According to the Diagnostic and Statistical Manual of Mental Disorders (DSM), ADHD is a neurodevelopmental disorder, reflecting a persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or development.
The symptoms of ADHD are not solely a manifestation of oppositional behaviour, defiance, hostility, or failure to understand tasks or instructions.
Prof Philip Asherson, professor of clinical and molecular psychiatry in the UK, explains that symptoms of inattention as defined in DSM-5 are mostly behavioural – easily distracted, forgetful, trouble completing tasks.
Hyperactive symptoms relate to fidgetiness, restlessness, and being on the go all the time. In terms of impulsivity, Prof Asherson emphasises how people with ADHD have great difficulty waiting in queues, some of whom would put down their shopping and leave the store rather than wait in a line.
In general, the hyperactive and impulsive symptoms decline as people with ADHD become adults. The inattentive symptoms are a greater problem in adults. “The disorder improves to varying degrees in different people. However, ADHD symptoms that are frequent and severe enough to cause impairment are seen in up to 80% of adults who had ADHD as children.”
The DSM also refers to associated features that are often seen in ADHD and can be used to support diagnosis. These include:
- Developmental traits: Mild delays in language, motor, or social development, which are not specific, but often co-occur with ADHD.
- Emotional symptoms: Low frustration tolerance, irritability, mood lability, is very commonly seen in adults with ADHD.
- Educational problems: Even in the absence of a specific learning difficulty, academic or work performance is often impaired.
- Cognitive deficits: May exhibit cognitive problems on tests of attention, executive function, or memory – although tests are not sufficiently sensitive or specific to serve as diagnostic tests.
Prof Asherson explores the concept of the mind wandering excessively. “In ADHD, mind wandering is spontaneous and poorly controlled. Thoughts are ‘on the go’ all the time, jumping from one topic to another, with multiple thoughts at the same time.”
“The types of drugs which reduce ADHD symptoms work on two main neurotransmitter systems – the dopamine system and the noradrenergic system. The stimulants, which give the biggest effect sizes in the treatment of ADHD, target both neurotransmitters. They bring about direct release as well as blocking reuptake (of the neurotransmitter) and have an immediate effect,” he says.
Prof Asherson emphasises that treatment with stimulants should be carefully titrated to each patient, based on individual response.
“In most cases ADHD is a treatable adult mental health condition. Missed or mistaken diagnosis is however common, related to the overlap of symptoms with other disorders, and the limited training and experience of treating ADHD for many adult healthcare professionals,” says Prof Asherson.
Medical treatments such as stimulants are effective and go beyond core ADHD symptoms to include symptoms such as emotional instability, and lead to improved behaviour and function. Effective care pathways need to be developed in both primary and secondary care to recognise and treat Adult ADHD.