Attention Deficit Hyperactivity Disorder (ADHD)

A brief review of pharmaceutical interventions in neuro-psychological disorders

By: Dr Pieter Fourie

BACKGROUND: Sometimes children, especially during the school-going period from around 4 to 18 years, present with behavioural problems that will eventually be tied up to potentially three subgroups, i.e. attention, communication, and/or emotional related issues. According to the international DSM-V directive, these problems or issues are then again grouped in clinical diagnoses such as (i) attention deficit hyperactivity disorders with or without a number of co-morbidities (associated problems such as anxiety, oppositional defiant disorder, and mood dysregulation), (ii) autistic spectrum disorders (including Asperger’s, Pathological Demand Avoidance, and Pervasive Developmental Disorder not otherwise specified), and Tourette syndrome. Big names are often frightening to parents with children presenting with one of these entities. Be that as it may, the pharmaceutical approach (medicine) does not necessarily distinguish between the clinical diagnoses, but rather focusses on the presenting behavioural problems, such as anxiety, communication deficits, and concentration problems.

PATHOPHYSIOLOGY: In order to communicate information effectively, whether verbally or non-verbally, such as with writing, the brain activates a specific pathway, the so-called executive function network. By executing a task, the prefrontal cortex has to increase control over the decision-making process (increasing attention whilst inhibiting other inputs such as sound, visual, or tactile stimuli) followed by the execution of the task at hand. As an example, in order to perform a mathematical task, the prefrontal cortex has to initiate the process by activating the cortex problem-solving system. Once the solution has been derived, the information is then transferred to the motor cortex that will give an order to the hand to write down the answer. The basal ganglia will modulate the hand movement thereby streamlining the information whilst feedback is given via the eyes to ascertain that the correct answer is written down neatly. The emotional center will guard over the whole process from beginning to end and once completed, will convey a feeling of satisfaction to the cortex.

APPROACH:
To simplify matters, a very limited description is presented here. When evaluating a patient, attention is specifically given to five target domains namely:

1. Hyperactivity and inattention: These symptoms usually arise from a decrease of certain neurotransmitters i.e. dopamine and/or noradrenaline in the prefrontal cortex.

2. Behavioural issues: (aggression, self-harming, tantrums). Poor inhibitory control of emotions due to low dopamine in the central areas of the brain.

3. Communication: (dyspraxia, dyslexia, poor eye contact, and emotional avoidance). Poor or incomplete neural integration between pathways connecting important centres such as the prefrontal cortex, cortex, and basal ganglia.

4. Sleep disturbance: Usually a result of a shift in the circadian rhythm leading to wakefulness till around 23h00.

5. Mood disorders, including anxiety: Insufficient levels of serotonin in the emotional area.

MEDICATION OPTIONS: Although there are a multitude of options, the following medications are often prescribed.

1. Hyperactivity and inattention:
   Clonidine: An antihypertensive drug that is very effective in improving concentration.
   Methylphenidate: E.g. Ritalin (4 or LA: 8 hours), Concerta (12 hours) or Contramyl (12hours).
   Atomoxetine: E.g. Strattera or Inir.
   Tricyclic: Antidepressant: Ethipramine

2. Behavioural issues: (Aggression, self-harming, tantrums).
   Clonidine: See above.
   Antipsychotics: E.g. respiridone (given twice daily) or aripiprazole.
   Anti-convulsants: E.g. sodium valproate, lamotrigene or carbamazipine.
   Lithium: stabilises neural activity.

3. Communication: (Dyspraxia, dyslexia, poor eye contact and emotional avoidance).
   Antipsychotics: See above.
   SSRI: E.g. sertraline, fluoxetine or escitalopram.
   Both in combination.

4. Sleep disturbance:
   Circadian rhythm modifiers: E.g. melatonin or circadin.
   SSRI: See above.
   Mirtazapine: A new antidepressant.

5. Mood disorders including anxiety:
   SSRI: See above.
   Anticonvulsants: See above.
   Both in combination.

MONITORING:
Monitoring the response of the different medications, either alone or in combination, is absolutely essential, therefore regular feedback from the caretaker or patient will help to identify any side-effects, and determine efficacy and optimal dosage through incremental increasing of the dose.