Other Psychiatric Conditions In Child Psychiatry

• Hong Kong data suggest child psychiatric disorders affect ~10-15% of children/adolescents.
• High academic pressure culture → disproportionate rates of anxiety (especially performance anxiety, test anxiety) and youth depression.
• Rising referral rates to child psychiatric services in Hong Kong, with anxiety and ADHD being the most common referral diagnoses.
• Selective mutism may be under-recognised in bilingual (Cantonese–English) environments where language switching can mask symptoms.
• Youth suicide is a significant public health concern in HK, often linked to untreated depression.

These monoamine-releasing neurones belong to the reticular activating system (RAS), which regulates global behavioural states — sleep-wake cycle, appetite, motor activity, emotional processing, learning and memory ^[1]. Deficiency in these neurotransmitters accounts for the broad clinical picture of depression (sleep disturbance, appetite changes, psychomotor changes, mood symptoms, cognitive impairment).

The hypothalamic-pituitary-adrenal (HPA) axis is the master stress response system:

1. Hypothalamus releases CRH →
2. Anterior pituitary releases ACTH →
3. Adrenal cortex releases cortisol →
4. Cortisol feeds back to hypothalamus and hippocampus (negative feedback)

In children exposed to chronic stress/adversity:

• The HPA axis becomes dysregulated (blunted or exaggerated cortisol response).
• Chronic cortisol elevation → hippocampal atrophy → impaired negative feedback → more cortisol → vicious cycle.
• This is the neurobiological basis for why early life adversities (abuse, neglect, parental separation) are such powerful risk factors for both anxiety and depression ^[1][3].

Child psychiatric conditions follow a biopsychosocial model where genetics load the gun, environment pulls the trigger, and developmental stage determines the expression.

• Definition: consistent failure to speak in specific social situations (e.g., school) where speaking is expected, despite speaking in other situations (e.g., home)
• "Mutism" → "mutus" (Latin) = silent; "selective" = only in certain contexts
• Not due to lack of language knowledge or comfort with the spoken language
• Now classified under anxiety disorders in DSM-5 (previously under disorders of social functioning in ICD-10)

Pathophysiology:

• Conceptualised as an extreme form of social anxiety — the child is so anxious about social evaluation that speech is completely inhibited
• The amygdala-based fear response "shuts down" the speech production areas (Broca's area, supplementary motor area) in the presence of perceived social threat
• Often associated with behavioural inhibition temperament
• Genetics: family aggregation with social anxiety disorder
• Environmental: may be exacerbated by bilingual environments, immigration, traumatic experiences

• Definition (ICD-10 F93.3): Abnormally intense negative feelings (jealousy, hostility, aggression) toward a sibling, arising after the birth of a younger sibling, that are persistent and clearly out of the norm ^[1]
• Usually manifests as regression (bed-wetting, baby-talk), temper tantrums, aggression toward the new sibling, and attention-seeking behaviour
• Pathophysiology: Loss of exclusive parental attention is perceived as a threat to the child's attachment security → anxiety and anger → externalised as rivalry behaviours
• The severity depends on: child's age, temperament, quality of prior attachment, parental handling of the transition

• PTSD can occur in children and resembles the adult counterpart ^[1], but with important developmental modifications
• Children may not articulate re-experiencing symptoms verbally — instead they show:
  • Repetitive play with trauma themes (the child "acts out" the trauma)
  • Trauma-specific nightmares (which may become generalised frightening dreams)
  • Regression (loss of previously acquired skills, e.g., toilet training)
  • Behavioural re-enactment (acting out the trauma in daily behaviour)

Pathophysiology (shared with adults):

• Traumatic event → overwhelming of normal stress response → failure of fear extinction ^[5]
• Amygdala hyperactivation + hippocampal suppression → emotional memory is "burned in" without proper contextualisation → re-experiencing
• HPA axis dysregulation → chronic hyperarousal
• Prefrontal hypoactivity → failure of top-down emotional regulation → inability to suppress fear response

This is a critical concept — the neural substrate of anxiety is the same across ages, but the content changes with developmental stage ^[1]:

PTSD can occur in children and resembles the adult counterpart ^[1], but the developmental modifications listed above are critical for diagnosis.

