Color, chlorophyll a, and suspended solids effects on Secchi depth in lakes: implications for trophic state assessment.

Secchi depth (SD), a primary metric to assess trophic state, is controlled in many lakes by algal densities, measured as chlorophyll-a (chl-a) concentration. Two other optically related water quality variables also directly affect SD: non-algal suspended solids (SSNA ) and colored dissolved organic matter (CDOM, expressed as the absorption coefficient at 440 nm, a440 ). Using a database of ~1,460 samples from ~625 inland lake basins in Minnesota and two other Upper Midwest states, Wisconsin and Michigan, we analyzed relationships among these variables, with special focus on CDOM levels that influence SD values and the Minnesota SD standards used to assess eutrophication impairment of lakes. Log-transformed chl-a, total suspended solids (TSS), and SD were strongly correlated with each other; log(a440 ) had major effects on log(SD) but was only weakly correlated with log(chl-a) and log(TSS). Multiple regression models for log(SD) and 1/SD based on the three driving variables (chl-a, SSNA , and CDOM) explained ~80% of the variance in SD in the whole data set, but substantial differences in the form of the best-fit relationships were found between major ecoregions. High chl-a concentrations (> 50 µg/L) and TSS (> 20 mg/L) rarely occurred in lakes with high CDOM (a440  > ~4 m-1 ), and all lakes with a440  > 8 m-1 had SD ≤ 2.0 m despite low chl-a values (<10 µg/L) in most lakes. Further statistical analyses revealed that CDOM has significant effects on SD at a440 values > ~ 4 m-1 . Thus, SD is not an accurate trophic state metric in moderately to highly colored lakes, and Minnesota's 2-m SD criterion should not be the sole metric to assess eutrophication impairment in warm/cool-water lakes of the Northern Lakes and Forest ecoregion. More generally, trophic state assessments using SD in regions with large landscape sources of CDOM need to account for effects of CDOM on SD.

Are obstetrical, perinatal, and infantile difficulties associated with pediatric bipolar disorder?

OBJECTIVES: Despite increasing acknowledgement of bipolar disorder (BD) in childhood, there is a paucity of literature that has investigated obstetrical, perinatal, and infantile difficulties and their potential link with BD. To this end, we examined difficulties during delivery, immediate post-birth, and infancy and the association with BD in childhood. METHODS: From two similarly designed, ongoing, longitudinal, case-control family studies of pediatric BD (N = 327 families), we analyzed 338 children and adolescents [mean (± standard deviation) age: 12.00 ± 3.37 years]. We stratified them into three groups: healthy controls (N = 98), BD probands (N = 120), and their non-affected siblings (N = 120). All families were comprehensively assessed with a structured psychiatric diagnostic interview for psychopathology and substance use. Mothers were directly questioned regarding the pregnancy, delivery, and infancy difficulties that occurred with each child using a module from the Diagnostic Interview for Children and Adolescents-Parent Version (DICA-P). RESULTS: Mothers of BD subjects were more likely to report difficulties during infancy than mothers of controls [odds ratio (95% confidence interval) = 6.6 (3.0, 14.6)]. Specifically, children with BD were more likely to have been reported as a stiffened infant [7.2 (1.1, 47.1)] and more likely to have experienced 'other' infantile difficulties [including acting colicky; 4.9 (1.3, 18.8)] compared to controls. We found no significant differences between groups in regards to obstetrical or perinatal difficulties (all p values > 0.05). CONCLUSIONS: While our results add to previous literature on obstetrical and perinatal difficulties and BD, they also highlight characteristics in infancy that may be prognostic indicators for pediatric BD.

Further Evidence for Smoking and Substance Use Disorders in Youth With Bipolar Disorder and Comorbid Conduct Disorder.

OBJECTIVE: Bipolar disorder (BPD) is a highly morbid disorder increasingly recognized in adolescents. The aim of this study was to examine the relative risk for substance use disorders (SUDs; alcohol or drug abuse or dependence) and cigarette smoking in adolescents with BPD. METHODS: We evaluated the relative risk for SUDs and cigarette smoking in a case-controlled, 5-year prospective follow-up of adolescents with (n = 105, mean ± SD baseline age = 13.6 ± 2.5 years) and without ("controls"; n = 98, baseline age = 13.7 ± 2.1 years) BPD. Seventy-three percent of subjects were retained at follow-up (BPD: n = 68; controls: n = 81; 73% reascertainment). Our main outcomes were assessed by blinded structured interviews for DSM-IV criteria. RESULTS: Maturing adolescents with BPD, compared to controls, were more likely to endorse higher rates of SUD (49% vs 26%; hazard ratio [HR] = 2.0; 95% confidence interval (CI), 1.1-3.6; P = .02) and cigarette smoking (49% vs 17%; HR = 2.9; 95% CI, 1.4-6.1; P = .004), as well as earlier onset of SUD (14.9 ± 2.6 [SD] years vs 16.5 ± 1.6 [SD] years; t = 2.6; P = .01). Subjects with conduct disorder (CD) were more likely to have SUD and nicotine dependence than subjects with BPD alone or controls (all P values < .05). When we added conduct disorder to the model with socioeconomic status and parental SUD, all associations lost significance (all P values > .05). Subjects with the persistence of a BPD diagnosis were also more likely to endorse cigarette smoking and SUD in comparison to those who lost a BPD diagnosis or controls at follow-up. CONCLUSIONS: The results provide further evidence that adolescents with BPD, particularly those with comorbid CD, are significantly more likely to endorse cigarette smoking and SUDs when compared to their non-mood disordered peers. These findings indicate that youth with BPD should be carefully monitored for comorbid CD and the development of cigarette smoking and SUDs.

Difficulties in emotional regulation and substance use disorders: a controlled family study of bipolar adolescents.

BACKGROUND: Self-regulatory mechanisms appear etiologically operant in the context of both substance use disorders (SUD) and bipolar disorder (BD), however, little is known about the role of deficits in emotional self-regulation (DESR) as it relates to SUD in context to mood dysregulation. To this end, we examined to what extent DESR was associated with SUD in a high-risk sample of adolescents with and without BD. METHODS: 203 families were assessed with a structured psychiatric interview. Using the Child Behavior Checklist (CBCL), a subject was considered to have DESR when he or she had an average elevation of 1 standard deviation (SD) above the norm on 3 clinical scale T scores (attention, aggression, and anxiety/depression; scores: 60 × 3 ≥ 180). RESULTS: Among probands and siblings with CBCL data (N=303), subjects with DESR were more likely to have any SUD, alcohol use disorder, drug use disorder, and cigarette smoking compared to subjects with scores <180 (all p values <0.001), even when correcting for BD. We found no significant differences in the risk of any SUD and cigarette smoking between those with 1SD and 2SD above the mean (all p values >0.05). Subjects with cigarette smoking and SUD had more DESR compared to those without these disorders. CONCLUSIONS: Adolescents with DESR are more likely to smoke cigarettes and have SUD. More work is needed to explore DESR in longitudinal samples.