Highlights of this issue

Impact of cannabis on risk of psychosis and suicide

Two papers in the Journal this week focus on the potential impact of cannabis use on mental health outcomes. Di Forti et al (pp. ) examined the risk of psychosis associated with use of high-potency cannabis. They found that individuals presenting with a first episode of psychosis were no more likely than local population controls to have ever taken cannabis but the former were more likely to have taken high-potency cannabis. Price et al (pp. ) utilised data from a longitudinal study of men conscripted for military service in Sweden and found that although cannabis use was associated with an elevated risk of suicide, adjustment for markers of psychological and behavioural problems eliminated the association.

Stress sensitivity and job burnout

Daily-life stress sensitivity was found to be associated with depressive symptoms and major depressive disorder in women participating in a longitudinal twin study described by Wichers et al (pp. ). The effect was strongest among those with high genetic liability and without exposure to negative life events. In a survey of community mental health staff working in the Veneto region of Italy, Lasalvia et al (pp. ) found that nearly two-thirds of psychiatric staff reported high levels of job distress. Burnout, suffered by one in five staff members, was predicted by higher frequency of face-to-face interaction with service users, length of tenure, weakness of work group cohesion, and perceived unfairness.

Depression in Sri Lanka and Latin America

In the first large population-based twin study of depression conducted in a low-income country (Sri Lanka), Ball et al (pp. ) found that the strength of genetic influence on depression in women was similar to that obtained from samples in higher-income countries. For men the results were less clear but the authors found some evidence to suggest that environmental influences might be greater. In a population-based study of people aged over 65 years set in Peru, Mexico and Venezuela, Guerra et al (pp. ) found that the prevalence of late-life depression was similar to that seen in Europe, with little variation seen between study centres. Most individuals with depression had never received any treatment.

Occurrence of depression – population prevalence and primary care incidence

Inspired by the epidemiologist Rose and his emphasis on understanding determinants of ‘sick populations’ not just ‘sick individuals’, Veerman et al (pp. ) used population data to develop and test models for predicting prevalence of depression. They found that mean Beck Depression Inventory score predicted the prevalence of depression and concluded that depression rates depend on the characteristics of both individuals and populations. Using data from 298 UK general practices, Rait et al (pp. ) found that the incidence of GP-recorded depression fell between 1996 and 2006 while the incidence of depressive symptom recording rose. Depression and depressive symptoms were both more commonly recorded for women and in more deprived areas.

Cognitive functioning and quality of vascular care for those with psychosis

In a meta-analytic study of cognitive functioning, Bora et al (pp. ) found that differences in cognitive performance between individuals with schizophrenia, schizoaffective disorder and affective psychoses were small and largely driven by a subgroup of individuals with schizophrenia who were more likely to be male, have severe negative symptoms and younger age at onset. In a universal healthcare setting, Kisely et al (pp. ) found that individuals with psychosis received poorer levels of vascular care. Despite higher mortality rates, they were less likely to receive guideline-consistent treatment for both ischaemic heart disease events and stroke.

Typology of bipolar 1 episodes and the link between autism and intellectual disability

In a prospective study of individuals with bipolar 1 disorder followed for up to 25 years for the occurrence of mood episodes, Solomon et al (pp. ) found that almost one-third of episodes could be classified as major depression, one-fifth as mania and one-quarter as cycling. The authors call for a revision of diagnostic classification systems to add a category for cycling episodes given their frequency. In a population-based twin study, Hoekstra et al (pp. ) found a modest association between extreme autistic traits and intellectual disability, underpinned by only a modest genetic correlation. The authors conclude that extreme autistic traits are substantially genetically independent of the vulnerability to impaired intellectual functioning.