Multi-omics profiling of oral microbial functional signatures and systemic immune-metabolic features in perinatal depression.

Adjustment disorder (AjD) is a maladaptive psychological response to identifiable psychosocial stressors, characterised by distress that exceeds what would normally be expected given the nature of the stressor. In contrast to post-traumatic stress disorder (PTSD), which follows traumatic events of an existential or life-threatening nature, AjD typically develops in response to non-traumatic but challenging life changes such as the death of a loved one, separation or work-related problems (e.g. bullying, work overload, job loss; Karatzias et al., ). Although such events are not unusual in the course of life, they may still lead to clinically significant psychological impairment when coping resources are insufficient. Both major diagnostic classification systems—the International Classification of Diseases (ICD; e.g. World Health Organisation, ) and the Diagnostic and Statistical Manual of Mental Disorders (DSM; e.g. APA, 2013)—include AjD as a distinct mental health diagnosis. Although the diagnostic criteria differ between taxonomies and have been revised over time, they share a common assumption: stressful events can lead to clinically significant psychological distress and functional impairment. AjD differs from other mental health disorders less by its specific symptoms (e.g. distressing thoughts) than by the explicit attribution of symptoms to an identifiable psychosocial stressor. In earlier diagnostic systems, however, AjD was characterised by the absence of disorder-specific symptom criteria, which complicated its differentiation from subsyndromal depressive and anxiety disorders as well as from non-pathological stress reactions. The AjD concept has therefore been criticised for its conceptual vagueness, limited reliability, and restricted discriminant validity (e.g. Baumeister et al., ; Reed et al., ). In response to such criticisms, the ICD-11 introduced a revised definition of AjD that provides a more clearly articulated symptom-based framework by specifying two core symptom clusters: preoccupation with the stressor (i.e. excessive mental preoccupation with the stressor or its consequences) and failure to adapt (e.g. persistent difficulties in recovery, sleep disturbances or concentration problems). Additional accessory symptoms may include avoidance, depressive and anxious symptoms, and impulse control difficulties (World Health Organisation, ). Symptoms must not be better explained by another mental disorder (e.g. a mood disorder, another disorder specifically associated with stress).