9 Child and adolescent psychiatry9.6 Aetiological influences
9.6 Aetiological influences in child and adolescent psychiatry
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Written by Resident Doctor Committee · Published
Principles of risk
Risk factors shift probabilities rather than fixing a diagnosis, and a child's characteristics shape how others respond to them.
Equifinality means different pathways reach the same outcome, as when depression follows bullying, loss or illness.
Multifinality means one exposure leads to different outcomes, including no disorder.
Rutter showed that psychiatric risk rises when family adversities cluster, such as conflict, low social status, overcrowding and disrupted care.
Genes and environment
Gene-environment interaction means an environmental effect differs by genotype.
Caspi's Dunedin studies linked maltreatment to antisocial outcomes more strongly in men with low-activity MAOA, and stress to depression in 5-HTTLPR short-allele carriers, which large collaborative analyses did not support.
Gene-environment correlation means heritable characteristics go with differences in the environments people meet.
Type | Mechanism | Example |
|---|---|---|
Passive | Parents supply the genes and much of the environment | Family liability to anxiety alongside anxious caregiving |
Evocative | The child's traits shape how others respond | A hard-to-soothe baby shapes caregiving |
Active | The child selects environments, more so with autonomy | A sociable child seeks out peers |
Parenting styles
Baumrind described three styles by their balance of control and warmth, and Maccoby and Martin added the uninvolved style.
Style | Control and warmth | Child tends to be |
|---|---|---|
Authoritative | High control and high warmth, with limits explained and the child's view heard | Confident, sociable, self-reliant |
Authoritarian | High control and low warmth, with fixed rules and punishment for questioning | Obedient but withdrawn, unhappy, reliant on adults for decisions |
Permissive | High warmth with almost no demands | Immature, impulsive, poorly self-controlled, with early alcohol and drug use later |
Uninvolved | Low control and low warmth | Poorest outcomes: low self-esteem, school failure, truancy, delinquency |
Authoritative and authoritarian parents both control firmly, but only authoritative parents add warmth and explain their rules.
Risk factors for specific disorders
Disorder | Risk factor | Detail |
|---|---|---|
Primary enuresis | Family history | About 44% risk with one affected parent and 77% with both; linkage to 13q, 12q and 22q |
Down syndrome | A parent carrying a Robertsonian translocation | Substantial recurrence risk, unlike free trisomy, mosaicism or de novo rearrangements |
Autism | Advanced paternal age | One of the most consistent demographic risks, probably through more new sperm mutations |
Childhood-onset conduct disorder | Harsh, inconsistent parental discipline | Patterson's coercion cycle rewards escalating defiance |
Externalising problems | A brother or sister with oppositional defiant disorder or conduct disorder | A probabilistic risk, not a certainty |
Reactive attachment disorder | Grossly inadequate early care | Institutional rearing or repeated change of carer, as the Bucharest Early Intervention Project showed |
Delayed empathy and theory of mind in deaf children follow from restricted early access to fluent shared language.
Deaf children of hearing, non-signing parents are the most delayed, while deaf children of signing deaf parents develop close to hearing peers.
The Camberwell Family Interview rates expressed emotion (criticism, hostility and over-involvement) from the content and tone of a relative's recorded speech.
Early deprivation
The English and Romanian Adoptees study found substantial recovery after adoption from institutional deprivation, with raised risk mainly after more than about six months, not a two-year cutoff.
A sensitive period is a time when development is especially open to influence, and a critical period is a tighter window; neither makes later help pointless.
Formulation
Factor | Example |
|---|---|
Predisposing | Genetic liability, earlier adversity |
Precipitating | Loss, illness, school transition |
Perpetuating | Continuing bullying, conflict, avoidance |
Protective | Reliable care, school connection |
The same factor can change role with timing: parental depression may be a long-standing vulnerability or a recent trigger.