Table 2.

Differential diagnosis and common comorbidities for anxiety

Child temperament/Emotional regulation development	Behavioural inhibition and low adaptability from a young age are both ‘normal’ variations of temperament and risk factors for anxiety (24,25). Adolescence is a crucial developmental period for emotion regulation but is also associated with increase in affective instability (26).
Environmental adversity	ACEs have a cumulative negative association with mental health outcomes, including anxiety (22,27–30).
School problems	School problems, and learning disabilities specifically, have been strongly associated with later mental health problems, difficult peer and family relationships, and lower quality of life in the longer term (31–33).
ADHD	An estimated 25% of children with ADHD also have anxiety disorders (34), possibly related to effects of ADHD on early development (23).
OCD and tics or TS	Anxiety disorders are often comorbid with OCD (in 26–75% of cases (35)) or tic disorders (in 30% of cases (36)). While these conditions overlap phenomenologically, they appear to have distinct mechanisms (36,37).
ASD	ASD is associated with higher levels of anxiety (38). ASD features, such as sensory over-responsiveness, ­repetitive behaviours (39), and social skill deficits (40), overlap with anxiety symptoms (41).
Eating disorders	High rates of comorbidity exist between eating disorders and anxiety disorders. Anorexia nervosa is ­associated with features of anxiety around body weight or shape perfectionism, and bulimia nervosa is ­associated with low self-esteem (i.e., social anxiety symptoms) and ineffectiveness (i.e., general anxiety symptoms) (42).
Somatic symptom disorders	Somatic symptoms vary widely but include anxiety around becoming ill or functional symptoms, and ­anxious or excessive health-related behaviours (either health promotive or to prevent illness) (43,44).

ACE Adverse childhood experience; ADHD Attention-deficit hyperactivity disorder; ASD Autism spectrum disorder; OCD Obsessive compulsive disorder; TS Tourette syndrome.