 patients with sporadic schizophrenia, at hospital admission and at stabilization stage (about 16 months later). Analysis of covariance was applied to identify the association of symptom factors with familiality of schizophrenia. We found that schizophrenia patients with positive family histories had significantly higher dysphoric, activation and negative factors. However, familiality of activation and negative factors were dependent on additional variables such as age of onset (both factors), baseline ratings, insight, and side effects (negative factor). No significant association of family history with intensity of positive and autistic preoccupation factors was found. Familial schizophrenia is characterized by higher severity of dysphoric mood factors that may represent impaired emotional reactivity. It is suggested that dysphoric mood may be a useful phenotype for molecular genetic studies of schizophrenia with positive family history.

Age at onset of schizophrenia: interaction between brain-derived neurotrophic factor and dopamine D3 receptor gene variants

One of the main features of schizophrenia is its age at onset in early adulthood. Dopaminergic dysregulation is the most documented neurobiological factor that may be involved in triggering schizophrenia. Recent findings on neurodevelopmental processes show that the brain-derived neurotrophic factor plays a critical role in the development of mesolimbic dopaminergic-related systems and regulates the expression of dopamine D3 receptors. In this study, we examine whether an interaction between dopamine D3 receptors and brain-derived neurotrophic factor gene variants influences age at onset in patients with schizophrenia. Our findings show that this gene-gene interaction was significantly associated with an earlier emergence of psychosis by 3 years.

Family structure and risk factors for schizophrenia: case-sibling study

BACKGROUND

Several family structure-related factors, such as birth order, family size, parental age, and age differences to siblings, have been suggested as risk factors for schizophrenia. We examined how family-structure-related variables modified the risk of schizophrenia in Finnish families with at least one child with schizophrenia born from 1950 to 1976.

METHODS

We used case-sibling design, a variant of the matched case-control design in the analysis. Patients hospitalized for schizophrenia between 1969 and 1996 were identified from the Finnish Hospital Discharge Register, and their families from the Population Register Center. Only families with at least two children (7914 sibships and 21059 individuals) were included in the analysis. Conditional logistic regression with sex, birth cohort, maternal schizophrenia status, and several family-related variables as explanatory variables was used in the case-sibling design. The effect of variables with the same value in each sibship was analyzed using ordinary logistic regression.

RESULTS

Having a sibling who was less than five years older (OR 1.46, 95% CI 1.29-1.66), or being the firstborn (first born vs. second born 1.62, 1.87-1.4) predicted an elevated risk, but having siblings who were more than ten years older predicted a lower risk (0.66, 0.56-0.79).

CONCLUSIONS

Several family-structure-related variables were identified as risk factors for schizophrenia. The underlying causative mechanisms are likely to be variable.

Age at onset and cognitive functioning in schizophrenia

BACKGROUND

Impairments in cognitive functioning are common in schizophrenia, and the degree of impairment may be associated with the individual's age at onset of the disorder.

AIMS

To examine the effect of age at onset on cognitive functioning using the California Verbal Learning Test, sub-tests from the Wechsler Memory Scale-Revised and sub-scales from the Wechsler Adult Intelligence Scale-Revised among families with schizophrenia.

METHOD

The effect of age at onset on cognitive function in 237 people with schizophrenia from a population-based sample was examined using linear mixed effects models with family as the random effect, and age, gender, chronicity of the illness and number of affected first-degree relatives as fixed effects.

RESULTS

Impairment in verbal learning and memory was associated with earlier disease onset. No association was found for working memory or IQ.

CONCLUSIONS

In patients with early-onset schizophrenia, verbal memory functions in particular should be taken into account in neuropsychological evaluation and efforts at remediation.

Women have later onset than men in schizophrenia--but only in its paranoid form. Results of the DSP project

According to the literature, schizophrenia begins in men earlier than in women. It has been argued that the gender-bound age difference is due to the protective antidopaminergic effect of estrogens in women. However, the effect of gender on the age of onset may vary between different types of schizophrenias, and can also be modulated by marital status and by age at onset of illness. Comprehensive data were collected on 3306 DSM IIR schizophrenia patients, aged 15-64 years, who had been discharged from psychiatric hospitals in Finland in 1982, 1986 and 1990. The age of onset of illness (AOI) was defined by the age at the first admission (AFA). Male patients were admitted earlier than female patients, and a small second peak in women appeared at the age of 40-44. However, there were no gender differences in AFA within diagnostic subgroups, except in paranoid schizophrenia in which AFA was lower in men than in women even when marital status was taken into account. Within paranoid schizophrenia, this effect of gender was significant only in those of the patients whose AFA was higher than 30 years. It is suggested that there is no gender difference in AOI in early onset schizophrenia. In later onset, paranoid schizophrenia, the illness seems to manifest in women later than in men.