These must always be considered first because anxiety symptoms (tachycardia, tremor, sweating, restlessness, poor concentration) are non-specific — they can be produced by any condition that activates the sympathetic nervous system or mimics its effects.

First-principles reasoning: The sympathetic nervous system activation that underlies anxiety symptoms is a final common pathway. Any condition that increases sympathetic tone — whether endogenous (thyrotoxicosis, phaeo) or exogenous (stimulants, caffeine) — will produce the same autonomic symptoms. You cannot diagnose a psychiatric anxiety disorder until you have excluded these organic mimics.

Within the anxiety disorder family, the differentials are important because management differs:

Key principle from the lecture: Panic attacks tend to be expected in other anxiety disorders (e.g., triggered by social situations in social phobia, by separation in separation anxiety disorder) ^[7]. Only in panic disorder are there recurrent unexpected (uncued) panic attacks with persistent worry about further attacks.

DSM-5 Criteria in Detail (309.21 / F93.0):

A. Developmentally inappropriate and excessive fear or anxiety concerning separation from those to whom the individual is attached, as evidenced by ≥ 3 of the following:

1. Recurrent excessive distress when anticipating or experiencing separation from home or attachment figures
2. Persistent and excessive worry about losing attachment figures or about possible harm to them
3. Persistent and excessive worry about an untoward event causing separation (e.g., getting lost, being kidnapped)
4. Persistent reluctance or refusal to go out/away from home (school, work) because of fear of separation
5. Persistent and excessive fear of or reluctance about being alone or without attachment figures at home or other settings
6. Persistent reluctance or refusal to sleep away from home or without being near an attachment figure
7. Repeated nightmares involving the theme of separation
8. Repeated complaints of physical symptoms (headaches, stomach aches, nausea, vomiting) when separation from attachment figures occurs or is anticipated

B. Duration ≥ 4 weeks in children/adolescents, ≥ 6 months in adults C. Clinically significant distress or impairment D. Not better explained by another mental disorder

Why ≥ 3 of 8? Because separation anxiety manifests across multiple domains — cognitive (worry), behavioural (avoidance/refusal), somatic (physical symptoms), and affective (distress). Requiring ≥ 3 ensures the diagnosis captures a pervasive pattern rather than an isolated symptom.

DSM-5 Criteria (300.23 / F40.10):

A. Marked fear or anxiety about ≥ 1 social situations in which the individual is exposed to possible scrutiny by others (e.g., social interactions, being observed, performing in front of others)

• In children: the anxiety must occur in peer settings and not just during interactions with adults B. The individual fears that they will act in a way or show anxiety symptoms that will be negatively evaluated C. The social situations almost always provoke fear or anxiety
• In children: may be expressed by crying, tantrums, freezing, clinging, shrinking, or failing to speak D. The social situations are avoided or endured with intense fear/anxiety E. The fear/anxiety is out of proportion to the actual threat posed by the social situation F. Duration ≥ 6 months G. Clinically significant distress or impairment H. Not attributable to substance or another medical condition I. Not better explained by another mental disorder J. If another medical condition (e.g., stuttering, obesity) is present, the fear/anxiety is clearly unrelated or excessive

Specify if: Performance only (fear is restricted to speaking or performing in public)

Key child-specific modification: In adults, the person must recognise the fear is excessive. In children, this requirement is dropped — children often lack the metacognitive capacity to evaluate their own fear as "excessive."

DSM-5 Criteria (312.23 / F94.0):

A. Consistent failure to speak in specific social situations in which there is an expectation for speaking (e.g., at school), despite speaking in other situations B. The disturbance interferes with educational/occupational achievement or social communication C. Duration ≥ 1 month (not limited to the first month of school) D. The failure to speak is not attributable to a lack of knowledge of, or comfort with, the spoken language E. The disturbance is not better explained by a communication disorder and does not occur exclusively during ASD, schizophrenia, or other psychotic disorder

Why the "first month of school" exclusion? Because many children are shy and quiet when entering a new environment. This is a normal adjustment. The 1-month rule ensures we are not pathologising normal adaptation.

