The prevalence of Attention Deficit Hyperactivity Disorder (ADHD) in children with Cerebral Palsy (CP) is 19%. Whilst there is evidence that methylphenidate is an efficacious first line therapy for patients with ADHD, there is a lack of literature describing atomoxetine use in ADHD with comorbid CP.

Here we report the case of a 17-year old Caucasian female with ADHD and CP. The patient was referred to Child and Adolescent Mental Health Services (CAMHS) for ongoing anxiety following extensive orthopaedic surgery, which was managed with sertraline and concurrent Cognitive Behavioural Therapy.

A CAMHS assessment led to her subsequent diagnosis of ADHD resulting in an initial treatment of low-dose methylphenidate (Ritalin). This was discontinued after four days due to progressive headache, tachycardia, and unilateral leg restlessness. The patient was hesitant to commence lisdexamfetamine, a second line stimulant medication, due to the possibility of similar adverse side effects.

Atomoxetine (20mg/day) was commenced for a month then increased to 30mg/day. After five months, it was discontinued. The patient reported no significant improvements to attention or concentration, but reported a later onset of escalating anxiety prior to discontinuation. Consultation revealed that the patient's anxiety may be attributed to biopsychosocial factors unrelated to pharmacotherapy, but could not discount the possibility that this was a side effect of atomoxetine. Following the discontinuation of atomoxetine, the patient and her carer were amenable to trialling lisdexamfetamine.

Previous data have demonstrated that patients with CP have lower tolerance to particular pharmacological agents, therefore atomoxetine was started at a low dose (20mg/day) to permit a gradual titration up to the recommended therapeutic dose. Worsening anxiety whilst on atomoxetine (30mg/day) may be a result of one or a combination of the following: (1) long-term side effect, (2) subtherapeutic dose response, (3) identified precipitating and perpetuating psychosocial factors, particularly in the school setting.

The case report demonstrated an acceptable safety profile for the use of atomoxetine in a young person with ADHD and comorbid CP. The expected therapeutic benefits of atomoxetine for ADHD may have been offset by extenuating biopsychosocial factors. Further research is needed to determine whether there exists a causal relationship between atomoxetine therapy and worsened anxiety within this patient group. Furthermore, this case highlights the importance of understanding the complexities of ADHD treatment in patients with confounding environmental factors and comorbid neurological disorders.