CCPR: How prevalent is severe irritability and disruptive mood dysregulation disorder (DMDD) in children? How does that compare with genuine rates of pediatric bipolar disorder (PBD)?

Dr. Parry: Roughly 3% of children and adolescents meet criteria for DMDD, introduced in DSM-5 partly to supplant the inaccurate concept of PBD. DMDD’s underlying irritability is dimensional, and the diagnostic threshold is somewhat arbitrary. Genuine bipolar disorder (BD) requires a true manic or hypomanic episode, typically presents in adolescence, and is exceedingly rare in peripubertal children. Anne Duffy and colleagues followed high-risk offspring of parents with BD across six longitudinal studies spanning four countries. Only the Pittsburgh cohort found about half its manic/hypomanic cases had onset by age 12; the other studies found a mean onset of 17.5 years (standard deviation 4.3 years). The Swiss cohort identified 6 hypomanic episodes before age 12, but 2 were equivocal, 4 were trauma-related, and none recurred, so possibly no genuine BD. A later, seventh study from Denmark also found no early cases (www.tinyurl.com/h7pj9swf). PBD was an American phenomenon—not replicated in Australia, the UK, or most of Europe. Chronic irritability is real and clinically significant, but conflating it with BD has caused real harm.

CCPR: What is driving chronic irritability in children, neurobiologically and developmentally?

Dr. Parry: Research on severe mood dysregulation before DMDD identified two core neurobiological signatures: aberrant response to frustrative non-reward (the child overreacts with anger when their wants aren’t met) and an aberrant threat response (the amygdala-based fight-flight-freeze system fires at low threat levels). Our paired amygdalae function as alarms; children with chronically overreactive amygdalae react to ordinary frustration or mild threat as a genuine emergency, before prefrontal regulation can override it. Temperament accounts for roughly 30% of the variance; parenting style accounts for much of the rest—particularly inconsistent reward and punishment, which teaches a child that escalating distress gets their needs met. The most severe presentations occur when a temperamentally reactive child is raised in an inconsistent or high-stress environment (Editor’s note: We also consider how anxiety lowers the threshold of threat responses, along with parental trauma and the family’s relational history).

CCPR: How do family and intergenerational patterns, including epigenetic pathways, contribute to this irritability?

Dr. Parry: Some of what looks like genetic loading is socially modeled behavior transmitted across generations (ie, the parents were never taught to tolerate frustration). Separately, epigenetic mechanisms are real: Early environmental stress can alter gene expression, increasing amygdala reactivity in later generations (Kac E, Front Psychiatry 2026;17:1769422). Cultural context matters too; a Tongan trainee on our Australian inpatient unit once noted she never saw such dysregulated children back home, where extended families shared child-rearing.

CCPR: When you see an irritable child, what is your differential diagnosis?

Dr. Parry: Understanding the person matters more than naming the symptom. As Hippocrates and Menninger urged, always ask: “What is behind the symptom?” Chronic irritability is the final common pathway of several upstream causes; DSM labels describe surface behavior without explaining the currents underneath. In maltreatment and trauma, chronically frightened children become dysregulated—not necessarily a disorder, but a predictable response to an unsafe environment. Neurodevelopmental factors matter too, as undetected learning difficulties can frustrate children when they are pushed beyond their capacity. In autism, sensory overload, difficulty reading social cues, and reduced abstract reasoning drive dysregulation; in ADHD, impulsivity and poor executive function amplify frustration. Pathological demand avoidance, though not an official diagnosis, describes children who default to refusal when unable to meet behavioral expectations. Attachment patterns contribute as well: Disorganized attachment produces dysregulation directly, while ambivalent attachment (an unreliably available parent) teaches the child that escalating protest secures nurture (Bizzi F and Pace CS, Clin Child Psychol Psychiatry 2020;25(4):833–846). These factors can combine to create irritability and dysregulation.

CCPR: How much weight do you give to family systems and socioeconomic context when you’re building out that differential?

Dr. Parry: Our training emphasizes family systems, including socioeconomic pressures, caregiver capacity, and support structures. A stressed single mother who has trouble raising multiple children is not failing at parenting—she is trying to do what humans, a close-knit tribal species akin to other primates, never evolved to do. Socioeconomic stress also affects diet, with nutritional deficiencies and toxicities from ultra-processed foods. The US Department of Health and Human Services is finally addressing this. The child’s environment shapes the child’s neurobiology.

CCPR: Why do you think PBD has come to be diagnosed so widely in the US?

Dr. Parry: My doctoral thesis examined the PBD epidemic, its iatrogenic consequences, and implications for medical ethics. SSRIs were losing patent protection in the early 2000s, while second-generation antipsychotics (SGAs) still had years of patent life remaining. Eli Lilly, whose Prozac patent expired in 2001, held internal meetings documented as the “Zyprexa documents,” now publicly available through the Drug Industry Documents Archive at UCSF. These state that Zyprexa cannot substitute for lost Prozac revenue unless BD maintenance therapy (akin to Depakote) becomes an established indication, and that with too few bipolar patients, the market must expand. Funding flowed to US academic research centers that conceptualized childhood irritability and emotional dysregulation as PBD, generating a lifelong market for “mood stabilizing” SGAs. This sounds extreme, so I encourage readers to view the evidence in chapters 4.2 and 9.4.5, and Appendix D of my thesis (www.tinyurl.com/h7pj9swf).

CCPR: What were the downstream effects on children and families, and why didn’t this epidemic take hold in other countries?

