Association of premorbid intelligence with level of functioning and illness severity in bipolar disorder

BACKGROUND

Bipolar disorder is a severe psychiatric syndrome defined by periodic mood shifts. Patients with bipolar disorder show cognitive impairments relative to healthy controls. The risk of developing schizophrenia, and partially also bipolar disorder, has previously been shown to increase with lower premorbid intelligence. It is not known if premorbid intelligence is associated with level of functioning and illness severity of people having developed bipolar disorder.

METHODS

We used multiple linear and ordinal regression to analyze how premorbid intelligence, as measured at conscription, associate with functional outcome and illness severity in Swedish male bipolar disorder patients (n = 788).

RESULTS

We found that lower premorbid intelligence is associated with lower percentage of time in work, after adjusting for age and bipolar subtype, and correcting for multiple comparisons. We also found a strong negative association with the total number of inpatient episodes and psychiatric comorbidity, but not with interepisodic remission, treatment with psychotherapy or lithium or the presence of any complicating socioeconomical factors. Adjusting for confounding genetic factors using polygenic risk scores for bipolar disorder and schizophrenia had no effect on the associations.

LIMITATIONS

This study lacks females and controls and may thus have lower generalizability.

CONCLUSION

In conclusion, premorbid intelligence is associated with both level of functioning and illness severity as well as comorbidity in bipolar disorder patients. Further research is needed to develop targeted interventions for this subgroup of bipolar disorder patients.

Differences in psychosocial functioning between psychotic disorders in the Finnish SUPER study

BACKGROUND

Psychotic disorders differ in their impact on psychosocial functioning. However, few studies have directly compared psychosocial functioning and its determinants between schizophrenia, schizoaffective disorder (SAD), bipolar disorder (BD), and major depressive disorder with psychotic features (psychotic MDD).

OBJECTIVE

We compared rates of independent living, employment, marriage, and having children between these diagnostic groups in a large national sample of participants with psychotic disorders in Finland.

METHODS

A cross-sectional substudy of participants (N = 9148) aged 18 to 65 years in the Finnish SUPER study, recruited nationwide from health- and social care settings and with advertisements. Psychosis diagnoses, age of onset, and hospitalizations were collected from healthcare registers. Participants were interviewed for psychosocial functioning. Associations of age of onset, hospitalizations, gender, and education with psychosocial functioning were analyzed using logistic regression models.

RESULTS

Of participants, 13.8% were employed or studying, 72.0% living independently and 32.5% had children. Overall, BD was associated with best, SAD and psychotic MDD with intermediate, and schizophrenia with worst level of psychosocial functioning. Greatest differences were found in independent living (OR 4.06 for BD vs. schizophrenia). In multivariate models, gender and number of hospitalizations predicted employment, marriage, and independent living in all diagnostic categories, and age of onset in some diagnostic categories.

CONCLUSIONS

Level of functioning and psychosocial outcomes differed markedly between psychotic disorders, particularly in independent living. Outcomes were worst for schizophrenia and best for BD. Across all psychotic disorders, female gender and lifetime number of hospitalizations had strong independent associations with marriage, employment, and independent living.