Bidirectional link between life events and mood episodes

By Eleanor McDermid, Senior medwireNews Reporter

The link between life events and mood episodes in patients with bipolar disorder is bidirectional, with positive and negative life events having different effects, report researchers.

Life events are a recognised trigger of mood symptoms, but the team says that “clinicians should be aware that life events can also occur as a consequence of mood symptoms.”

The study included 173 outpatients, aged an average of 49.9 years, of whom 121 had bipolar I disorder and 52 had bipolar II disorder or not otherwise specified. During 24 months of follow-up, life events were assessed every 3 months using Paykel’s self-report questionnaire, with about a quarter of the patients reporting positive life events and about 70% negative events.

The number of negative life events patients reported was strongly associated with subsequent increases in both depressive symptoms on the Quick Inventory of Depressive Symptomatology-Self Report (QIDS) and mania symptoms on the Young Mania Rating Scale (YMRS), as well as with increased functional impact on the National Institute of Mental Health Life Chart. These associations persisted after accounting for time, gender, age, level of education, medication use and mood.

Positive life events were significantly associated with later development of mania and functional impairment, but not with depression. There appeared to be a threshold effect, whereby four or more life events led to changes in mood, but fewer did not.

“This study underlines that it is highly important that both positive and negative life events should be clinically evaluated, as they are associated with occurrence of manic and depressed symptoms and functional impairment”, write lead study author Manja Koenders (PsyQ The Hague, the Netherlands) and co-workers in the Journal of Affective Disorders.

They found that the reverse association was also true. Increasing mania symptoms on the YMRS, but not the Life Chart, was associated with a higher number of later positive life events, but did not influence negative events. Conversely, more depressive symptoms on the QIDS, but not the Life Chart, was associated with a higher number of later negative life events.

When looking at the bipolar subtypes separately, the researchers found that life events significantly predicted mood changes in patients with bipolar I disorder, but not in those with bipolar II disorder.

They say that “if these findings hold in replication studies, interventions addressing stress and life events may especially be important to [bipolar I disorder] patients.”

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