Updated: Oct 2
By Sally Goddard Blythe MSc.
In the wake of the pandemic and the social, emotional and educational challenges it brought with it, there appears to be an increase in the number of children and adults manifesting and experiencing symptoms of ADHD.
ADHD is classified as a neurodevelopmental disorder involving inattention across six or more scales which include specific symptoms under the headings of: Inattention, hyperactivity and impulsivity. These symptoms, which are not solely a manifestation of oppositional behavior, defiance, hostility, or failure to understand tasks or instructions, are inconsistent with developmental level, have persisted for at least six months and have a negative impact on social, academic and occupational function.
One of the challenges for diagnosis of ADHD is that there is not a set of objective, standard laboratory tests to definitively show what ADHD is. Diagnosis still largely relies on subjective observations and check lists carried out in a several environments. These criteria for diagnosis describe a list of symptoms but do not point to underlying causes in terms of neurological or biochemical function.
A number of brain regions have been implicated in the manifestation of ADHD:
The frontal cortex which controls high-level functions including attention, executive function and organisation. Research has shown that a particular type of brain wave (beta), which facilitates alert and sustained attention is not firing at a fast or consistent enough rate to regulate attention in some people with ADHD.
The limbic system which is linked to higher and lower regions of the brain regulates emotions, memories and arousal. It communicates using neurotransmitters – or chemical messengers – which transmit messages between neurons or from neurons to muscles. Deficiency in the availability or regulation of two neurotransmitters – norepinephrine and dopamine – have been implicated in ADHD. Availability and regulation can be influenced by nutritional status.
The basal ganglia, a group of subcortical nuclei within the brain, primarily responsible for motor control but also other roles including motor learning, executive functions and emotional behaviours playing an important role in reward and reinforcement, addictive behaviours and habit formation. It is thought that the basal ganglia has several loops where higher and lower projections interact and are involved in selecting and inhibiting simultaneously occurring events and signals. A deficiency in the functioning of the basal ganglia can contribute to inattention and impulsivity.
The Reticular Activating System is a network of neurons located in the brain stem projecting to parts of the brain responsible for hormone release, filtering of sensory information and levels of arousal including the sleep/wake cycle and synchronisation of brain wave function in the cortex (highest level of the brain). This is the major relay system among the many pathways that enter & leave the brain. A deficiency here can cause hyper or under-arousal, inattention, impulsivity, or hyperactivity.
The cerebellum traditionally known to be involved in the fine tuning of motor output has been shown to be involved in a number of cognitive functions including the rapid shifting of attention between sensory different modalities. Some research has indicated that areas of the cerebellum are smaller in some children diagnosed with ADHD and Autistic Spectrum Disorder (ASD).
Symptoms of ADHD can also emerge as a result of trauma, neglect and/or attachment issues when there is a disassociation between parts of the brain involved in emotional responses to separation, trauma, abuse or neglect.
Social and environmental factors can also contribute to the onset of symptoms of inattention and hyperactivity. E-media while providing a plethora of information and entertainment can also contribute to information overload, problems with transferring and storing information into long term memory, distraction, altered dopamine regulation and paradoxically, difficulty shifting attention away from e-media activities.
Over a prolonged period of time, the brain can become attuned to rapid shifts of attention to competing stimuli in the general environment, taking in information provided in bytes rather than a narrative, the need to remember information that is only one page of a screen at a time and over-reliance on screen information versus processing auditory information in the here and now. The underlying causes of this type of inattention and poor short- term memory are different from the neurological factors mentioned above, but the effects are similar and, it appears may be beginning to impact adults as a secondary response to the stresses of modern life as well as children.
In order to find effective solutions, it is important to discover underlying factors in each individual case. In the United States, one centre insists on carrying out a 24 hour EEG before making any recommendations for medication. Unfortunately, this level of rigorous assessment is not generally available. Medication is sometimes needed and is effective, but it is not the solution for all.
Nutritional intervention can help in some cases as can training of sensory systems to reduce hyper-sensitivity and hyper-arousal, motor training, sensory-motor programmes and various types of neurofeedback, but the crucial factor is understanding why?
While the incidence of ADHD seems to be increasing, how much of this is a direct product of underlying neurological or biochemical factors and how much is being fed by modern lifestyles is a “grey” area. Over-diagnosis based solely on results obtained from check lists may provide some comfort in having a label which describes various behaviours and anxieties, but it does not necessarily point to effective solutions.