Testosterone influences well-being, mood and cognition and may play a role in the pathophysiology of bipolar disorder.

To examine testosterone levels in patients with bipolar disorder compared with healthy controls.

We examined baseline total testosterone levels and current depression scores in male and female patients with bipolar disorder and mild to moderate depression and healthy controls.

A significant interaction between diagnosis and gender was observed (F(2,97)=9.791, P=0.002). Testosterone levels were significantly lower for male patients with bipolar disorder compared with male controls (P=0.001). Women with bipolar disorder had significantly higher testosterone levels than female controls (P=0.03).

Disturbances in testosterone levels may represent an important neurobiological abnormality in bipolar disorder and may differ by gender. If these findings are confirmed, the use of gender appropriate treatment strategies for the normalisation of testosterone levels in bipolar disorder depression should be further explored.

Adequate Zn and Mg intakes may be beneficial for the prevention and treatment of mental health problems, such as depression, anxiety and attention-deficit hyperactivity disorder. We aimed to investigate the prospective association between dietary intakes of Zn and Mg and internalising and externalising behaviour problems in a population-based cohort of adolescents.

Prospective analysis (general linear mixed models) of dietary intakes of Zn and Mg assessed using a validated FFQ and mental health symptoms assessed using the Youth Self-Report (YSR), adjusting for sex, physical activity, family income, supplement status, dietary misreporting, BMI, family functioning and energy intake.

Western Australian Pregnancy Cohort (Raine) Study.

Adolescents (n 684) at the 14- and 17-year follow-ups.

Higher dietary intake of Mg (per sd increase) was significantly associated with reduced externalising behaviours (β=−1·45; 95 % CI −2·40, −0·50; P=0·003). There was a trend towards reduced externalising behaviours with higher Zn intake (per sd increase; β=−0·73; 95 % CI −1·57, 0·10; P=0·085).

The study shows an association between higher dietary Mg intake and reduced externalising behaviour problems in adolescents. We observed a similar trend, although not statistically significant, for Zn intake. Randomised controlled trials are necessary to determine any benefit of micronutrient supplementation in the prevention and treatment of mental health problems in adolescents.

To describe the role, contribution and value of research nurses in New Zealand community-based or primary health care research.

Research nurses are increasingly recognised as having a key role in undertaking successful research in hospitals and clinical trial units however only limited work has been undertaken to examine their role in community-based research. Undertaking health research in the community has unique challenges particularly in relation to research design and recruitment and retention of participants.

We describe four community-based research projects involving research nurses, each with particular recruitment, retention and logistical problems. Vignettes are used to illustrate the role, contribution and value of research nurses in a diverse range of community research projects.

The knowledge and skills used by research nurses in these projects included familiarity with communities, cultural competence, health care systems and practice philosophies and in particular with vulnerable populations. Their research actions and activities include competence with a broad range of research methodologies, organisational efficiency, family-centred approach, along with advocacy and flexibility. These are underpinned by nursing knowledge and clinical expertise contributing to an ability to work autonomously. These four projects demonstrate that research nurses in community-based research possess specific attributes which facilitate successful study development, implementation and outcome.

Alzheimer's disease (AD) is considered to be a disorder predominantly affecting memory. It is increasingly recognized that the cognitive profile may be heterogeneous. We hypothesized that it would be possible to define distinct “cognitive phenotypes” in older people with AD.

Participants from three individual studies were included, consisting of 109 patients with a diagnosis of probable AD, and 91 age- and gender-matched control participants. All had demographic and cognitive assessment data available, including the Cambridge Cognitive Examination of the Elderly (CAMCOG). The CAMCOG scores and sub-scores were further analyzed using hierarchical cluster analysis and factor analysis.

Three clusters were identified. The scores loaded onto three factors representing the domains of attention, praxis, calculation, and perception; memory; and language comprehension and executive function. The main difference between the clusters related to degree of memory impairment. The composite score for memory between the clusters remained significantly different despite adjustment for illness duration and age of onset (p < 0.001).

These data suggest clinical heterogeneity within an older group of people with AD. This may have implications for diagnosis, prognosis, response to currently available treatments, and the development of novel therapies.

Abnormal diffusion parameters are reported in specific brain regions and white matter tracts in bipolar disorder.

To investigate whether these abnormalities are generalised, and thus evident in large regions of white matter.

Diffusion parameters were measured at several regions in the corpus callosum and in deep/periventricular white matter in 28 currently euthymic patients with bipolar disorder and controls. White matter hyperintensity loads were assessed.

Comparing the whole data-sets using the sign test, in the group with bipolar disorder, mean diffusivity was greater at all 15 sites (P<0.001) and fractional anisotropy was reduced at 13 (P<0.01). The effect of diagnosis was significant for callosal mean diffusivity and fractional anisotropy and for deep/periventricular mean diffusivity (MANCOVA). Comparing individual regions (Mann–Whitney U-test), prefrontal and periventricular mean diffusivity were significantly increased; callosal and occipital fractional anisotropy were significantly reduced. Former substance use and lithium were possible confounding factors. Periventricular white matter hyperintensities were associated with significantly increased periventricular mean diffusivity in individuals with bipolar disorder.

Generalised white matter microstructural abnormalities may exist in bipolar disorder, possibly exacerbated by past substance use and ameliorated by lithium.