Salivary determination of dim light melatonin onset as a tool in attention deficit hyperactivity disorder diagnosis

Abstract

Attention Deficit Hyperactivity Disorder (ADHD) has an estimated worldwide prevalence of 5.29%. Prevalence is estimated to be 6.48% (4.62–8.35) in children population and 2,74% (2.04–3.45) in adolescents. Biochemical, neuroimaging or electrophysiological tests are not available as confirmatory tools for ADHD clinical diagnosis. The aim of the present study is to determine if ADHA children show alterations of melatonin circadian rhythm by means of Dim Light Melatonin Onset (DLMO) salivary determination and to evaluate the suitability of this test as a tool in ADHD diagnosis. A sample ( N = 146) of 6–11 year old patients (98 ADHD children and 48 healthy controls) was selected and 730 determinations of salivary melatonin were carried out (5 per subject). Suitable samples were centrifuged 10 min to remove particulate material and frozen at −70 °C until analysis. Quantitative determination of melatonin was performed by a direct non-extraction ELISA assay using DSX analyser. DLMO levels for each patient were determined and were then classified as normal o altered (advanced, delayed and irregular). Detection of melatonin circadian secretion alterations was compared between groups by means of statistical analysis. The following parameter were calculated: Odds (ADHD/ no DLMO level disorder) = 1.36; Odds (ADHD/ DLMO level disorder) = 34.00; OR = 25.0 ( p = 0.0018); CI 95% (OR) = [3.3; 189.0]. DLMO determination as a test for ADHD detection had a SENSIBILITY of 34.69%, a SPECIFICITY of 97.92%, a positive predictive value (PPV) of 53,57% and a negative predictive value (NPV) of 95.58%. Salivary determination of DLMO cannot be considered as a screening tool due to the low sensibility in disorder detection but can be a useful confirmatory test in ADHD diagnosis. The high specificity of the proposed test makes it suitable for false positive diagnosis prevention. Participating children of the study and their parents for the selfless collaboration without which research studies such as this one would not be possible.