DSM-5 Criteria (313.89 / F94.1):

A. A consistent pattern of inhibited, emotionally withdrawn behaviour toward adult caregivers, manifested by both:

1. The child rarely or minimally seeks comfort when distressed
2. The child rarely or minimally responds to comfort when distressed B. A persistent social and emotional disturbance characterised by ≥ 2 of:
3. Minimal social and emotional responsiveness to others
4. Limited positive affect
5. Episodes of unexplained irritability, sadness, or fearfulness even during nonthreatening interactions C. The child has experienced a pattern of extremes of insufficient care, as evidenced by ≥ 1 of:
6. Social neglect or deprivation (persistent lack of basic emotional needs for comfort, stimulation, affection)
7. Repeated changes of primary caregivers that limit opportunity to form stable attachments
8. Rearing in unusual settings that limit opportunities to form selective attachments (e.g., institutions) D. The care in Criterion C is presumed to be responsible for the disturbed behaviour in Criterion A E. The child does not meet criteria for ASD F. The disturbance is evident before age 5 years G. The child has a developmental age of ≥ 9 months

Why exclude ASD? Because both RAD and ASD involve poor social responsiveness — but the mechanism is completely different. In RAD, the social circuit is intact but suppressed due to environmental deprivation. In ASD, the social circuit is neurodevelopmentally impaired. The clinical clue: RAD children show improvement when placed in a nurturing environment; ASD children do not dramatically change.

DSM-5 Criteria (313.89 / F94.2):

A. A pattern of behaviour in which the child actively approaches and interacts with unfamiliar adults, exhibiting ≥ 2 of:

1. Reduced or absent reticence in approaching unfamiliar adults
2. Overly familiar verbal or physical behaviour
3. Diminished or absent checking back with adult caregiver after venturing away
4. Willingness to go off with an unfamiliar adult with minimal or no hesitation B. Behaviours in A are not limited to impulsivity (as in ADHD) but include socially disinhibited behaviour C. History of extremes of insufficient care (same as RAD Criterion C) D. The care in C is presumed responsible for the behaviour in A E. The child has a developmental age of ≥ 9 months

Why distinguish from ADHD impulsivity? An ADHD child might impulsively approach a stranger, but this is part of general behavioural disinhibition — they are also impulsive in non-social contexts (blurting out answers, can't wait their turn). DSED children are specifically and selectively indiscriminate in their social approach — their impulsivity is social attachment-specific.

The DSM-5 criteria for PTSD in children ≥ 6 years are essentially the same as for adults ^[9]:

A. Exposure to actual or threatened death, serious injury, or sexual violence via direct experience, witnessing, learning about it happening to a close family member/friend, or repeated exposure to aversive details

B. Intrusion symptoms (≥ 1): recurrent intrusive memories, distressing dreams, dissociative reactions (flashbacks), psychological distress at exposure to cues, marked physiological reactions to cues

C. Avoidance (≥ 1): avoidance of distressing memories/thoughts/feelings; avoidance of external reminders

D. Negative alterations in cognitions and mood (≥ 2): inability to remember important aspects of trauma, persistent negative beliefs about self/world, persistent distorted cognitions about cause/consequences, persistent negative emotional state, diminished interest in activities, detachment, persistent inability to experience positive emotions ^[9]

E. Marked alterations in arousal and reactivity (≥ 2): irritable behaviour/angry outbursts, reckless/self-destructive behaviour, hypervigilance, exaggerated startle, concentration problems, sleep disturbance ^[9]

F. Duration > 1 month G. Clinically significant distress or functional impairment H. Not attributable to substance or medical condition ^[9]

