Content and Process of Adolescent Suicide Ideation: Implications for Risk Assessment

This study examined differences in the content and process of suicide ideation between adolescents presenting with recent suicide ideation or a suicide attempt in clinical settings. Across two combined study samples, adolescents (N = 229; 79% female; 73% Hispanic/Latine), ages 12-19, presenting with a recent suicide attempt, recent suicide ideation with a past suicide attempt history, or recent suicide ideation with no past suicide attempt history were interviewed in detail about the process and content of their suicide ideation. The group with suicide ideation and a past suicide attempt more often reported that their recent ideation lasted greater than 4 h compared to those with suicide ideation but no past suicide attempt history. The suicide attempt group more often considered ingestion as their first method of attempt, compared to the other two suicide ideation groups, and less often considered "other" methods (e.g., jumping from a height or onto train/traffic, hanging). Wish to die was lower in the ideation-only group, compared to both other groups. Separate analyses from Study 2 suggested that the majority of adolescents' suicide ideation contained imagery; however, a higher proportion of adolescents with suicide ideation and a past suicide attempt reported imagery in their ideation than those with ideation but no past attempt. Understanding what adolescents think about when they consider suicide and how they think about it may be informative about risk of a suicide attempt.

Being certain that negative events will happen or that positive events will not happen: Depressive predictive certainty and change in suicide ideation over time

INTRODUCTION

Relatively little research has examined the precise components of hopelessness that increase vulnerability to suicidal thinking. We examined whether certainty about an absence of positive future outcomes (Certainty-AP) would more strongly predict suicide ideation over time than certainty about negative future outcomes (Certainty-N).

METHOD

Young adults (N = 208), ages 18-34 (M = 19.08, SD = 2.22), with either recent suicide ideation, suicide attempt history, or past-year psychiatric diagnosis were assessed four times over 18 months.

RESULTS

We used multilevel modeling to assess within-participant differences in suicide ideation over time. Both Certainty-AP and Certainty-N predicted later suicide ideation above and beyond generalized hopelessness and depressive symptoms, when examined in separate models. However, Certainty-AP emerged as a stronger predictor of suicide ideation than Certainty-N when examined in the same model.

DISCUSSION

These findings suggest that certainty about an absence of positive future outcomes may have a more unique prospective relationship to SI than certainty about the presence of negative future outcomes. We discuss clinical and theoretical implications of these findings.

Regulation of ethanol intake under chronic mild stress: roles of dopamine receptors and transporters

Studies have shown that exposure to chronic mild stress decreases ethanol intake and preference in dopamine D2 receptor wild-type mice (Drd2 (+/+)), while it increases intake in heterozygous (Drd2 (+/-)) and knockout (Drd2 (-/-)) mice. Dopaminergic neurotransmission in the basal forebrain plays a major role in the reinforcing actions of ethanol as well as in brain responses to stress. In order to identify neurochemical changes associated with the regulation of ethanol intake, we used in vitro receptor autoradiography to measure the levels and distribution of dopamine D1 and D2 receptors and dopamine transporters (DAT). Receptor levels were measured in the basal forebrain of Drd2 (+/+), Drd2 (+/-), and Drd2 (-/-) mice belonging to one of four groups: control (C), ethanol intake (E), chronic mild stress exposure (S), and ethanol intake under chronic mild stress (ES). D2 receptor levels were higher in the lateral and medial striatum of Drd2 (+/+) ES mice, compared with Drd2 (+/+) E mice. Ethanol intake in Drd2 (+/+) mice was negatively correlated with striatal D2 receptor levels. D2 receptor levels in Drd2(+/-) mice were the same among the four treatment groups. DAT levels were lower in Drd2(+/-) C and Drd2 (-/-) C mice, compared with Drd2 (+/+) C mice. Among Drd2(+/-) mice, S and ES groups had higher DAT levels compared with C and E groups in most regions examined. In Drd2(-/-) mice, ethanol intake was positively correlated with DAT levels in all regions studied. D1 receptor levels were lower in Drd2(+/-) and Drd2(-/-) mice, compared with Drd2(+/+), in all regions examined and remained unaffected by all treatments. The results suggest that in normal mice, ethanol intake is associated with D2 receptor-mediated neurotransmission, which exerts a protective effect against ethanol overconsumption under stress. In mice with low Drd2 expression, where DRD2 levels are not further modulated, ethanol intake is associated with DAT function which is upregulated under stress leading to ethanol overconsumption.

Förster resonance energy transfer microscopy and spectroscopy for localizing protein-protein interactions in living cells

The fundamental theory of Förster resonance energy transfer (FRET) was established in the 1940s. Its great power was only realized in the past 20 years after different techniques were developed and applied to biological experiments. This success was made possible by the availability of suitable fluorescent probes, advanced optics, detectors, microscopy instrumentation, and analytical tools. Combined with state-of-the-art microscopy and spectroscopy, FRET imaging allows scientists to study a variety of phenomena that produce changes in molecular proximity, thereby leading to many significant findings in the life sciences. In this review, we outline various FRET imaging techniques and their strengths and limitations; we also provide a biological model to demonstrate how to investigate protein-protein interactions in living cells using both intensity- and fluorescence lifetime-based FRET microscopy methods.

Chronic mild stress increases alcohol intake in mice with low dopamine D2 receptor levels

Alcohol use disorders emerge from a complex interaction between environmental and genetic factors. Stress and dopamine D2 receptor levels (DRD2) have been shown to play a central role in alcoholism. To better understand the interactions between DRD2 and stress in ethanol intake behavior, we subjected Drd2 wild-type (+/+), heterozygous (+/-), and knockout (-/-) mice to 4 weeks of chronic mild stress (CMS) and to an ethanol two-bottle choice during CMS weeks 2-4. Prior to and at the end of the experiment, the animals were tested in the forced swim and open field tests. We measured ethanol intake and preference, immobility in the force swim test, and activity in the open field. We show that under no CMS, Drd2+/- and Drd2-/- mice had lower ethanol intake and preference compared with Drd2+/+. Exposure to CMS decreased ethanol intake and preference in Drd2+/+ and increased them in Drd2+/- and Drd2-/- mice. At baseline, Drd2+/- and Drd2-/- mice had significantly lower activity in the open field than Drd2+/+, whereas no genotype differences were observed in the forced swim test. Exposure to CMS increased immobility during the forced swim test in Drd2+/- mice, but not in Drd2+/+ or Drd2-/- mice, and ethanol intake reversed this behavior. No changes were observed in open field test measures. These findings suggest that in the presence of a stressful environment, low DRD2 levels are associated with increased ethanol intake and preference and that under this condition, increased ethanol consumption could be used as a strategy to alleviate negative mood.