[Estradiol inhibits dopamine mediated behavior in rats--an animal model of sex-specific differences in schizophrenia]

Gender, age at onset, and duration of being ill as predictors for the long-term course and outcome of schizophrenia: an international multicenter study

BACKGROUND

The aim of the current study was to explore the effect of gender, age at onset, and duration on the long-term course of schizophrenia.

METHODS

Twenty-nine centers from 25 countries representing all continents participated in the study that included 2358 patients aged 37.21 ± 11.87 years with a DSM-IV or DSM-5 diagnosis of schizophrenia; the Positive and Negative Syndrome Scale as well as relevant clinicodemographic data were gathered. Analysis of variance and analysis of covariance were used, and the methodology corrected for the presence of potentially confounding effects.

RESULTS

There was a 3-year later age at onset for females (P < .001) and lower rates of negative symptoms (P < .01) and higher depression/anxiety measures (P < .05) at some stages. The age at onset manifested a distribution with a single peak for both genders with a tendency of patients with younger onset having slower advancement through illness stages (P = .001). No significant effects were found concerning duration of illness.

DISCUSSION

Our results confirmed a later onset and a possibly more benign course and outcome in females. Age at onset manifested a single peak in both genders, and surprisingly, earlier onset was related to a slower progression of the illness. No effect of duration has been detected. These results are partially in accord with the literature, but they also differ as a consequence of the different starting point of our methodology (a novel staging model), which in our opinion precluded the impact of confounding effects. Future research should focus on the therapeutic policy and implications of these results in more representative samples.

From Onset and Prodromal Stage to a Life-Long Course of Schizophrenia and Its Symptom Dimensions: How Sex, Age, and Other Risk Factors Influence Incidence and Course of Illness

The core symptoms of psychosis-delusions, hallucinations, and thought disorders-are not unique to the disorder traditionally called schizophrenia. They occur at the early stages of various brain diseases, too. Psychosis seems to be a preformed pattern of response of the human brain. Most schizophrenia onsets are marked by a prodromal stage extending over several years and producing the maximum of social consequences. Schizophrenia incidence shows a steep increase culminating at age 15 to 25 years in males. In females it reaches a first peak at age 15 to 30 years and a second, flatter peak at menopausal age (44-49 years). Thereafter, incidence declines to a plateau at later ages. Unlike what the findings of most large-scale epidemiological studies applying an upper age limit of 45 to 55 years suggest, schizophrenia is a disorder of all ages. The lifetime risk seems to be the same for both sexes. The lower incidence in premenopausal women is accounted for by the downregulating effect of oestrogen on dopamine receptors. This hormonal protective effect is antagonised by the genetic effect of a high familial load. In the long-term illness course, right-censored to 11.2 years following first admission, the number of psychotic relapse episodes ranges from 0 to 29 with a mean of 3. The positive symptom dimension produces the highest number of relapses and the shortest duration of exacerbations with a mean length of two months. The depressive and negative symptom dimensions show exacerbations extending over nearly six months on average. Following the first illness episode symptom scores decline sharply, reaching a plateau five years after first admission. Negative symptoms come to a plateau after 2 to 3 years in females and after 5 years in males. Depression is the most frequent type of symptom in the long-term course. In the light of these results urgent treatment issues will be discussed.

The Concept of Schizophrenia: From Unity to Diversity

After over 100 years of research without clarifying the aetiology of schizophrenia, a look at the current state of knowledge in epidemiology, genetics, precursors, psychopathology, and outcome seems worthwhile. The disease concept, created by Kraepelin and modified by Bleuler, has a varied history. Today, schizophrenia is considered a polygenic disorder with onset in early adulthood, characterized by irregular psychotic episodes and functional impairment, but incident cases occur at all ages with marked differences in symptoms and social outcome. Men’s and women’s lifetime risk is nearly the same. At young age, women fall ill a few years later and less severely than men, men more rarely and less severely later in life. The underlying protective effect of oestrogen is antagonized by genetic load. The illness course is heterogeneous and depressive mood the most frequent symptom. Depression and schizophrenia are functionally associated, and affective and nonaffective psychoses do not split neatly. Most social consequences occur at the prodromal stage. Neither schizophrenia as such nor its main symptom dimensions regularly show pronounced deterioration over time. Schizophrenia is neither a residual state of a neurodevelopmental disorder nor a progressing neurodegenerative process. It reflects multifactorial CNS instability, which leads to cognitive deficits and symptom exacerbations.

[Schizophrenia - a disorder in its own right?: results from 25 years of the ABC study]

BACKGROUND

The ABC schizophrenia study conducted by the same team over 25 years initially aimed at illuminating the onset, prodromal stage and sex differences in age at first hospitalization in schizophrenia. New hypotheses were systematically generated from the results achieved.

