Achieving symptomatic remission, as defined by the Remission in Schizophrenia Working Group, is intended tobe a meaningful outcome for individuals with schizophrenia, resulting in enhanced well-being. Cross-sectionalstudies have reported an association between symptomatic remission and subjective quality of life (QoL). Longitudinal studies aimed at examining this association have showed mixed results. The aim of this study was toexplore the relationship between symptomatic remission and subjective QoL, both cross-sectionally andlongitudinally. The study comprised data from what were at most 386 patients with schizophrenia, of whom 122–140 werefollowed over a period of four years. Based on cross-sectional remission status and longitudinal remissionpattern, differences in subjective QoL were explored. Remission status was assessed using the Positive andNegative Syndrome Scale (PANSS), and subjective QoL using the Short Form-36 Health Survey (SF-36). Both the cross-sectional and the longitudinal approach showed that patients in symptomatic remission hadsignificantly higher subjective QoL. Patients who were in non-remission at baseline, but who achieved remissionat follow-up, also had significantly higher subjective QoL at follow-up compared with baseline. The results from the study show a clear association between symptomatic remission and subjective QoL. However, achieving symptomatic remission does not appear to be a guarantee of sustained subjective QoL, andonly continued stable remission appears to result in such an outcome.

Objective: The overall aim of this thesis was to investigate the remission criteria according to the Remisson in Schizophrenia Working Group (RWSG), mainly from a longitudinal perspective.

Paper I showed that all remission symptoms in the RSWG criteria, affected the remission status in the cross-sectional setting. In the longitudinal setting, the symptoms Delusions and Hallucinatory behavior contributed mostly to the fluctuation between remission and non-remission, while negative symptoms were more prominent in the group that never reached remission. Finally, the sustainability of remission was significantly longer when only minimal symptom intensity occurred, compared with mild.

Paper II showed that the cognitive areas associated with long-term remission pattern were executive functioning, working memory and verbal functioning, where significant better results were shown in the group of stable remission with only minimal symptoms compared to the group never reaching remission. Verbal functioning was the only cognitive area that could predict long-term remission pattern, as a better result increased the probability of being in long-term remission.

Paper III focused on the patient’s perspective and examined the relationship between subjective quality of life (SQoL) and remission. The paper showed significant associations between a better SQoL, self-assessed with Short Form Health Survey-36, and both cross-sectional remission and long-term. A significant better SQoL was present regardless of being in stable remission over time or if remission was reached during the study period.

Conclusions: The thesis support that the RSWG criteria for remission is a valuable concept, also from a longitudinal perspective. Taken together, the results emphasize the heterogeneity of schizophrenia, where different groups within the disorder show different clinical characteristics. This thesis highlights the importance of regular assessments of broad clinical status, to support a higher frequency and sustainability of remission.

I denna avhandling granskas remissionskriterierna enligt Remission Schizophrenia Working Group (RSWG) för personer med schizofreni ur ett longitudinellt perspektiv.

Studie I visade att alla inkluderade symtom i RSWG-kriterierna bidrog till att avgöra remissionsstatus. Negativa symtom bidrog mest till förekomsten av icke-remission över tid, medan växlingen mellan remission och icke-remission varierade mer med positiva symtom. En ökad hållbarhet i remission förelåg vid en minimal symtomintensitet, jämfört med en mild. 

Studie II visade att patienterna i stabil remission hade bättre kognitiv funktion, jämfört med de som aldrig var i remission. Ju bättre verbal funktion desto högre sannolikhet förelåg dessutom att tillhöra gruppen i stabil remission över tid. 

Studie III visade att den subjektiva livskvaliteten (SQoL) var bättre vid remission jämfört med icke-remission. En bättre SQoL förelåg oavsett om remissionsförekomsten över tid var stabil eller om den uppnåddes under studieperioden, både för den mentala och fysiska hälsan. 

