A few studies have examined the association between vitamin D and telomere length, and fewer still have examined the relationship in black or male populations. We investigated the cross-sectional association between the vitamin D metabolite 25-hydroxyvitamin D (25(OH)D) concentration in plasma and relative leucocyte telomere length (LTL) in 1154 US radiologic technologists who were 48–93 years old (373 white females, 278 white males, 338 black females, 165 black males). Plasma 25(OH)D concentration was measured by the chemiluminescence immunoassay, and relative LTL was measured by quantitative PCR. Logistic regression was used to obtain OR and 95 % CI for long v. short (based on median) LTL in relation to continuous 25(OH)D, quartiles of 25(OH)D and 25(OH)D deficiency. We found no significant association between continuous 25(OH)D and long LTL in all participants (Ptrend=0·440), nor in white females (Ptrend=0·845), white males (Ptrend=0·636), black females (Ptrend=0·967) or black males (Ptrend=0·484). Vitamin D deficiency (defined as 25(OH)D<30 nmol/l), however, was significantly associated with short LTL in whites (P=0·024), but not in other groups. In this population, we found little evidence to support associations between 25(OH)D and long LTL over the entire range of 25(OH)D in the overall study population or by sex and race.

Background: Exposure-based therapy for anxiety disorders is believed to operate on the basis of fear extinction. Studies have shown acute administration of D-cycloserine (DCS) enhances fear extinction in animals and facilitates exposure therapy in humans, but the neural mechanisms are not completely understood. To date, no study has examined neural effects of acute DCS in anxiety-disordered populations.

Methods: Two hours prior to functional magnetic resonance imaging scanning, 23 spider-phobic and 23 non-phobic participants were randomized to receive DCS 100 mg or placebo. During scanning, participants viewed spider, butterfly, and Gaussian-blurred baseline images in a block-design paradigm. Diagnostic and treatment groups were compared regarding differential activations to spider versus butterfly stimuli.

Results: In the phobic group, DCS enhanced prefrontal (PFC), dorsal anterior cingulate (ACC), and insula activations. For controls, DCS enhanced ventral ACC and caudate activations. There was a positive correlation between lateral PFC and amygdala activation for the placebo-phobic group. Reported distress during symptom provocation was correlated with amygdala activation in the placebo-phobic group and orbitofrontal cortex activation in the DCS-phobic group.

Conclusions: Results suggest that during initial phobic symptom provocation DCS enhances activation in regions involved in cognitive control and interoceptive integration, including the PFC, ACC, and insular cortices for phobic participants.

In the context of evidence-based clinical practice (EBCP), the reliability of empirical data is largely determined by the methodological quality of research design. PsycBITE™ (Psychological Database of Brain Impairment Treatment Efficacy) is a web-based database listing all published, empirical reports on the effectiveness of nonpharmacological interventions for the psychological consequences of acquired brain impairment (ABI). The aim of this study was to survey the listings of PsycBITE™ and examine the methodological quality of the reports it contains. Reports listed in PsycBITE™ include systematic reviews (SRs), randomised controlled trials (RCTs), non-RCTs, case series (CSs) and single-subject designs (SSDs). They are indexed according to research design, neurological group, patient age group, target area and intervention type. The PEDro Scale is used to rate the methodological quality of RCTs, nonRCTs and CSs, with maximum obtainable methodological quality rating (MQR) of 10/10, 8/10 and 2/10 respectively. A search identified 1298 reports indexed in PsycBITE™. The largest proportion was SSDs (39%), followed by CSs (22%), RCTs (21%), non-RCTs (11%) and SRs (7%). The majority of reports was concerned with stroke (41%), traumatic brain injury (29%) and Alzheimer's and related dementias (22%). The most frequently investigated deficits were communication/language/speech disorders (24%); independent/self-care activities (19%); behaviour problems (17%); memory impairments (17%); anxiety, depression, stress, adjustment (15%). Approximately half of the RCTs, non-RCTs and CSs were rated for methodological quality. Mean MQR scores for RCTs, non-RCTs and CSs were 4.49, 2.85 and 1.15 respectively. While some PEDro criteria were met by a high proportion of RCTs and non-RCTs (≥ 70%), other criteria were only met by a small proportion of reports (as low as 1.6%). There was no significant difference in MQR scores between RCTs focusing on different neurological groups or target areas. Furthermore, there was no discernible improvement in MQR score for RCTs published over the last three decades. The methodological quality of studies investigating the efficacy of rehabilitation interventions in ABI has been consistently modest over several decades. This is largely attributable to poor adherence to fundamental tenets of research design, and requires urgent remediation. RCTs (and to a lesser extent, non-RCTs) are research methodologies which can potentially yield a high level of evidence, but only if they are adequately designed. PsycBITE™ has the facility to raise awareness of these issues and be instrumental in promoting EBCP in the field of ABI.