Here are five papers on difficulties experienced by adolescents.  A couple of the papers are follow-up studies.  Colman et al looked at the multiple negative personal & relationship outcomes in a UK national cohort of adolescents with conduct problems followed over 40 years.  Wentz et al studied the somewhat more encouraging 18 year outcomes of a group of adolescents suffering from anorexia. 

A couple of the papers are about depression.  Kennard and colleagues report again on the well-known Treatment for Adolescents with Depression Study (TADS) comparing antidepressants, cognitive-behavioural therapy and combined treatment.  By about six months there was little difference between the three forms of treatment.  At nine months the remission rate for intent-to-treat cases was 60% overall.  Primack et al investigated the association between electronic media use in adolescence and subsequent depression in young adulthood.  They reported "Controlling for all covariates including baseline Center for Epidemiologic Studies-Depression Scale score, those reporting more television use had significantly greater odds of developing depression."

In the fifth of these papers, O'Connor and colleagues studied the prevalence of self-harm in Scottish adolescents.  They found that - as in England - approximately 14% of those surveyed reported self-harm.  "The majority (71%) of those who had self-harmed had done so in the past 12 months and girls were approximately 3.4 times more likely to report self-harm than boys."

Colman, I., J. Murray, et al. (2009). "Outcomes of conduct problems in adolescence: 40 year follow-up of national cohort." BMJ 338(jan08_2): a2981-.  [Free Full Text] 
Objective To describe long term outcomes associated with externalising behaviour in adolescence, defined in this study as conduct problems reported by a teacher, in a population based sample. Design Longitudinal study from age 13-53. Setting The Medical Research Council National Survey of Health and Development (the British 1946 birth cohort). Participants 3652 survey members assessed by their teachers for symptoms of externalising behaviour at age 13 and 15. Main outcome measures Mental disorder, alcohol abuse, relationship difficulties, highest level of education, social class, unemployment, and financial difficulties at ages 36-53. Results 348 adolescents were identified with severe externalising behaviour, 1051 with mild externalising behaviour, and 2253 with no externalising behaviour. All negative outcomes measured in adulthood were more common in those with severe or mild externalising behaviour in adolescence, as rated by teachers, compared with those with no externalising behaviour. Adolescents with severe externalising behaviour were more likely to leave school without any qualifications (65.2%; adjusted odds ratio 4.0, 95% confidence interval 2.9 to 5.5), as were those with mild externalising behaviour (52.2%; 2.3, 1.9 to 2.8), compared with those with no externalising behaviour (30.8%). On a composite measure of global adversity throughout adulthood that included mental health, family life and relationships, and educational and economic problems, those with severe externalising behaviour scored significantly higher (40.1% in top quarter), as did those with mild externalising behaviour (28.3%), compared with those with no externalising behaviour (17.0%). Conclusions Adolescents who exhibit externalising behaviour experience multiple social and health impairments that adversely affect them, their families, and society throughout adult life.

Wentz, E., I. C. Gillberg, et al. (2009). "Adolescent-onset anorexia nervosa: 18-year outcome." British Journal of Psychiatry 194(2): 168-174.  [Abstract/Full Text] 
Background The long-term outcome of anorexia nervosa is insufficiently researched. Aims To study prospectively the long-term outcome and prognostic factors in a representative sample of people with teenage-onset anorexia nervosa. Method Fifty-one people with anorexia nervosa, recruited by community screening and with a mean age at onset of 14 years were compared with 51 matched comparison individuals at a mean age of 32 years (18 years after disorder onset). All participants had been examined at ages 16 years, 21 years and 24 years. They were interviewed for Axis I psychiatric disorders and overall outcome (Morgan-Russell assessment schedule and the Global Assessment of Functioning). Results There were no deaths. Twelve per cent (n=6) had a persisting eating disorder, including three with anorexia nervosa. Thirty-nine per cent of the anorexia nervosa group met the criteria for at least one psychiatric disorder. The general outcome was poor in 12%. One in four did not have paid employment owing to psychiatric problems. Poor outcome was predicted by premorbid obsessive-compulsive personality disorder, age at onset of anorexia nervosa and autistic traits. Conclusions The 18-year outcome of teenage-onset anorexia nervosa is favourable in respect of mortality and persisting eating disorder.