METHODS

A population-based sample of 276 first admission cases (232 first episodes, age 12-59 years), including a subsample of 130 first admissions (115 first episodes), were assessed to study prodromal stage, first illness episode, medium and long-term course and symptom dimensions in schizophrenia. The samples were compared with age and sex-matched healthy controls and with patients first admitted for unipolar depression. A total of 1,109 consecutive first admissions for schizophrenia spectrum disorders independent from the other study samples were assessed to study changes in symptomatology across the age range.

RESULTS

Before the onset of psychotic symptoms the prodromal stages of schizophrenia and severe and moderately severe depression are difficult to distinguish. The most frequent symptom in the course of schizophrenia, depressed mood, also represents the most frequent initial symptom in both disorders. Prodromal depression is a predictor of more depressive and positive symptoms in the first episode but not in the further course of the illness. Psychosis incidence for men, diagnosed according to ICD 9 (295, 297, 298.3/4), shows a pronounced peak at age 15-24 years, for women a lower peak at age 15-29 years and a second, still lower peak at the menopausal age of 45-49 years. The explanation, confirmed in animal experiments, lies in a protective effect of estrogen due to reduced D2 receptor sensitivity. The effect is antagonized by an elevated genetic risk. Functional and social impairment emerge even at the prodromal stage and the severity depends on sex and social status. Young men with schizophrenia show a less favorable social course because of the earlier age of onset and socially adverse illness behavior. Late onset is associated with a milder, primarily paranoid symptomatology and less severe social impairment. Schizophrenia is a disorder of all ages showing roughly equal life time incidence rates for men and women but considerable difference in certain periods of age. The symptom dimensions show a plateau-like course 2-5 years after the first episode. Hidden behind this picture are irregular symptom exacerbations which vary in duration. Schizophrenia conveys the picture of recurrent vulnerability to crisis and not of a stable residual state of disordered brain development or of a progressive neurodegenerative process.

Monoamines and sexual function in rats bred for increased catatonic reactivity

Body weight, ovary and uterus weight, the nature of estral cycles, and hypothalamus dopamine and noradrenaline levels and plasma testosterone levels were studied in female GC rats, bred for increased catatonic reactivity, at different stages of the estral cycle (estrus, proestrus). The outbred Wistar strain served as controls. On the background of decreased body weight, GC females showed impairments to the morphological cyclical changes in the ovaries and uterus, with a reduction in ovary weight in diestrus (p < 0.01) and a smaller estrogen-dependent increase in uterus weight in estrus as compared with Wistar females. On the background of decreases in dopamine and noradrenaline contents in the hypothalamus, GC rats showed higher levels of these monoamines in estrus and lower levels in diestrus. Plasma testosterone levels in female GC rats were higher in diestrus than in estrus and in Wistar rats.

New developments in the pharmacotherapy of schizophrenia

This review summarizes current key research strategies and the most prominently pursued new potential treatments for schizophrenia. First, new routes of administration for second generation antipsychotics are presented. These include rapidly dissolving tablets, drops and sirups as well as new intramuscular formulations. Newly available short acting and long acting (depot) antipsychotics complement oral antipsychotics so that the full spectrum of routes of administration is now available for second generation antipsychotics. Next to antipsychotic polypharmacy, in which two or more antipsychotics are combined, pharmacological add-on treatments, mainly with benzodiazepines, antidepressants and mood stabilizers enjoy increasing popularity. Most of this practice is driven by personal preferences, clinical experience and marketing rather than evidence based medicine. New pharmacological mechanisms currently utilized in advanced states of development include partial dopamine D2-receptor agonism, supplementation with glutamatergic agents, estrogen and omega-3-fatty acids. While the concept of partial D1-agonism has already led to the successful launch of a new antipsychotic, aripiprazole, the other attempts to improve therapeutic response in schizophrenia patients have so far provided equivocal results. It is argued that they may be helpful for certain subgroups or specific symptoms of schizophrenia patients. In conclusion, many exciting new pharmacological leads are currently pursued and this will very likely augment the options for treating patients with schizophrenia.

