Persistent aggressive antisocial behaviour: a promising phenotype

The main ambition for this blog is to provide a decent, science-related and thought-provoking text on forensic psychiatry once a week ("Forensic Friday"). Let's start by the quite basic question: what is the object of forensic psychiatry? What are we working with? During my first decade or so in this peculiar speciality, I often wondered where the focus of my research and clinical work lay. In psychoses, disorders of empathy, psychopathy, personality disorders, autism spectrum disorders, ADHD or even learning disorders? I have always been fascinated by psychiatry as science and loved working with patients. Frankly, I came to forensic psychiatry because there were good research opportunities and plenty of time to spend with each patient, not because I was more interested in criminology than any other occasional reader of Agatha Christie. But somehow, I had to integrate criminal behaviours in the models I worked with. And some years ago, it dawned on me that the real object of our work lies there, hidden in plain sight. Persistent aggressive antisocial behaviour per se is the core phenotype that forensic psychiatry should put center stage, diagnose, understand from the perspectives of etiology, comorbidity and longitudinal development, and learn to prevent and treat.

Persistent aggressive antisocial behaviour indeed seems a highly promising phenotype for research. In its prototypical form, it has an early onset (it may be recognized sometimes between 3 and 5 years of age according to the life-course persistent overt type described by Moffitt), clear genetic liability (about 65% of variance, Burt et al, 2009), high stability into adulthood (a majority still have aggressive antisocial behaviours as adults) and is observable and thus relatively easy to measure. There are interesting etiological hypotheses, such as associations with sex steroids and monoaminergic neurotransmission (e.g. the cerebrospinal fluid ratio between dopamine and serotonin metabolites), hypofunctioning in prefrontal cortex or limbic dysregulation, impulsivity and reactions to drugs. An adolescent-onset subtype is more related to psychosocial factors and has better prognosis.

Its epidemiology is actually well studied. The small subgroup of the population who have the early-onset form of persistent aggressive antisocial behaviour is responsible for the majority of violent crimes (the prevalence will vary across societies, but in modern Sweden, it is as low as 1%, Falk et al 2013). The male:female sex ratio is at least 9:1, maybe even 98:2 for the most aggressive types, and other known co-variates are substance abuse (type-2 alcoholism with early-onset, polysubstance abuse), ADHD and personality disorder. The group of aggressive children also grow up to account for considerable proportions of all psychiatric patients, being over-represented in every diagnostic category in adult psychiatry (Kim-Cohen et al., 2003, one of the most important papers ever published in psychiatry!). Märta Wallinius defended her PhD thesis on aggressive antisocial behaviour in 2012, and it is accessible here.

The Life History of Aggression (LHA) scale was developed by Brown and Goodwin (1982) for research in veterans displaying pathological aggression and self-harm, and has been further validated by Coccaro and co-workers (1997). It contains 11 items describing aggressive, antisocial and self-harming behaviours, each measured by frequency and yielding 0-5 points, thus giving a maximum score of 55, with three subscales for the different types of behaviours included. Scores have a left-skewed (thankfully!) but overall normal distribution, with clear pathology at about +2 standard deviations. The LHA may be used as an expert assessment or as a self-rating. We are currently investigating whether it can also be rated for a specific time-frame, thus measuring also changes in aggressive behaviour.

There are also numerous scales measuring traits related to aggression, such as aggressiveness, anger, impulsivity and so on, but I think that it is important to keep the phenotype definition behavioural, as this will be much more reliable and clinically relevant. In forensic psychiatry, we really cannot be too preoccupied with people's feelings of anger, it is the behaviours that have to change.

Some individuals with persistent aggressive antisocial behaviour may be happy with their behaviour style as it is. In these cases, psychiatry will have little to contribute and it seems best that the penal system is left to do its job undisturbed by medical opinion. But in my experience as a doctor in correctional facilities of different kinds, the vast majority of antisocially aggressive persons are profoundly unhappy about how they constantly screw up their relationships, life plans and dreams. They would be more than happy to test various forms of treatments, be they pharmacological, physical, psychological or educational. And if an intervention would help some tens of percents of affected persons to refrain from half of their future violent crimes, a very significant reduction in societal violence at large might be achieved. With enormous positive health effects at large. 

Why  did it take so long for me too relaize this stunningly simplicit model? And why is this promising phenotype obscured in ratings of controversial diagnoses like psychopathy, conduct disorder or antisocial personality disorder? I think that the answer is simple and a bit humiliating for forensic psychiatry. Persistent aggressive antisocial behaviour is too simple, too obvious, not enough psy-whatever and is difficult to make a big fuss about. There is little money or prestige involved for the expert assigning this diagnosis or from creating diagnostic instruments and specialist training to recognize it. So therefore we have chased illusional diagnoses instead of finding a way to help people stop being aggressive with each other outside of those situations when physical aggression can be pro-social: in sports with clear rules and in tasks contributing to societety's legally regulated monopoly of violence. There is an urgent need for controlled treatment studies with reduced aggressive behaviour as primary end-point, and this should be the primary goal for forensic psychiatric research.