A study by researchers from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King's College London has shown that mood instability occurs in a wide range of mental disorders and is not exclusive to affective conditions such as depression, bipolar disorder and anxiety disorder.

The research, published in BMJ Open, also found that mood instability was associated with poorer clinical outcomes.

Taken together, these findings suggest that clinicians should screen for mood instability across all common mental health disorders. Targeted interventions for mood instability may also be useful in patients who do not have a formal affective disorder.

This study is the first to use an automated information extraction method to acquire data on mood instability from electronic health records. The sample included almost 28,000 adults who presented to the South London and Maudsley NHS Trust (SLaM) between April 2006 and March 2013 with a psychotic, affective or personality disorder.

The presence of mood instability within one month of presentation was identified using natural language processing (NLP). Outcome measures included the number of days spent in hospital, frequency of hospital admission, compulsory hospital admission and prescription of antipsychotics or non-antipsychotic mood stabilisers over a five year follow-up period.

Mood instability was documented in 12 per cent of people presenting to mental healthcare services. It was most frequently documented in people with bipolar disorder (23 per cent), but was also common in people with personality disorder (18 per cent) and schizophrenia (16 per cent). Mood instability was also associated with a greater number of days spent in hospital, higher frequency of hospitalisation, greater likelihood of compulsory admission and an increased likelihood of prescription of antipsychotics or non-antipsychotic mood stabilisers.

Rashmi Patel, Department of Psychosis Studies at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King's College London, said: 'Mood instability can affect people with a wide range of mental disorders but the symptoms are not always recognised. We have developed an innovative text mining tool to identify the presence of mood instability in almost 28,000 people receiving mental healthcare in South London. We found that mood instability affects people with a wide range of common mental health disorders and is associated with worse clinical outcomes. Our findings highlight the importance of screening for mood instability and the need to develop better strategies to treat these symptoms.'