Dr. Parry: PBD shaped an entire era of primarily US child psychiatric practice, led to massive overprescribing of antipsychotics to very young children, and left families with mislabeled children. The phenomenon never gained traction in Australia, the UK, or most of Europe and Asia; the same children existed everywhere, but the commercial infrastructure and the key opinion leaders on PBD were US-centric. US “managed care” precipitated “diagnostic upcoding.” In contrast, the lack of managed care internationally meant less pressure on clinicians to ascribe a serious psychiatric diagnosis to receive reimbursement, and generally more funding for non-pharmacologic therapies.

CCPR: What is “undiagnosis,” and how do you approach it clinically?

Dr. Parry: There’s a useful 2011 paper titled “Undiagnosis: An Important New Role for Psychiatry” (Patfield M, Australas Psychiatry 2011;19(2):107–109). My friend and co-author, the late Dr. Ed Levin, a child psychiatrist, exemplified undiagnosis in two residential units for state care children in Oakland. These children had profound trauma histories; nearly all were diagnosed with PBD alongside ADHD, ODD, and the like. Most were on polypharmacy. Levin introduced trauma-informed care: Staff learned each child’s trauma history and responded to behavioral escalations through mentalizing (asking what might have triggered this child, thinking through how it might connect to their past, and reflecting that back in language the child could hear). Staff also learned to self-regulate before responding to dysregulated children. Over two years, one unit eliminated all psychotropic prescriptions, and the other reduced its psychotropic load by roughly 80%. PBD diagnoses were dropped as children responded (Levin EC, J Am Acad Psychoanal Dyn Psychiatry 2009;37(3):519–538; Parry P, Front Psychiatry 2025;16:1541905).

“Chronic irritability with mood swings does not equal BD. Treating it as such risks both significant harm and a lost opportunity to address what’s driving the presentation.” - Peter Parry, MBBS, PhD, FRANZCP

CCPR: How do you apply that process of undiagnosis in your own clinical practice?

Dr. Parry: First, I ask: “What led to this presentation?” I construct a biopsychosocial formulation, explaining to families that diagnoses describe symptom patterns, not causes, and that descriptions can be revised as understanding improves. My allegorical paper on “cough disorder” illustrates this approach (Parry P, Med J Aust 2009;191(11–12):674–676).

CCPR: How do you talk with young people and families about irritability and dysregulation?

Dr. Parry: I use neurophysiology to help explain DSM labels. Families find it empowering. I start with the amygdala (Greek for “almond,” for its shape) and draw it as the brain’s alarm system. When triggered, the sympathetic “S for stress” system kicks in (fight, flight, freeze, or sometimes fawn—the appeasing, giddy response). I explain that this system evolved to save us when a genuine threat appears, but that in many people (through temperament, or experience, or both) the alarm becomes oversensitive. It fires in response to ordinary frustration, social stress, or a teacher’s criticism, as if reacting to a predator.

CCPR: How do you explain what the child can do about an overactive alarm system?

Dr. Parry: There’s a mechanism, and the young person can understand it and work with it. I draw the parasympathetic nervous system (what I call the “P for peace” system) and explain the vagus nerve: Deep diaphragmatic movements compress it at the gastroesophageal junction and stimulate it. It’s why laughter, sighing, yawning, and sobbing all calm us instinctively. The vagus nerve releases GABA, the brain’s calming neurotransmitter (“natural diazepam”). Diaphragmatic breathing during yoga or meditation works the same way, which is the neurobiology underpinning mindfulness and every self-regulation strategy. I draw the frontal lobes and explain how amygdala hijacking temporarily takes them offline; GABA levels rise with breathing, sleep, safe relationships, time in nature, and post-exercise, letting the frontal lobes come back online to override the alarm and think through problems. This also explains why exposure therapy, sleep, and EMDR works for trauma. A young person who came in expecting another medication leaves with a framework for what’s happening in their brain and what they can do about it.

CCPR: Do you have a bottom line for clinicians when they’re evaluating an irritable child who arrives with a bipolar label?

Dr. Parry: Start over. The family’s experience is real, and the child’s suffering is real. But a diagnosis is a description, not an explanation. Ask what might be behind the symptom: the child’s environment, developmental history, intergenerational patterns, trauma (overt or subtle), learning differences or neurodevelopmental factors, attachment history, socioeconomic and family systems pressures on the caregivers, quality of diet and sleep. Get detail on alleged manic/hypomanic phenomenology. The “fawn” stress response can mimic brief “manic” episodes of ultradian PBD. True mania before mid-adolescence is rare even in genetically high-risk children. Chronic irritability with mood swings does not equal BD. Treating it as such risks significant harm and a lost opportunity to address what’s driving the presentation. The most powerful interventions for these children are trauma-informed care, parent training, helping children understand their neurobiology, and teaching self-regulation, which can also sometimes be done through play therapy. The evidence for these is strong, and they don’t require a bipolar diagnosis to justify them (Editor’s note: Hypnosis can also reduce autonomic arousal, reducing anxiety in youth with medical trauma and, by extension, possibly reducing consequent irritability [Nunns M et al, Psycho-Oncology 2018;27:1889–1899].)

CCPR: Where can clinicians go to learn more?

Dr. Parry: Read our editorial “Getting Diagnosis Right in Child Psychiatry: Lessons From the Pediatric Bipolar Disorder Era,” co-edited with Anne Duffy, Glen Elliott, and Glen Spielmans (Parry P et al, Front Psychiatry 2025;16:1675976).* It accompanies several papers: a Delphi consensus on assessing and treating DMDD, an Australian audit of BD presentations in child and adolescent mental health services, a paper on psychotropic deprescribing for youth with complex needs, and an account of Dr. Ed Levin’s trauma-informed practice.

CCPR: Thank you for your time, Dr. Parry.