Avhandlingen stöder remissionskriteriernas användbarhet ur ett longitudinellt perspektiv, och återspeglar sjukdomens heterogenitet. Avhandlingen poängterar vikten av att systematiskt följa upp de i avhandlingen undersökta faktorerna för att öka förekomsten samt hållbarheten i symtomatisk remission. 

Purpose Neurocognitive outcomes are frequently used as indicators of real-world functioning in schizophrenia spectrum disorders (SSD). These test results may be influenced by individual differences, such as affective dispositions. Here we investigate the relationship between positive and negative affect and neuropsychological test scores in a large, mixed-gender, population based group of participants without co-morbid substance abuse. Materials and methods We assessed 129 male and female SSD patients with the Positive and Negative Affect Schedule (PANAS) and a comprehensive neuropsychological test battery. Results and conclusions The neuropsychological test scores were mainly predicted by age and gender, with small contributions from negative psychosis symptoms. There was a statistically significant relationship between Positive Affect and processing speed and between Negative Affect and verbal memory and executive function. However, the level of neurocognitive function variance explained by these affects was only 5%. Thus, the neurocognitive test results were not associated with trait affect in any clinically significant manner. This adds to previous findings of no relationship between affective dispositions and psychosis symptom variables in our participants. We suggest that affective traits constitute an independent dimension that may influence well-being, coping, and real-life outcome in SSD patients directly, and not through neurocognitive function.

Cognitive impairment is an established feature of schizophrenia. From a cross-sectional perspective, studies have revealed associations between cognition and remission. Few studies have examined this relationship longitudinally. Here we examine which cognitive domains might be related to long-term remission and symptomatic severity. The present study followed 173 outpatients with schizophrenia for five years, divided into groups based on long-term remission status and symptomatic severity, assessed with the Positive and Negative Syndrome Scale. Cognitive functioning was assessed at baseline, with tests of vigilance, executive functions, processing speed, memory and learning, working memory, and premorbid functioning. Cognitive domains related to long-term remission status were executive functions, working memory, and premorbid functioning. The most prominent cognitive differences were found between the group in stable remission with minimal symptoms, and the non-remission group, the first group demonstrating better cognitive functioning. The study highlights the role of premorbid functioning as a cognitive feature in the prediction of long-term remission. It also indicates the possibility of viewing specific cognitive domains as markers for clinical outcome, highlighting the value of early assessment of cognition. In summary, a certain cognitive profile, in coexistence with long-term non-remission, suggests poorer outcome. Hence, this group is in need of increased support.

A decade has passed since the standardized remission criteria of schizophrenia spectrum disorders-the Andreasen Criteria-were defined. Over 2000 studies have been published, but only a few describe symptomatic remission over time. In this prospective study we followed patients for 3 and 5 years, respectively. The aim was to investigate how different symptoms affect the occurrence of remission and how the remission cut-off level affects remission sustainability. The participants were patients diagnosed with schizophrenia spectrum disorders (DSM-IV). First, the importance of each core symptom for remission was examined using the Positive and Negative Syndrome Scale (n = 274). Second, we investigated which items affect patients to either go in and out of remission or never achieve remission (n = 154). Third, we investigated how the sustainability of remission is affected by a cut-off set to 2 (minimal) and 3 (mild) points, respectively (n = 154). All core symptoms affected the occurence of remission, to a higher or lesser extent. Delusions and Hallucinatory behavior contributed the strongest to fluctuation between remission and non-remission, while the contribution of Mannerism and posturing was very marginal. Negative symptoms were enhanced when remission was never achieved. Moreover, the study found that remission duration was significantly longer for the cut-off score 2 rather than 3. The study shows that, over time, remission criteria discriminate between being stable, unstable, or never in remission. Patients with only a minimal occurrence of symptom intensity exhibit a significantly longer remission duration compared to patients with mild symptom intensity, indicating that the treatment goal should be minimal symptom intensity.