Attention drifting, restlessness and rapid responses can occur together for reasons other than ADHD. An assessment therefore also considers when the difficulties began, what tends to accompany them and how they vary over time.

• Anxiety and persistent stress: Worry may draw attention away from the task at hand. Physical tension can make it harder to sit still or relax. Uncertainty may prompt quick questions or responses.

• Depression or prolonged exhaustion: Starting tasks, following steps and concentrating can become more difficult. Exhaustion may also contribute to irritability or impatience.

• Insufficient sleep or a sleep disorder: Poor sleep can increase forgetfulness and attention-related errors. Fidgeting, repeatedly getting up or responding more quickly may also occur.

• Certain mood states: Activity and talkativeness may suddenly increase compared with the person’s usual pattern. The need for sleep may decrease. The person might start several plans, and risk-taking can become more frequent.

• Trauma and heightened alertness: Attention may shift towards possible threats. An unexpected sound or comment can trigger an immediate defensive response. From the outside, this may look like inattention or impulsivity.

• Medication effects, caffeine and substance use: A recently introduced medication, a change in dosage, increased caffeine intake or substance use can contribute to restlessness, talkativeness or fluctuations in attention.

• Physical or neurological factors: Some health conditions can affect attention, activity levels and behavioural regulation. A sudden change or involuntary movement may require separate investigation.

No single sign reliably distinguishes these factors from ADHD, and some may coexist with it. An assessment therefore considers co-occurring conditions, physical health, developmental history and information from more than one setting.