Gender differences in schizophrenia

Sex differences in schizophrenia can be caused by the disease process itself, by genetic and hormonal differences, by differences in the maturation and morphology of the brain and in age- and gender-specific behavioural patterns. These hypotheses will be tested on the major results reported in the literature as well as on different levels (epidemiology, risk factors, animal experiments, a controlled clinical study) on data from the ABC Schizophrenia Study. Symptomatology, lifetime risk and symptom-related course of illness-the latter without consideration of age-show no gender differences. However, until menopause illness onset is delayed and severity of illness is reduced by oestrogen on the level of gene expression and transmitter functioning. Oestrogen has an antagonistic effect on the-familial or exogenous-predisposition to illness. As a result, the age distribution of onset and the severity of first-episode illness in young men and post-menopausal women differ from the normal. First intervention trials with oestrogen substitution of neuroleptic therapy have demonstrated antipsychotic effects. The poorer social course of schizophrenia in men than in premenopausal women is accounted for by men's lower level of social development at illness onset and the subsequent impediment of their further development. Men's socially adverse illness behaviour, too, is a contributing factor. Scarcity of the knowledge of differences in the development, morphology and functioning of the male and female brain does not yet allow any definitive conclusions about gender differences in schizophrenia.

Main risk factors for schizophrenia: increased familial loading and pre- and peri-natal complications antagonize the protective effect of oestrogen in women

Women fall ill with schizophrenia 3 to 4 years later than men. The neurobiological mechanism, explaining the delay of onset in women until menopause, is presumably due to a sensitivity reducing effect of oestrogen on central d(2) receptors, as we have previously shown in animal experiments and in a controlled clinical study. The gender difference in age at onset seems to disappear in familial cases with schizophrenia, but it increases to highly significant values of 5 years or more in isolated cases according to a recent study by Albus and Maier (Schizophrenia Research 18:51-57, 1995). We tried to replicate these findings and to test the hypothesis of a functional antagonism between genetic predisposition to illness and the protective effect of oestrogen in a population-based sample of 232 first illness episodes of schizophrenia. In women with at least one first-degree relative suffering from schizophrenia, age at onset defined by first psychotic symptom was significantly reduced by several years and the difference with men disappeared. In sporadic female cases (no mental disorder in first-degree relatives) the age at onset was slightly increased compared with the total sample, which was in accordance with our hypothesis. In men with familial schizophrenia, but without a protective agent like oestrogen, the age at onset was only slightly and non-significantly reduced compared with the total group and with sporadic cases. This was in line with Albus and Maier and with our hypothesis that only the protective effect of oestrogen could be antagonized by a strong genetic disposition. The second main risk factor for schizophrenia is pre- and peri-natal complications. We compared men and women from our sample of first illness episodes with a history of pre- and peri-natal complications with those without a history of obstetric complications. In women the age at first psychotic symptom was markedly reduced, but due to small case numbers not significantly, compared with women without the risk factor and with the total group. Again, schizophrenic men with a history of pre- and peri-natal complications showed only a small, non-significant reduction of age at onset compared with the total and the group without the risk factor. Therefore, we concluded that the degree of genetically determined vulnerability and, presumably to a slightly lesser extent, the degree of pre- and peri-natal brain injury antagonizes the onset delaying effect of oestrogen in schizophrenia.

Depression, negative symptoms, social stagnation and social decline in the early course of schizophrenia

OBJECTIVE

The aim of this study was to investigate when social consequences in schizophrenia emerge, and what conditions give rise to the social disadvantage evident in people suffering from schizophrenia.

METHOD

Early course in schizophrenia was studied in a population-based sample of 232 first illness-episode cases retrospectively from onset to first admission, and in a representative subsample of 115 patients prospectively at six cross-sections over a period of 5 years. Data on non-specific and negative symptomatology and social development was compared with data from an age- and sex-matched control group drawn from the normal population.

RESULTS

In total, 73% of the patients showed a prodromal phase of several years. First signs were depressive and negative symptoms. In 57% of cases social disability emerged 2 to 4 years before first admission. Social consequences depended on the level of social development at onset. An early onset involved social stagnation, and a late onset was associated with social decline. Men's poorer social outcome was determined by their lower level of social development at onset and socially adverse illness behaviour. The 5-year symptom-related course showed no gender difference. At 81% the lifetime prevalence of depressive mood until first admission was several times higher in schizophrenics than in healthy controls. Early depression predicted a lower subsequent score for affective flattening. Suicide indicators were predicted by lack of self-confidence and feelings of guilt early in the illness.

CONCLUSION

Taking into account a prodromal phase of several years on average before first hospital admission, early detection, case identification and intervention are urgently needed. The intervention must be targeted at syndromes such as early depression, negative symptoms and certain forms of cognitive and social impairment.

Epidemiology of schizophrenia

OBJECTIVE

To characterize the epidemiology of schizophrenia.

METHOD

Narrative literature review.

