Salivary cortisol levels and dental anxiety in children with attention deficit hyperactivity disorder My Blomqvist 1 , Kirsten Holmberg 2 , Frank Lindblad 3 , Elisabeth Fernell 2 , Ulla Ek 4 , Gçran Dahllçf 1 1 Department of Pediatric Dentistry, Karolinska Institutet, Stockholm, Sweden; 2 Department of Neuropaediatrics, Astrid Lindgren Children's Hospital, Stockholm, Sweden; 3 Department of Public Health Sciences, Karolinska Institutet, Stockholm, Sweden; 4 Department of Psychology, Stockholm University, Sweden Attention deficit hyperactivity disorder (ADHD) is a condition that is defined according to a specific set of symptoms – inattention, hyperactivity, and impulsivity – as described in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) (1). Three subgroups of ADHD have been distinguished: the com- bined, the inattentive, and the hyperactive/impulsive type (2). The prevalence of ADHD has been reported to be  3–6% (2, 3), and boys are diagnosed with ADHD three to six times more often than girls (4), although it has been argued that girls with ADHD are underdiag- nosed owing to less prominent hyperactivity and fewer observable difficulties (5, 6). ADHD is frequently asso- ciated with other conditions, such as dyslexia, develop- mental coordination disorder, Tourette syndrome, oppositional defiant disorder, conduct disorder, and anxiety disorders (3, 7). In everyday life, children encounter situations that place explicit demands on them for adaptation and interplay. A dental visit is such a situation. In some children this is connected with fear and anxiety. The prevalence of dental anxiety in children has been repor- ted to be between 5.7 and 6.7% (8–10), with anxiety decreasing with increasing age (8). Our previous studies indicated that children with ADHD react differently from other children in a dental treatment situation (11). The child with ADHD experiences difficulties in inter- action, in staying focused, and in communication with the dentist (11). Children with ADHD may thus experi- ence more anxiety and stress in a dental examination setting. Stress is commonly defined as the physiological and psychological reactions that mobilize an organism’s defense against external or internal threats (stressors). The stress reaction includes activation of the hypotha- lamus–pituitary–adrenal (HPA) axis with the release of cortisol. Cortisol has a diurnal variation, and cortisol secretory activity is characterized by peak levels 20–30 min after awakening and a declining pattern thereafter (12). The diurnal rhythm of cortisol is a robust rhythm and is mainly unaffected by age, gender, or pubertal status (13). Salivary cortisol is known to be an indicator of the concentration of unbound cortisol in serum (14). Studies argue that children with ADHD have an altered cortisol response (15–17). Findings suggest that hyperactivity and impulsivity in children with ADHD might be associated with dysfunction of the HPA axis. Abnormal variations in diurnal salivary cortisol were found to be more frequent in severely and moderately hyperactive children with ADHD than in mildly hyperactive children or in an adult control group (15). Blomqvist M, Holmberg K, Lindblad F, Fernell E, Ek U, Dahllo ¨f G. Salivary cortisol levels and dental anxiety in children with attention deficit hyperactivity disorder. Eur J Oral Sci 2007; 115: 1–6. Ó 2007 The Authors. Journal compilation Ó 2007 Eur J Oral Sci Attention deficit hyperactivity disorder (ADHD) is a common developmental disor- der. The present study tested the hypotheses that children with ADHD, particularly those exhibiting severe hyperactivity and impulsivity, have a different stress reaction (measured by salivary cortisol) during a dental recall visit and are more dentally anxious than children in a control group. Eighteen children with ADHD and a control group of 71 children, all 13 yr of age, underwent a clinical dental examination and completed the Corah Dental Anxiety Scale (CDAS). Four saliva samples were gath- ered for analysis of cortisol: one prior to dental examination, one after, and two the following morning. The subgroup ADHD with hyperactivity/impulsivity had statis- tically significantly lower cortisol levels than the control group 30 min after awaken- ing. When cortisol values were plotted on a timeline, this subgroup always had lower cortisol concentrations than children in the control group. There was a significant correlation between CDAS scores and cortisol concentrations prior to the dental examination in both the ADHD and the control group. Behavioral expressions of anxiety in children with ADHD may be different from those in other children, not only due to the characteristics of their disorder, but also because of lower stress reactivity. Dr My Blomqvist, Department of Pediatric Dentistry, Karolinska Institutet, PO Box 4064, SE-141 04 Huddinge, Sweden Telefax: +46–8)7743395 E-mail: My.Blomqvist@ki.se Key words: ADHD; adolescent; behavioral science; cortisol; dental anxiety Accepted for publication November 2006 Eur J Oral Sci 2007; 115: 1–6 Printed in Singapore. All rights reserved Ó 2007 The Authors. Journal compilation Ó 2007 Eur J Oral Sci European Journal of Oral Sciences