According to recent findings published in The Psychiatric Quarterly, the researchers affiliated with Poznan University of Medical Sciences in Poland, and Campbell Family Mental Health Research Institute in Canada identified clinical and demographic characteristics that can predict symptoms related to both schizophrenia and bipolar affective disorder.
The neurobiologic and behavioral basis of neuropsychiatric illness, including both schizophrenia and bipolar affective disorder, is characterized by the complex interplay between genetic and environmental variables. These two disorders are characterized by significant genetic overlap (the genetic correlation coefficient is 0.6), as well as significant clinical presentation overlap.
Patients diagnosed with schizophrenia often present with a combination of positive (hallucinations, delusions), negative (apathy, low motivation), and cognitive (impaired learning, memory, attention, executive function) symptoms.
Bipolar affective disorder, on the other hand, is a severe mood disorder that is difficult to diagnose, and is frequently underdiagnosed. The prevalence of bipolar type I and type II in the general population is approximately 1%, but this estimate is likely too low.
In the current study, investigators examined whether clinical and demographic characteristics (eg, age at onset, duration of illness, sex) of the sample (443 patients with bipolar disorder, and 439 patients with schizophrenia) can serve as predictors of “symptom dimensions occurrence” in these patients.
In their sample, the average age at onset of bipolar disorder was 30.62 (SD=11.17) and schizophrenia 23.4 (SD=6.59). Patients diagnosed with schizophrenia presented with a longer duration of illness (22.25; SD=21).
Results indicate that male gender and later age at onset appear protective towards higher depression scores in patients diagnosed with either schizophrenia or bipolar disorder; this finding is consistent with previous reports showing that females are significantly more likely to experience depressive symptoms compared with males. In the present study, “later age at onset” was operationalized as “adult onset.”
For individuals diagnosed with bipolar disorder or schizophrenia, marital status “single”, as well as the presence of family history of psychiatric disorders or premorbid personality disorders, appears to be a significant predictor of depressive symptoms.
For individuals diagnosed with schizophrenia, age at onset appears to be a significant predictor for depression, with later age at onset being protective. Also, the presence of premorbid personality disorders, concomitant with a definite psychological stressor, appears to be a significant risk factor for suicidal behavioral disturbances. As noted by authors, between 4% and 10% of deaths among patients diagnosed with schizophrenia is due to suicide, which is associated with the severity of depressive symptoms.
Maciukiewicz M, Pawlak J, Kapelski P, et al. Can psychological, social and demographical factors predict clinical characteristics symptomatology of bipolar affective disorder and schizophrenia? Psychiatr Q. 2016;87:501-513.