The ‘ethnic density hypothesis' is a proposition that members of ethnic minority groups may have better mental health when they live in areas with higher proportions of people of the same ethnicity. Investigations into this hypothesis have resulted in a complex and sometimes disparate literature.

To systematically identify relevant studies, summarise their findings and discuss potential explanations of the associations found between ethnic density and mental disorders.

A narrative review of studies published up to January 2011, identified through a systematic search strategy. Studies included have a defined ethnic minority sample; some measure of ethnic density defined at a geographical scale smaller than a nation or a US state; and a measure ascertaining mental health or disorder.

A total of 34 papers from 29 data-sets were identified. Protective associations between ethnic density and diagnosis of mental disorders were most consistent in older US ecological studies of admission rates. Among more recent multilevel studies, there was some evidence of ethnic density being protective against depression and anxiety for African American people and Hispanic adults in the USA. However, Hispanic, Asian–American and Canadian ‘visible minority’ adolescents have higher levels of depression at higher ethnic densities. Studies in the UK showed mixed results, with evidence for protective associations most consistent for psychoses.

The most consistent associations with ethnic density are found for psychoses. Ethnic density may also protect against other mental disorders, but presently, as most studies of ethnic density have limited statistical power, and given the heterogeneity of their study designs, our conclusions can only be tentative.

Attention-deficit hyperactivity disorder (ADHD) has been associated with socioeconomic difficulties later in life. Little research in this area has been based on longitudinal and community studies.

To examine the relationship between childhood attention problems and socioeconomic status 18 years later.

Using a French community sample of 1103 youths followed from 1991 to 2009, we tested associations between childhood attention problems and socioeconomic status between ages 22 and 35 years, adjusting for potential childhood and family confounders.

Individuals with high levels of childhood attention problems were three times more likely to experience subsequent socioeconomic disadvantage than those with low levels of attention problems (odds ratio 3.44, 95% CI 1.72–6.92). This association remained statistically significant even after adjusting for childhood externalising problems, low family income, parental divorce and parental alcohol problems.

This longitudinal community-based study shows an association between childhood attention problems and socioeconomic disadvantage in adulthood. Taking into account ADHD and associated difficulties could help reduce the long-term socioeconomic burden of the disorder.

Epidemiological research has shown that hallucinations and delusions, the classic symptoms of psychosis, are far more prevalent in the population than actual psychotic disorder. These symptoms are especially prevalent in childhood and adolescence. Longitudinal research has demonstrated that psychotic symptoms in adolescence increase the risk of psychotic disorder in adulthood. There has been a lack of research, however, on the immediate clinicopathological significance of psychotic symptoms in adolescence.

To investigate the relationship between psychotic symptoms and non-psychotic psychopathology in community samples of adolescents in terms of prevalence, co-occurring disorders, comorbid (multiple) psychopathology and variation across early v. middle adolescence.

Data from four population studies were used: two early adolescence studies (ages 11–13 years) and two mid-adolescence studies (ages 13–16 years). Studies 1 and 2 involved school-based surveys of 2243 children aged 11–16 years for psychotic symptoms and for emotional and behavioural symptoms of psychopathology. Studies 3 and 4 involved in-depth diagnostic interview assessments of psychotic symptoms and lifetime psychiatric disorders in community samples of 423 children aged 11–15 years.

Younger adolescents had a higher prevalence (21–23%) of psychotic symptoms than older adolescents (7%). In both age groups the majority of adolescents who reported psychotic symptoms had at least one diagnosable non-psychotic psychiatric disorder, although associations with psychopathology increased with age: nearly 80% of the mid-adolescence sample who reported psychotic symptoms had at least one diagnosis, compared with 57% of the early adolescence sample. Adolescents who reported psychotic symptoms were at particularly high risk of having multiple co-occurring diagnoses.

Psychotic symptoms are important risk markers for a wide range of non-psychotic psychopathological disorders, in particular for severe psychopathology characterised by multiple co-occurring diagnoses. These symptoms should be carefully assessed in all patients.

White matter abnormalities have been implicated in the aetiology of major depressive disorder; however, the relationship between the severity of symptoms and white matter integrity is currently unclear.

To investigate white matter integrity in people with major depression and healthy controls, and to assess its relationship with depressive symptom severity.

Diffusion tensor imaging data were acquired from 66 patients with recurrent major depression and a control group of 66 healthy individuals matched for age, gender and IQ score, and analysed with tract-based spatial statistics. The relationship between white matter integrity and severity of depression as measured by the Beck Depression Inventory was examined.

Depressive illness was associated with widespread regions of decreased white matter integrity, including regions in the corpus callosum, superior longitudinal fasciculus and anterior corona radiata, compared with the control group. Increasing symptom severity was negatively correlated with white matter integrity, predominantly in the corpus callosum.

Widespread alterations in white matter integrity are evident in major depressive disorder. These abnormalities are heightened with increasing severity of depressive symptoms.

Brain white matter changes (WMC) and depressive symptoms are linked, but the directionality of this association remains unclear.

To investigate the relationship between baseline and incident depression and progression of white matter changes.

