Phenological response of tundra plants to background climate variation tested using the International Tundra Experiment.

The rapidly warming temperatures in high-latitude and alpine regions have the potential to alter the phenology of Arctic and alpine plants, affecting processes ranging from food webs to ecosystem trace gas fluxes. The International Tundra Experiment (ITEX) was initiated in 1990 to evaluate the effects of expected rapid changes in temperature on tundra plant phenology, growth and community changes using experimental warming. Here, we used the ITEX control data to test the phenological responses to background temperature variation across sites spanning latitudinal and moisture gradients. The dataset overall did not show an advance in phenology; instead, temperature variability during the years sampled and an absence of warming at some sites resulted in mixed responses. Phenological transitions of high Arctic plants clearly occurred at lower heat sum thresholds than those of low Arctic and alpine plants. However, sensitivity to temperature change was similar among plants from the different climate zones. Plants of different communities and growth forms differed for some phenological responses. Heat sums associated with flowering and greening appear to have increased over time. These results point to a complex suite of changes in plant communities and ecosystem function in high latitudes and elevations as the climate warms.

Developmental sources of variation in liability to adolescent substance use disorders.

This review provides a synthesis of the literature on the complex sequence of maturational, psychosocial, and neuroadaptive processes that lead to substance use disorders (SUD) in adolescence. A brief overview introduces the concepts of liability to SUD and epigenesis. A theory is presented explaining how affective, cognitive, and behavioral dysregulation in late childhood is exacerbated during early and middle adolescence by family and peer factors, as well as puberty, leading to substance use. Continued exacerbation of the three components of dysregulation by drug and non-drug stressors during late adolescence is posited to result in neuroadaptations that increase the likelihood of developing SUD, particularly in high-risk individuals. Implications for etiologic research as well as clinical and preventive interventions are discussed.

Hormonal and behavioral homeostasis in boys at risk for substance abuse.

This study modeled the influences of cortisol reactivity, androgens, age-corrected pubertal status, parental personality, family and peer dysfunction on behavioral self-regulation (BSR), in boys at high (HAR) and low average risk (LAR) for substance abuse. Differences between risk groups in cortisol and androgen concentrations, and cortisol reactivity were also examined. Subjects were 10- through 12-year-old sons of substance abusing fathers (HAR; n = 150) and normal controls (LAR; n = 147). A multidimensional construct of BSR was developed which utilized multiple measures and multiple informants. Boys reported on family dysfunction and deviant behavior among their peers. Parents reported on their propensity to physically abuse their sons, and their own number of DSM-III-R Antisocial Personality Disorder symptoms. Endocrine measures included plasma testosterone, dihydrotestosterone, and salivary cortisol. HAR boys, compared to LAR boys, had lower mean concentrations for testosterone, dihydrotestosterone, salivary cortisol prior to evoked related potential testing, and lower cortisol reactivity. The number of maternal Antisocial Personality Disorder symptoms, parental potential for physical abuse, degree of family dysfunction, and peer delinquency were significantly associated with BSR. Parental aggression antisocial personality symptoms and parental physical abuse potential are likely to influence sons' behavioral dysregulation and homeostatic stress reactivity. These key components of liability are posited to increase the likelihood of developing suprathreshold Psychoactive Substance Use Disorder (PSUD).

Child abuse potential in parents with histories of substance use disorder.

OBJECTIVE: To examine the relationship between parental history of substances use disorders (SUDs) and abuse potential. METHOD: Milner's (1986) Child Abuse Potential Inventory (CAPI) was administered to fathers and mothers (with and without histories of SUDs) of 10- to 12-year-old boys. RESULTS: Fathers and mothers with lifetime histories of SUDs had higher Abuse Scale scores and were more likely to score in the Elevated range (as determined by clinically significant cutoff scores) than parents without such histories. No differences were found between parents with current diagnoses of SUD and those with past (but not current) histories of SUD. Fathers and mothers with a partner who had a history of SUD were more likely to score in the Elevated range, regardless of their own SUD histories. Separate regression models revealed that, for both fathers and mothers, emotional dysregulation (positive and negative affectivity) predicted Abuse Scale scores. Additional contributors to Abuse Scale scores were SUD status in fathers, and lack of involvement with the child in mothers. CONCLUSIONS: History of SUDs in both fathers and mothers increases abuse potential. Contributors to abuse potential differed in fathers and mothers, underscoring the importance of examining parents separately in child maltreatment research.

Behavioral self-regulation: correlates and 2 year follow-ups for boys at risk for substance abuse.

This investigation demonstrated the heuristic construct of behavioral self-regulation (BSR) as a salient component of the liability to substance abuse. Three dimensions of childhood behaviour were employed to create a dimensional model of BSR: inattention, impulsivity/hyperactivity and aggressivity. Multiple measures and multiple informants were employed to develop indices of the three traits in a sample of 10-12 year old sons of substance abusing fathers (high risk (HR); n = 180) and normal controls (low average risk (LAR); n = 200). Informants included mothers, boys and their teachers. The results confirmed the presence of a first-order latent trait of BSR. HR boys had significantly higher scores on BSR than LAR boys. Concurrent validity of the BSR trait scores was supported by significant associations with measures of family dysfunction, deviant peer affiliations and poor school performance. These latter problems are commonly prodromal to substance abuse. Predictive validity of the BSR trait baseline scores (age 10-12 years) was supported at 2 year follow-up by significant associations of BSR scores with magnitude of deviant peer affiliations; trends toward significance were found for family dysfunction and poor school performance. Taken together, these results confirm and extend previous findings which indicate that poor BSR is prodromal to substance abuse.

Clinician assessment of psychiatric comorbidity and alcoholism severity in adult alcoholic inpatients.

Although psychiatric comorbidity and alcoholism severity are risk factors for poor outcomes in treating alcoholism, little is known about whether clinicians assess these conditions accurately. In this study we evaluated four clinicians' assessments of two indicators of alcoholism severity and three psychiatric co-morbidities in 78 inpatients in their third to seventh day of hospitalization in alcohol treatment programs. Clinicians overestimated the number of days drinking in 28% of subjects, and the number of drinks per drinking day in 37% of subjects. Clinicians underestimated alcohol consumption for patients with higher incomes. Clinicians correctly diagnosed 67% of 18 subjects with antisocial personality disorder, 65% of 26 with major depression, and 89% of 28 with drug abuse. These preliminary results need to be replicated in larger samples of clinicians to determine whether interventions are needed to improve the recognition of important prognostic factors in the treatment of alcoholic patients.