Clinical phenotype of schizophrenia in a Finnish isolate

We identified all cases in Finland (population of 5 million) with a diagnosis of schizophrenia born between 1940 and 1969, using four national computerised registers with high reliability. A sample of 397 families was identified in a genetically homogeneous internal isolate (population of 18,000) in northeastern Finland with high prevalence for schizophrenia and an LOD score of 3.8 in chromosome 1. Our aim was to examine with Operational Criteria Checklist for Psychotic Illness (OCCPI) factor analysis the psychotic and affective signs and symptoms of schizophrenia in this genetically homogeneous population, and compare them with findings from individuals with schizophrenia from multiplex families from the whole country. After collecting all original case notes, we made DSM-IV consensus diagnoses and completed OCCPI ratings on a lifetime basis. For the factor analysis, we accepted 190 patients with a diagnosis of schizophrenia. In addition, 466 schizophrenia patients from 147 multiplex families from the whole country were included in the analysis. The OCCPI factor analysis resulted in four factors: "delusions and hallucinations" and "negative" factors, plus two affective ("manic" and "depressive") factors. We compared the pattern of symptoms among three patient groups: isolate patients who were the only affected individuals in their family, isolate patients who had affected family members, and patients from the whole country with affected family members. We found no clear differences among these groups. However, there were significant differences in the frequency of individual OCCPI items between the study groups. Findings in this schizophrenia OCCPI phenotype study suggest that the clinical picture of schizophrenia in a genetically isolated and homogeneous population closely resembles our nationwide findings in Finland.

Psychopathology of early-onset versus late-onset schizophrenia revisited: an observation of 473 neuroleptic-naive patients before and after first-admission treatments

Reports of potential differences in psychopathological presentations between early and late-onset schizophrenia have been controversial. However, such differences in first-episode neuroleptic-naive schizophrenic patients have not been discussed. The authors evaluated symptom profiles in 473 neuroleptic-naive schizophrenic patients before and after first-admission treatments. Both before and after treatment, (1) late-onset schizophrenia had a lower score on affective flattening/social withdrawal than did the earlier-onset counterpart of the illness, even after controlling for potential secondary sources of negative symptoms; (2) systematic persecutory delusion was more severe in patients with late-onset schizophrenia; and (3) the overall effect of age of onset on the psychopathological presentations was greater than the gender-related effects, including the interaction between age of onset and gender. Consideration of late-onset schizophrenia may be important in order to develop an etiologically and clinically reasonable conceptualization of the subtypes of schizophrenia. A factor-analytical study that attempts to compare directly the structure of broad psychopathological presentations in early and late-onset schizophrenia may be a reasonable approach to investigate the longstanding unsolved controversy as to whether or not the neurobiological backgrounds underlying the psychopathological presentations are comparable.

Association study of CAG repeats in the KCNN3 gene in Israeli patients with major psychosis

OBJECTIVES

Several studies reported contradictory findings regarding the association of major psychosis with CAG repeats in the KCNN3 gene. We investigated the contribution of the CAG repeat at the KCNN3 gene, localized to chromosome 1q21.3, to the genetic susceptibility for schizophrenia, schizoaffective and bipolar disorders.

METHODS

Analysis of the number of CAG repeats and the differences in allele length were performed for Israeli Ashkenazi Jews, non-Ashkenazi Jews, and Arabs diagnosed with major psychosis (n=181) versus matched ethnic controls (n=207).

RESULTS

We found no significant difference in the number of CAG repeats between the entire sample of patients and controls. However, an analysis of the differences of allele length revealed a significantly greater number of patients with identical allele length (43.1%) when compared with normal controls (30.4%). Furthermore, an earlier age of non-paranoid schizophrenia onset was found associated with differences in allele sizes. There were no significant differences in the number of CAG repeats and the differences in allele length when subjects were grouped according to gender, ethnic origins of their parents, family history, and diagnostic groups.

CONCLUSIONS

Our results support the hypothesis that a contribution of the KCNN3 gene to genetic susceptibility to major psychosis and their phenotypic polymorphism may be related to the difference of allele length rather than to the number of CAG repeats.