RESULTS

Each year 1 in 10,000 adults (12 to 60 years of age) develops schizophrenia. Based on a restrictive and precise definition of the diagnosis and using standardized assessment methods and large, representative populations, the incidence rates appear stable across countries and cultures and over time, at least for the last 50 years. Schizophrenic patients are not born into ecological and social disadvantage. The uneven distribution of prevalence rates is a result of social selection: an early onset leads to social stagnation, a late onset to descent from a higher social status. The main age range of risk for schizophrenia is 20 to 35 years. It is still unclear whether schizophrenia-like late-onset psychoses (for example, late paraphrenia) after age 60 should be classified as schizophrenia either psychopathologically or etiologically. In 75% of cases, first admission is preceded by a prodromal phase with a mean length of 5 years and a psychotic prephase of one year's duration. On average, women fall ill 3 to 4 years later than men and show a second peak of onset around menopause. Consequently, late-onset schizophrenias are more frequent and more severe in women than in men. The sex difference in age of onset is smaller in cases with a high genetic load and greater in cases with a low genetic load. Type of onset and core symptoms do not differ between the sexes. The most pronounced sex difference is the socially negative illness behaviour of young men.

CONCLUSIONS

Among the factors determining social course and outcome are level of social development at onset, the disorder itself (for example, genetic liability, severity of symptoms, and functional deficits), general biological factors (for example, estrogen), and sex- and age-specific illness behaviour.

Generalized absence epilepsy and catalepsy in rats

Adult WAG/Rij rats are considered adequate genetic models for human generalized absence epilepsy. Rats of this strain of 8, 12, and 18 weeks old and age-matched control Wistar rats were exposed to sound stimulation. After offset of stimulation, all WAG/Rij rats showed cataleptic or even cataplexic reactions, which could persist for up to 20 min. Age effects could be demonstrated. None of the Wistar rats showed cataleptic reactions. Electroencephalographic studies in WAG/Rij rats of 21 weeks showed that spike-wave discharges were abundantly present in the background electroencephalogram prior to sound stimulation. Age-matched Wistar rats had almost no spike-wave discharges. Spike-wave discharges in WAG/Rij rats disappeared during sound stimulation and were then increased compared to the prestimulation and stimulation periods. The electroencephalogram during the cataleptic state was also characterized by the presence of large amplitude 2 Hz waves, interspersed with spike-wave discharges. The data suggest that the cataleptic state can be elicited in genetically epilepsy-prone rats. The youngest WAG/Rij rats showed no spike-wave discharges during the cataleptic state. In all, the data suggest that epilepsy-prone animals are sensitive for catalepsy at an age at which the EEG signs of generalized absence epilepsy are not yet manifest.

Immunological influences in attention-deficit disorder and schizophrenia; is there a link between these two conditions?

This paper aims to explore the influence of the immune system on the pathobiochemistry of movement disorders (Tourette syndrome, obsessive compulsive disorders and attention-deficit disorder, with and without hyperactivity) and schizophrenia. In children, a temporal relationship has been observed between contraction of a group A beta-hemolytic streptococcal infection and subsequent presentation with one of the movement disorders. Pathology investigations reveal that elevated antineuronal antibodies are associated with movement disorders. Similarly, elevations in interleukin-1 beta and interleukin-6 have been reported in schizophrenia. It is now known that the immune system can be activated by conditions other than a viral or bacterial infection, such as: neurological insult, neurotoxicity--endogenous and environmental, neurotransmitter and cholesterol dysregulation. These latter avenues of immune system activation will be explored with respect to schizophrenia.

The estrogen connection: the etiological relationship between diabetes, cancer, rheumatoid arthritis and psychiatric disorders

For some considerable time, there has been a growing awareness that defective essential fatty acid metabolism plays a causal role in the pathogenesis of both schizophrenia and non-insulin-dependent diabetes mellitus (NIDDM) but the influence of defective essential fatty acid metabolism in the pathogenesis of rheumatoid arthritis and cancer is less well appreciated. An EFA deficiency, or defective EFA metabolism, negatively influences prostaglandin synthesis and glucose regulation and transport. Moreover, defective EFA metabolism negatively influences estrogen availability which contributes to the observed gender bias some of these illnesses manifest. While fluctuations of estrogen are known to contribute to the pathogenesis of these conditions, so also do fluctuations of IGF-II and there is some suggestion that IGF-II and insulin may well be inversely regulated. In addition, insulin-dependent diabetes mellitus (IDDM), rheumatoid arthritis, and schizophrenia are thought to be autoimmune disorders, while cancer is associated with immune system failure. Consequently, this paper aims to examine the pathophysiological similarities and differences between mental illness, diabetes, rheumatoid arthritis and cancer in respect of which the causal relationship that obtains between essential fatty acids, estrogen, IGF-II, glucose regulation and autoimmunity will be addressed.