A new study says that people who have experienced maltreatment as children are twice as likely to develop both multiple and long-lasting depressive episodes as those without a history of childhood maltreatment.
The research, led by a team at King's College London Institute of Psychiatry also found that maltreated individuals are more likely to respond poorly to pharmacological and psychological treatment for depression.
The results, to be published in the American Journal of Psychiatry
, have emerged from a combined analysis of 16 epidemiological studies involving more than 20,000 participants and of 10 clinical trials involving more than 3,000 participants.
Depression ranks among the most common psychiatric disorders worldwide, with one in ten children exposed to maltreatment including psychological, physical or sexual abuse or neglect. By 2020, depression is predicted to be the second leading contributor to the global burden of disease across all ages, according to the World Health Organisation. The societal impact of depression is largely accounted for by individuals who develop multiple and long-lasting depressive episodes.
Previous research has shown that maltreated individuals are more likely to show abnormalities in biological systems sensitive to psychological stress - such as the brain, the endocrine, and the immune system - both in childhood and in adult life, which could have important clinical implications.
Dr Andrea Danese, senior investigator of the study at King's says: 'Identifying those at risk of multiple and long-lasting depressive episodes is crucial from a public health perspective. The results indicate that childhood maltreatment is associated both with an increased risk of developing recurrent and persistent episodes of depression, and with an increased risk of responding poorly to treatment.
'Therefore prevention and early therapeutic interventions targeting childhood maltreatment could prove vital in helping prevent the major health burden owing to depression. Knowing that individuals with a history of maltreatment won't respond as well to treatment may also be valuable for clinicians in determining patients' prognosis.'
Dr Danese continues: 'The biological abnormalities associated with childhood maltreatment could potentially explain why individuals with a history of maltreatment respond poorly to treatment for depression.'
Individuals with a history of maltreatment are at elevated risk of mental illness throughout their lives. However, in order to understand how early experiences bring about mental illness, future research should explore biological changes associated with maltreatment before accumulation of multiple depressive episodes.
Dr Rudolf Uher, co-author of the paper, says: 'Our study has shown that antidepressant medication, psychological treatment and the combination of the two are less effective in those who have a history of childhood maltreatment. Whilst we still do not know exactly what type of treatment may improve their care, it may be that new treatments based on the biological vulnerabilities associated with childhood maltreatment could prove an exciting avenue for research.'