This is a separate criteria set in DSM-5, tailored for young children who cannot articulate internal experiences:

• Criterion B (Intrusion): same, but traumatic dreams may not have recognisable content (generalised frightening dreams); re-enactment may occur in play
• Criteria C and D are combined into one cluster requiring only 1 symptom (instead of requiring both avoidance AND negative cognitions separately) — because young children have limited avoidance capacity and cannot report cognitive distortions
• Criterion E (Arousal): same as adults
• Duration > 1 month, functional impairment, not substance-related

Why a lower threshold for young children? Young children have limited verbal capacity and metacognitive ability. A 3-year-old cannot tell you "I have distorted cognitions about the cause of the trauma" or "I feel emotionally numb." The preschool criteria rely more on observable behaviours (play re-enactment, regression) and set a lower symptom count because the same underlying disorder expresses through fewer observable channels.

DSM-5 criteria for Major Depressive Disorder ^[14]:

A. ≥ 5 of the following symptoms present during the same 2-week period, representing a change from previous functioning; at least one must be (1) or (2):

1. Depressed mood most of the day, nearly every day — in children and adolescents, can be irritable mood
2. Markedly diminished interest or pleasure in all or almost all activities
3. Significant weight loss/gain or decrease/increase in appetite — in children, failure to make expected weight gains
4. Insomnia or hypersomnia
5. Psychomotor agitation or retardation (observable, not just subjective)
6. Fatigue or loss of energy
7. Feelings of worthlessness or excessive/inappropriate guilt
8. Diminished ability to think/concentrate or indecisiveness
9. Recurrent thoughts of death, suicidal ideation, or suicide attempt

B. Symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning ^[14]

C. The episode is not attributable to the physiological effects of a substance or to another medical condition ^[14]

D. Not better explained by schizoaffective disorder, schizophrenia, schizophreniform disorder, delusional disorder, or other psychotic disorders ^[14]

E. Absence of previous manic or hypomanic episode ^[14]

Why can irritable mood substitute for depressed mood in children? As discussed in the pathophysiology section, the developing prefrontal cortex cannot modulate negative affect into the articulate experience of "sadness" — instead, it manifests as low frustration tolerance and irritability. The DSM-5 explicitly accommodates this developmental reality.

Varied clinical presentation — the lecture emphasises ^[14]:

• In some younger people, the first obvious sign may be loss of interest in friends, decline in school performance, self-injury or bulimia or drug use in a previously stable adolescent
• In some older people, symptoms may mimic dementia — deterioration of cognitive functioning and self-care
• In some tragic cases, symptoms may be masked to others until the person is found dead by suicide

ICD-10 Criteria:

• Some degree of emotional disturbance usually following the birth of an immediately younger sibling
• If marked in degree and associated with abnormalities in social interactions, should be coded
• The sibling rivalry disorder may be characterized by marked jealousy, rivalry, hostility toward the sibling
• May manifest as behavioural regression, temper tantrums, dysphoria, sleep disturbance, attention-seeking
• Must be persistent and clearly out of norm ^[1]
• No DSM-5 equivalent (not included as a separate diagnostic entity)

Since adjustment disorder is an important differential in child psychiatry:

DSM-5 Criteria: A. Development of emotional or behavioural symptoms in response to an identifiable stressor, occurring within 3 months of the onset of the stressor B. Symptoms are clinically significant as evidenced by either:

1. Marked distress out of proportion to the severity of the stressor
2. Significant impairment in social, occupational, or other functioning C. Does not meet criteria for another mental disorder and is not merely an exacerbation of a pre-existing disorder D. Symptoms do not represent normal bereavement E. Once the stressor has terminated, symptoms do not persist for more than an additional 6 months

Specify subtypes: with depressed mood, with anxiety, with mixed anxiety and depressed mood, with disturbance of conduct, with mixed disturbance of emotions and conduct, unspecified

Why does accommodation reinforce anxiety? If a parent allows the child to stay home every time they feel anxious about school, the child learns: "Anxiety → avoidance → relief." This is negative reinforcement (the behaviour of avoidance is strengthened by removal of the aversive stimulus). Psychoeducation teaches parents to support the child through the anxiety rather than helping them escape it.