Increasing age does not decrease risk of schizophrenia up to age 40

It is well established that at the population level the age-specific incidence of schizophrenia is highest in the early 20s and decreases with age. We present new findings showing that this is not the case when we assume that only part of the population is susceptible. The study population consisted of birth cohorts born in Finland from 1950 to 1968. These were identified from the Population Register Center, which provided the data as multidimensional tables with sex, and year, month, and place of birth as marginals. Each cohort was followed-up until 1991, up to age 40. Data analyses were based on a compound Poisson statistical model, which assumed that only part of the population is susceptible to develop schizophrenia. The method detects the proportion of susceptibles in population level, but does not identify susceptible individuals. The model was able to reveal the basic hazard distribution, which showed increasing risk of developing schizophrenia with higher age at the individual level among the susceptible part of the population. The increase in risk was more rapid among males, but the susceptible part of the population was of similar size among both sexes. The proportion of susceptibles seemed to be lower in younger cohorts. We conclude that when an individual belongs to the susceptible part of the population, his/her individual risk of developing schizophrenia increases with age, at least up to age 40. This increase is more rapid among males. The reasons behind the lower proportion of susceptibles in younger birth cohorts, as well reasons for differences in risk between sexes remained unclear and need more research.

Age-at-first-registration and heterogeneity in affective psychoses

BACKGROUND

Previous research into age of onset in affective disorders has produced conflicting results. This paper examines the influence of heterogeneity on the age-at-first-registration distribution for the ICD-9 diagnostic group 'affective psychosis'.

METHOD

For 1979-1991, data for age-at-first-registration for 4985 individuals diagnosed with affective psychosis (ICD-9 296.x) were extracted from a name-linked mental health register. These data were divided into (i) '296.1 only', a category used to code unipolar depression (males = 700; females = 1321); and (ii) '296 other', all 296 cases other than 296.1 (males = 1280; females = 1684). Inception rates for each 5-year age division were adjusted for the background population age-structure as a rate per 100,000 population.

RESULTS

The age-at-first-registration distribution for affective psychosis has a wide age range, with women outnumbering men. There is a near-linear increase in inception rates for both men and women with 296.1 only, while the bulk of those with affective psychoses (296 other) have an inverted U-shaped age distribution. Males have an earlier modal age-at-first-registration for 296 other compared to females.

CONCLUSION

The heterogeneity in terms of subtypes and sex in affective psychosis clouds the interpretation of age-at-first-registration. Separating those with unipolar psychotic depression from other subclassifications and differentiating by sex may provide clues to factors that precipitate the onset of affective psychosis.

An association of CAG repeats at the KCNN3 locus with symptom dimensions of schizophrenia

BACKGROUND

In 1999 Cardno et al reported that long CAG repeats in the calcium-activated potassium channel gene hSKCa3/KCNN3 are associated with higher negative symptom dimension scores in schizophrenia patients. There has been no attempt to replicate the results. In this study, we investigated whether a symptom polymorphism of schizophrenia is associated with both the CAG repeat numbers and the difference in allele sizes.

METHODS

We tested the association of CAG repeats with symptom models of schizophrenia in 117 unrelated Jewish patients. A multivariate analysis (MANOVA) of two models of schizophrenia with the repeat distribution and the difference in allele sizes was performed.

RESULTS

We found a significant positive association of the number of CAG repeats with negative syndrome, anergia, activation, and paranoid symptoms. In addition, nonparanoid schizophrenia patients who had differences in allele sizes were characterized by earlier onset of illness.

CONCLUSIONS

The study supports the hypothesis that the combined effect of long CAG repeats and the differences in allele sizes contribute to symptom expression of schizophrenia, particularly on the anergia-activation-paranoid axis.

Recent victimization in women and men with severe mental illness: prevalence and correlates

The problem of violence against individuals with severe mental illness (SMI) has received relatively, little notice, despite several studies suggesting an exceptionally high prevalence of victimization in this population. This paper describes the results of an investigation of the prevalence and correlates of past year physical and sexual assault among a large sample of women and men with SMI drawn from inpatient and outpatient settings across 4 states. Results confirmed preliminary findings of a high prevalence of victimization in this population (with sexual abuse more prevalent for women and physical abuse more prevalent for men), and indicated the existence of a range of correlates of recent victimization, including demographic factors and living circumstances, history of childhood abuse, and psychiatric illness severity and substance abuse. The research and clinical implications of these findings are discussed.

