title: Methylphenidate ameliorates depressive comorbidity in ADHD children without any modification on differences in serum melatonin concentration between ADHD subtypes.
abstract: The vast majority of Attention-deficit/hyperactivity disorder (ADHD) patients have other associated pathologies, with depressive symptoms as one of the most prevalent. Among the mediators that may participate in ADHD, melatonin is thought to regulate circadian rhythms, neurological function and stress response. To determine (1) the serum baseline daily variations and nocturnal excretion of melatonin in ADHD subtypes and (2) the effect of chronic administration of methylphenidate, as well as the effects on symptomatology, 136 children with ADHD (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision: DSM-IV-TR criteria) were divided into subgroups using the "Children's Depression Inventory" (CDI). Blood samples were drawn at 20:00 and 09:00 h, and urine was collected between 21:00 and 09:00 h, at inclusion and after 4.61 ± 2.29 months of treatment. Melatonin and its urine metabolite were measured by radioimmunoassay RIA. Factorial analysis was performed using STATA 12.0. Melatonin was higher predominantly in hyperactive-impulsive/conduct disordered children (PHI/CD) of the ADHD subtype, without the influence of comorbid depressive symptoms. Methylphenidate ameliorated this comorbidity without induction of any changes in the serum melatonin profile, but treatment with it was associated with a decrease in 6-s-melatonin excretion in both ADHD subtypes.
  
  
  CONCLUSIONS
  In untreated children, partial homeostatic restoration of disrupted neuroendocrine equilibrium most likely led to an increased serum melatonin in PHI/CD children. A differential cerebral melatonin metabolization after methylphenidate may underlie some of the clinical benefit.
authors.affiliation: Neuropediatric, Neuropsicology and Early intervention Unit Pediatric Service, Clinico San Cecilio Hospital, 18012 Granada, Spain. ireso77@hotmail.com.
authors.forename: Isabel
authors.initials: I
authors.lastname: Cubero-Millán
authors.affiliation: Neuropediatric, Neuropsicology and Early intervention Unit Pediatric Service, Clinico San Cecilio Hospital, 18012 Granada, Spain. amolinac@ugr.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Molina-Carballo
authors.affiliation: Neuropediatric, Neuropsicology and Early intervention Unit Pediatric Service, Clinico San Cecilio Hospital, 18012 Granada, Spain. isacubero83@hotmail.com.
authors.forename: Irene
authors.initials: I
authors.lastname: Machado-Casas
authors.affiliation: Neuropediatric, Neuropsicology and Early intervention Unit Pediatric Service, Clinico San Cecilio Hospital, 18012 Granada, Spain. ia_luisita@hotmail.com.
authors.forename: Luisa
authors.initials: L
authors.lastname: Fernández-López
authors.affiliation: Neuropediatric, Neuropsicology and Early intervention Unit Pediatric Service, Clinico San Cecilio Hospital, 18012 Granada, Spain. todosylvia@hotmail.com.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Martínez-Serrano
authors.affiliation: Neuropediatric, Neuropsicology and Early intervention Unit Pediatric Service, Clinico San Cecilio Hospital, 18012 Granada, Spain. pilartortosa@yahoo.es.
authors.forename: Pilar
authors.initials: P
authors.lastname: Tortosa-Pinto
authors.affiliation: Neuropediatric, Neuropsicology and Early intervention Unit Pediatric Service, Clinico San Cecilio Hospital, 18012 Granada, Spain. aida.ruiz@hotmail.com.
authors.forename: Aida
authors.initials: A
authors.lastname: Ruiz-López
authors.affiliation: Biostatistical Department, School of Medicine, Granada University, 18140 Granada, Spain. jdluna@ugr.es.
authors.forename: Juan-de-Dios
authors.initials: JD
authors.lastname: Luna-del-Castillo
authors.affiliation: Neuropediatric, Neuropsicology and Early intervention Unit Pediatric Service, Clinico San Cecilio Hospital, 18012 Granada, Spain. juberos@ugr.es.
authors.forename: José
authors.initials: J
authors.lastname: Uberos
authors.affiliation: Neuropediatric, Neuropsicology and Early intervention Unit Pediatric Service, Clinico San Cecilio Hospital, 18012 Granada, Spain. amunozh@ugr.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Muñoz-Hoyos
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000097:blood / Q000145:classification / Q000150:complications / Q000188:drug therapy*; D000697:Central Nervous System Stimulants / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm; D019955:Conduct Disorder / Q000097:blood / Q000150:complications; D003863:Depression / Q000150:complications / Q000188:drug therapy*; D005260:Female; D006706:Homeostasis; D006801:Humans; D007175:Impulsive Behavior; D008297:Male; D008550:Melatonin / Q000097:blood*; D008774:Methylphenidate / Q000627:therapeutic use*; D010555:Personality Inventory; D020919:Sleep Disorders, Intrinsic / Q000097:blood / Q000209:etiology
chemical_list: D000697:Central Nervous System Stimulants; D008774:Methylphenidate; D008550:Melatonin