Risk factors for psychotic major depression

Risk factors are attributes, characteristics, or experience that increase the likelihood of developing an illness or disorder. An understanding of the risk factors involved in mental disorders may inform the development of more effective treatments or even lead to prevention. Particular attention is currently being paid to risk factors in psychoses –  a group of disorders that cause people to perceive or interpret things differently from those around them. Psychosis is typically characterised by hallucinations (seeing or hearing things that are not there) and delusions (holding beliefs that, when examined, are obviously not true). One type of psychosis, Psychotic Major Depression (PMD), is particularly under researched. PMD is a depressive disorder (characterised by low mood and/or decreased interest or pleasure) with the addition of hallucinations and/or delusions.

To investigate risk factors in people with PMD, we examined a group of people who had come into contact with mental health services for the first time and had a diagnosis of PMD. Data was collected on a number of social and biological risk factors including social isolation, childhood adversity (abuse, neglect), traumatic life events, minor physical anomalies (indicators of altered growth during the early parts of pre-birth development and thought to be signs of developmental problems), neurological soft signs (irregular performance on physical tests of the nervous system which is similarly thought to indicate developmental problem) and family history of psychosis or any mental illness (used as an indicator of genetic risk).

We compared the PMD group to a group of people with no psychosis. Further, we also collected data from people with schizophrenia and a group with psychotic bipolar disorder (two other types of psychosis) as comparison groups. Further, we also recontacted these people, 10 years after their first contact with mental health services so we could check whether our initial diagnoses were correct (as diagnoses can change over time as more information becomes available).

Many social and biological risk factors were associated with both PMD and schizophrenia including living alone, basic level qualifications, being unemployed, having contact with friends less than monthly, having no close confidants, having experienced childhood adversity, having a family history of mental illness, having a family history of psychosis and having more neurological soft signs. Few risk factors that were associated with PMD were also associated with a diagnosis of bipolar disorder. When we accounted for change in diagnosis, there were some important differences in the results. The results led us to conclude that factors that increase risk for PMD may be more similar to schizophrenia than previously recognised. Future work on risk factors in PMD should try to examine what the differences are between PMD and other psychoses to help us understand why people develop the different disorders, which may help us target more effective treatments, and maybe even prevention plans. We also concluded that the change in diagnosis is important for unpicking the ‘true’ picture of risk and should be accounted for in any future research.

 

Publication

Biological and psychosocial risk factors for psychotic major depression.
Heslin M, Desai R, Lappin JM, Donoghue K, Lomas B, Reininghaus U, Onyejiaka A, Croudace T, Jones P, Murray RM, Fearon P, Doody GA, Dazzan P, Fisher HL, Demjaha A, Craig T, Morgan C.
Soc Psychiatry Psychiatr Epidemiol. 2015 Oct 31

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