A genomewide linkage study of age at onset in schizophrenia

There is strong evidence for a genetic contribution to age at onset of schizophrenia, which probably involves both susceptibility loci for schizophrenia and modifying loci acting independent of disease risk. We sought evidence of linkage to loci that influence age at onset of schizophrenia in a sample of 94 affected sibling pairs with DSM-IV schizophrenia or schizoaffective disorder, and age at first psychiatric contact of 45 years or less. Individuals were genotyped for 229 microsatellite markers spaced at approximately 20 cM intervals throughout the genome. Loci contributing to age at onset were sought by a quantitative maximum-likelihood multipoint linkage analysis using MAPMAKER/SIBS. A nonparametric multipoint analysis was also performed. The genomewide significance of linkage results was assessed by simulation studies. There were six maximum-likelihood LOD score peaks of 1.5 or greater, the highest being on chromosome 17q (LOD = 2.54; genomewide P = 0.27). This fulfils Lander and Kruglyak's [1995: Nat Genet 11:241-247] criteria for suggestive linkage in that it would be expected to occur once or less (0.3 times) per genome scan. However, this finding should be treated with caution because the LOD score appeared to be almost solely accounted for by the pattern of ibd sharing at one marker (D17S787), with virtually no evidence of linkage over flanking markers. None of the linkage results achieved genomewide statistical significance, but the LOD score peak on chromosome 13q (LOD = 1.68) coincided with the region showing maximum evidence for linkage in the study by Blouin et al. [1998: Nat Genet 20:70-73] of categorical schizophrenia.

Accuracy of register- and record-based bipolar I disorder diagnoses in Finland; a study of twins

Registers have been widely used in schizophrenia studies. For bipolar disorder, the use has been more limited and no studies exist concerning accuracy of bipolar I diagnoses in registers. We have collected an unselected twin sample for a study of bipolar I disorder. We report here the diagnostic procedures and accuracy of bipolar I diagnoses in a nation-wide hospital discharge registry. We evaluated also the accuracy of the medical record-based best-estimate diagnoses, comparing these with the SCID interview diagnoses. From the National Hospital Discharge Register we identified all like-sex twins, born 1940-1957, (N=42), and all like- or opposite-sex twins, born 1961-1969, (N=15), who had at least once a diagnosis of bipolar I disorder. The best-estimate diagnoses based on medical records, and were made by two doctors blind to each other, and according to DSM-IV-criteria. Diag-noses were then confirmed by SCID interviews, with the mi-nimum follow-up time after the first admission being 6 years. The accuracy of bipolar diagnoses in the register was 92% and 87%, accordingly. When comparing the best-estimate diagnoses to SCID interview diagnoses, there was one false positive case in the first sample, 3.4% [95% CI 0.1% to 7.8%], and none in the second sample. Our study shows that a diagnosis of bipolar I disorder in the hospital discharge register, or if based only on medical records, is highly reliable and stable. These results strengthen the usefulness of regis-ters also in bipolar disorder.

[Lack of gender effect on familial schizophrenia. A Brazilian study]

Epidemiological studies on schizophrenia have showed different age at onset between gender, in which male schizophrenics present symptoms earlier than females. However this gender effect is not observed within familial schizophrenia. The present study investigates the age at onset in 31 RDC-schizophrenics from 13 Brazilian families. No differences in age at onset were found between gender, confirming previous studies in other populations. This result may indicate genetic influences on age at onset in a subgroup of patients affected by schizophrenia and can be explored by molecular genetic studies.

Childhood-onset schizophrenia: rare but worth studying

Childhood-onset schizophrenia (defined by an onset of psychosis by age 12) is a rare and severe form of the disorder that is clinically and neurobiologically continuous with the adult-onset disorder. There is growing evidence for more salient risk or etiologic factors, particularly familial, in this possibly more homogeneous patient population. For the 49 patients with very early onset schizophrenia studied to date at the National Institute of Mental Health, there were more severe premorbid neuro-developmental abnormalities, a higher rate of cytogenetic anomalies, and a seemingly higher rate of familial schizophrenia and spectrum disorders than later onset cases. There was no evidence for increased obstetric complications or environmental stress. These data, while preliminary, suggest that a very early age of onset of schizophrenia may be secondary to greater familial vulnerability. Consequently, genetic studies of these patients may be particularly informative and may provide important etiologic information.