While psychotic episodes are often preceded by depressive symptoms, not all depressive episodes develop into psychosis. For individuals with schizophrenia, a history of depressive symptoms is not uncommon. Research has shown that depression is associated with negative and positive symptoms of psychosis. Additionally, individuals with both schizophrenia and depression are at increased risk for poor mental health outcomes and even suicide. Although there has been evidence demonstrating a higher risk of psychosis in siblings of people with schizophrenia, less is known about depressive symptoms in these siblings. To explore the family risk for psychosis and depressive symptoms, R. Klaassen of Rivierduinen Mental Health in the Netherlands conducted a study involving 822 individuals with schizophrenia, 813 siblings, and 527 participants with no family or personal history of mental illness who served as controls.
Klaassen assessed the lifetime history of depressed mood, episodes of depression, and psychosis in all three groups. The results revealed that the participants with schizophrenia had the highest levels of lifetime depressive episodes and depressed mood, as was expected. The siblings had elevated risk for depressed episodes when compared to control participants. But there was no difference in history or risk of lifetime depressed mood between the controls and siblings. Klaassen also discovered a direct relationship between the frequency/length of depressed symptoms and negative psychotic symptoms, both clinical and subclinical. But only quantity of depressed symptoms was associated with positive psychotic symptoms in siblings and individuals with schizophrenia. And although Klaassen did find a family risk for depressed mood, there was no link discovered for episodes of depression over the lifetime.
Another finding that has clinical relevance is that the clients with schizophrenia and siblings all had increased risk for experiencing episodes of depression. These risks were statistically significant, indicating that family members of people with schizophrenia should be closely monitored for depression. Also, individuals with psychosis should be evaluated for depression as depressive symptoms can exacerbate psychotic symptoms and lead to a worse treatment and health outcome. Klaassen believes that this research expands upon the existing body of evidence showing that depression has a direct effect on the symptoms of psychosis in those with schizophrenia and immediate family members. Klaassen added, “These findings suggest that a co-occurring genetic vulnerability for both depressive and positive and negative psychotic symptomatology exists on a clinical and also on a subclinical level.”
Klaassen, R. M. C., et al. (2013). Depressive symptoms are associated with (sub)clinical psychotic symptoms in patients with non-affective psychotic disorder, siblings and healthy controls. Psychological Medicine 43.4 (2013): 747-56. ProQuest.Web.
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