In a longitudinal multicentre pan-European study (Leukoaraiosis and Disability in the elderly, LADIS), participants aged over 64 underwent baseline magnetic resonance imaging (MRI) and clinical assessments. Repeat scans were obtained at 3 years. Depressive outcomes were assessed in terms of depressive episodes and the Geriatric Depression Scale (GDS). Progression of WMC was measured using the modified Rotterdam Progression scale.

Progression of WMC was significantly associated with incident depression during year 3 of the study (P = 0.002) and remained significant after controlling for transition to disability, baseline WMC and baseline history of depression. There was no significant association between progression of WMC and GDS score, and no significant relationship between progression of WMC and history of depression at baseline.

Our results support the vascular depression hypothesis and implicate WMC as causal in the pathogenesis of late-life depression.

Late-life depression is a common and heterogeneous illness, associated with structural abnormalities in both grey and white matter.

To examine the relationship between age at onset and magnetic resonance imaging (MRI) measures of grey and white matter to establish whether they support particular hypotheses regarding the anatomy and aetiology of network disruption in late-life depression.

We studied 36 participants with late-life depression. Grey matter was examined using T 1-weighted MRI and analysed using voxel-based morphometry. The hippocampus was automatically segmented and volume and shape analysis performed. White matter was examined using diffusion tensor imaging and analysed using tract-based spatial statistics.

Later age at onset was significantly associated with reduced fractional anisotropy of widespread tracts, in particular the anterior thalamic radiation and superior longitudinal fasciculus. Earlier age at onset was associated with reduced hippocampal volume normalised to whole brain size bilaterally. However, no significant correlations were detected using hippocampal shape analysis or voxel-based morphometry.

Overall, the results were compatible with the vascular hypothesis, and provided some support for the glucocorticoid cascade hypothesis.

Reports of neuroleptic malignant syndrome (NMS) induced by second-generation antipsychotic drugs highlight a propensity for atypical clinical presentations.

To systematically compare the clinical profile of NMS induced by first- (1G-NMS) and second-generation antipsychotic drugs (2G-NMS).

The Australian Adverse Drug Reaction Advisory Committee (ADRAC) database was searched to identify individuals with NMS reported between April 1994 and September 2010. The clinical characteristics of 208 people with NMS induced by monotherapy with first- or second-generation antipsychotic drugs, as well as presenting features of NMS, were compared.

The individuals with 2G-NMS were younger and more likely to have a psychotic disorder diagnosis. The features of NMS in the two groups were very similar, except that people with 2G-NMS were less likely to present with rigidity or extrapyramidal signs compared with those with 1G-NMS. This difference was due to the lower rates of rigidity in those with clozapine-induced NMS. Mortality was considerably lower for those with 2G-NMS (3.0%) compared with 1G-NMS (16.3%), and the former were more likely to have received supportive treatment.

The clinical profile of 2G-NMS is largely similar to 1G-NMS, with clozapine-induced NMS being differentiated by the relative lack of rigidity as a feature. Mortality is lower for 2G-NMS.

Direct social contact interventions are known to reduce mental health stigma. Filmed social contact may be equally effective and have practical and cost advantages.

To compare the effectiveness of a DVD, a live intervention and a lecture control, in reducing stigma, testing the hypotheses that: (a) DVD and live interventions will be equally effective; and (b) the interventions with social contact (DVD/live) will be more effective than the lecture. Cost-effectiveness, process and acceptability are also assessed.

Student nurses were randomised to: (a) watch a DVD of service users/informal carers talking about their experiences, (b) watch a similar live presentation, or (c) attend a lecture. Primary outcomes were changes in attitudes (using the Mental Illness: Clinicians Attitudes Scale, MICA), emotional reactions (using the Emotional Reactions to Mental Illness Scale, ERMIS), intended proximity (using the Reported and Intended Behaviour Scale, RIBS), and knowledge (using the Social Contact Intended Learning Outcomes, SCILO), immediately after the intervention and at 4-month follow-up.

For the 216 participants, there were no differences between the DVD and live groups on MICA, ERMIS or RIBS scores. The DVD group had higher SCILO (knowledge) scores. The combined social contact group (DVD/live) had better MICA and RIBS scores than the lecture group, the latter difference maintained at 4 months. The DVD was the most cost-effective of the interventions, and the live session the most popular.

Our hypotheses were confirmed. This study supports the wider use of filmed social contact interventions to reduce stigma about mental illness.

The Mental Health Recovery Star (MHRS) is a popular outcome measure rated collaboratively by staff and service users, but its psychometric properties are unknown.

To assess the MHRS's acceptability, reliability and convergent validity.

A total of 172 services users and 120 staff from in-patient and community services participated. Interrater reliability of staff-only ratings and test–retest reliability of staff-only and collaborative ratings were assessed using intraclass correlation coefficients (ICCs). Convergent validity between MHRS ratings and standardised measures of social functioning and recovery was assessed using Pearson correlation. The influence of collaboration on ratings was assessed using descriptive statistics and ICCs.

The MHRS was relatively quick and easy to use and had good test–retest reliability, but interrater reliability was inadequate. Collaborative ratings were slightly higher than staff-only ratings. Convergent validity suggests it assesses social function more than recovery.

The MHRS cannot be recommended as a routine clinical outcome tool but may facilitate collaborative care planning.