CBT is the main psychological treatment for anxiety disorders ^[1][15][16].

Why CBT works in children (first-principles reasoning):

CBT targets the cognitive-behavioural cycle that maintains psychiatric symptoms:

1. Cognitive component: Identifies and challenges distorted thinking patterns (e.g., catastrophising: "If mum doesn't pick me up, something terrible will happen"; overgeneralisation: "I failed one test, so I'll fail everything")
2. Behavioural component: Gradually exposes the child to feared situations (exposure therapy) to break the avoidance-reinforcement cycle

The developing brain is highly plastic — children can learn new cognitive patterns more readily than adults. CBT essentially "retrains" the prefrontal cortex to regulate the amygdala more effectively.

Specific CBT techniques used in child psychiatry:

Trauma-focused CBT is considered first-line treatment for PTSD ^[9][16].

EMDR (Eye Movement Desensitisation and Reprocessing) is also effective for PTSD ^[9]:

• Involves: patient imagines a scene from the trauma, focuses on accompanying cognition and arousal, while the therapist moves two fingers across the patient's visual field and instructs the patient to track the fingers ^[9]
• Sequence repeated until anxiety decreases, with patient instructed to generate a more adaptive thought ^[9]
• Most studies show it is efficacious in PTSD, superior to other less-specific psychotherapy ^[9]
• Mechanism debated — may work through dual-attention (the eye movements tax working memory, reducing the vividness and emotionality of the trauma memory during reprocessing)

1. Pharmacotherapy is rarely first-line — it is reserved for moderate-severe cases, cases with significant functional impairment, or when psychotherapy alone has failed ^[1]
2. "Start low, go slow" — but children may ultimately need weight-adjusted doses similar to or higher than adult doses due to faster hepatic metabolism
3. Informed consent — from parents AND age-appropriate assent from the child
4. Close monitoring — especially in the first weeks, for suicidality (SSRIs) and side effects
5. Time-limited trials — reassess the need for medication periodically; many childhood conditions are self-limiting

"SSRI" → Selective Serotonin Reuptake Inhibitor → selectively blocks the serotonin transporter (SERT) at the presynaptic terminal → ↑synaptic 5-HT availability → downstream receptor changes → therapeutic effect ^[15].

Specific SSRI Agents:

Side Effects of SSRIs in Children:

Why combine SSRI + CBT for severe anxiety? The landmark CAMS (Child/Adolescent Anxiety Multimodal Study) trial showed that combination treatment (sertraline + CBT) was superior to either alone, with ~81% response rate vs ~60% for CBT alone or ~55% for sertraline alone. The SSRI lowers the baseline anxiety level, making the child more able to engage in exposure-based CBT.

Approach (adapted from NICE guidelines) ^[15]:

Prophylaxis ^[15]:

• First episode → continue antidepressants for ≥ 6-9 months at dose that induces remission
• ≥ 2 episodes with significant functional impairment → continue antidepressants for ≥ 2 years

Treatment ^[9][16]:

Treatment ^[16]:

• 40-60% treatment response overall ^[16]
• 1st-line: Behaviour therapy (exposure and response prevention, ERP) + serotonergic antidepressants (SSRI, usually at higher doses than for depression) ^[16]
• Augmentation: adjunctive antipsychotics (e.g., risperidone, aripiprazole) for partial responders ^[16]
• Refractory: psychosurgery (rarely) ^[16] — e.g., anterior cingulotomy or deep brain stimulation; reserved for the most severe, treatment-resistant cases with significant disability

Why higher SSRI doses for OCD? OCD is thought to involve a deeper serotonergic dysfunction in the cortico-striato-thalamo-cortical (CSTC) circuit. The higher dose may be needed to achieve sufficient SERT blockade in these specific circuits to interrupt the obsessional loop.