Kennard, B. D., S. G. Silva, et al. (2009). "Remission and Recovery in the Treatment for Adolescents With Depression Study (TADS): Acute and Long-Term Outcomes." Journal of Amer Academy of Child & Adolescent Psychiatry 48(2): 186-195 10.1097/CHI.0b013e31819176f9.  [Abstract/Full Text] 
Objective: We examine remission rate probabilities, recovery rates, and residual symptoms across 36 weeks in the Treatment for Adolescents with Depression Study (TADS). Method: The TADS, a multisite clinical trial, randomized 439 adolescents with major depressive disorder to 12 weeks of treatment with fluoxetine, cognitive-behavioral therapy, their combination, or pill placebo. The pill placebo group, treated openly after week 12, was not included in the subsequent analyses. Treatment differences in remission rates and probabilities of remission over time are compared. Recovery rates in remitters at weeks 12 (acute phase remitters) and 18 (continuation phase remitters) are summarized. We also examined whether residual symptoms at the end of 12 weeks of acute treatment predicted later remission. Results: At week 36, the estimated remission rates for intention-to-treat cases were as follows: combination, 60%; fluoxetine, 55%; cognitive-behavioral therapy, 64%; and overall, 60%. Paired comparisons reveal that, at week 24, all active treatments converge on remission outcomes. The recovery rate at week 36 was 65% for acute phase remitters and 71% for continuation phase remitters, with no significant between-treatment differences in recovery rates. Residual symptoms at the end of acute treatment predicted failure to achieve remission at weeks 18 and 36. Conclusions: Most depressed adolescents in all three treatment modalities achieved remission at the end of 9 months of treatment.

Primack, B. A., B. Swanier, et al. (2009). "Association Between Media Use in Adolescence and Depression in Young Adulthood: A Longitudinal Study." Arch Gen Psychiatry 66(2): 181-188.  [Abstract/Full Text]
Context Although certain media exposures have been linked to the presence of psychiatric conditions, few studies have investigated the association between media exposure and depression. Objective To assess the longitudinal association between media exposure in adolescence and depression in young adulthood in a nationally representative sample. Design Longitudinal cohort study. Setting and Participants We used the National Longitudinal Survey of Adolescent Health (Add Health) to investigate the relationship between electronic media exposure in 4142 adolescents who were not depressed at baseline and subsequent development of depression after 7 years of follow-up. Main Outcome Measure Depression at follow-up assessed using the 9-item Center for Epidemiologic Studies-Depression Scale. Results Of the 4142 participants (47.5% female and 67.0% white) who were not depressed at baseline and who underwent follow-up assessment, 308 (7.4%) reported symptoms consistent with depression at follow-up. Controlling for all covariates including baseline Center for Epidemiologic Studies-Depression Scale score, those reporting more television use had significantly greater odds of developing depression (odds ratio [95% confidence interval], 1.08 [1.01-1.16]) for each additional hour of daily television use. In addition, those reporting more total media exposure had significantly greater odds of developing depression (1.05 [1.0004-1.10]) for each additional hour of daily use. We did not find a consistent relationship between development of depressive symptoms and exposure to videocassettes, computer games, or radio. Compared with young men, young women were less likely to develop depression given the same total media exposure (odds ratio for interaction term, 0.93 [0.88-0.99]). Conclusion Television exposure and total media exposure in adolescence are associated with increased odds of depressive symptoms in young adulthood, especially in young men.

O'Connor, R. C., S. Rasmussen, et al. (2009). "Self-harm in adolescents: self-report survey in schools in Scotland." British Journal of Psychiatry 194(1): 68-72.  [Abstract/Full Text]  
Background The suicide rate in Scotland is twice as high as that in England. However, the prevalence of self-harm is unknown. Aims To determine the prevalence of self-harm in adolescents in Scotland and the factors associated with it. Method A total of 2008 pupils aged 15-16 years completed an anonymous lifestyle and coping survey. Information was obtained on demographic characteristics, lifestyle, life events and problems, social influences, psychological variables and self-harm. Results Self-harm was reported by 13.8% of the respondents. The majority (71%) of those who had self-harmed had done so in the past 12 months and girls were approximately 3.4 times more likely to report self-harm than boys. In multivariate analyses, smoking, bullying, worries about sexual orientation, self-harm by family and anxiety were associated with self-harm in both genders. In addition, drug use, physical abuse, serious boy/girlfriend problems, self-harm by friends and low levels of optimism were also associated with self-harm in girls. Conclusions Despite markedly different national suicide rates, the prevalence of self-harm in Scotland is similar to that in England with girls at least three times more likely to report self-harm than boys. The findings suggest a role for emotional literacy programmes in schools and highlight the importance of promoting positive mental health among adolescents.