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Neurolaw and Genetics

17 January 2013

 John Rumbold

“Genetics may yet threaten privacy, kill autonomy, make society homogeneous and gut the concept of human nature. But neuroscience could do all of these things first.” The Economist 2002.

Neurolaw is the field of study concerning the application of neuroscience to the legal process. There are a number of research centres and organizations working on neurolaw and the related topic of neuroethics:

MacArthur Foundation Research Network on Law and Neuroscience (Vanderbilt University)

The Initiative on Neuroscience and the Law (Baylor College of Medicine)

Moral Cognition, Neuroethics and Neurolaw Research Cluster of the Center for Agency, Values and Ethics (Macquarie University)

Stanford Center for Law & the Biosciences

The Oxford Centre for Neuroethics

Australian Law and Neuroscience Project

There are a number of blogs on the topic:

Neulaw Blog (Baylor)

Neuroethics & Law Blog (Brooklyn Law School)

Law and Neuroscience Blog (Vanderbilt)

Nicole Vincent (Macquarie University)

Law & Biosciences Blog (Stanford University)

A frequent area of research is the assessment of criminal responsibility by anatomical and functional neuro-imaging and, less commonly, genetics. Can genetics help the legal system, and if so, in what way? I hope to answer these questions over this series of online articles.

Genetics and parasomnias

My PhD research at Keele concerns expert evidence about parasomnias and the legal defence of automatism. I first became interested in this area after hearing about the cause celebré of Kenneth Parks (see below). Parasomnias are “unpleasant or undesirable behavioral or experiential phenomena that occur predominantly or exclusively during the sleep period” (Mahowald, M & Cramer Bornemann, M. 2010). Sleepwalking is the commonest parasomnia and the one most often used to support the defence of automatism.

The defence of automatism applies to anyone who was acting like an automaton – that is, involuntarily. This is the case for sleepwalkers, who are effectively acting in their sleep. They are generally not held responsible for their actions.

Sleepwalking

Sleepwalking


The difficulty for the courts is that unlike most of the other parasomnias, sleepwalking is essentially a clinical diagnosis. There are usually no specific findings on sleep studies and so accounts of sleepwalking episodes from family and friends will be crucial. A family history of sleep disorders will be also be strong supporting evidence – the stronger the family history, the worse the sleepwalking is

likely to be. This reliance on history has led to unwarranted allegations at trial that “anyone can claim to be a sleepwalker”.

Twin studies have demonstrated that there is a substantial genetic contribution to sleepwalking; 80% of adult sleepwalking in males and 36% of adult sleepwalking in females (Hublin et al, 1997).

There has been one genetic locus identified recently at chromosome 20q12-q13.13 for an autosomal dominant trait with reduced penetrance (Licis et al, 2011), and sleepwalking is also linked to certain HLA types. It is not known what the mode of inheritance of sleepwalking is generally – it has been hypothesized as multi-factorial or autosomal recessive with incomplete penetrance. Sleepwalking and night terrors seem to have a common genetic predisposition (Kales et al, 1980). The amount of slow wave sleep (known to affect the probability of parasomnia) is influenced by a specific gene, the retinoid acid receptor beta encoding gene or Rarb (Maret et al, 2005). Once genes for sleepwalking have been identified, they might help to identify people at risk for serious violence during sleepwalking through particular genotypes – however, recurrence of serious harm is almost non-existent which suggests that there is no particular phenotype associated with violence.

Kenneth Parks

Kenneth Parks

One of the most notorious sleepwalking cases occurred in Toronto in 1987, Kenneth Parks drove 23 km to his in-laws’ house, negotiating at least one set of traffic lights, and killed his mother-in-law and seriously injured his father-in-law. He then drove to the police station, telling them he had killed somebody. He had a family history of sleepwalking, adult enuresis, nightmares and sleeptalking. He had been under great stress with debts accumulated due to his gambling addiction. His behaviour is considered by many sleep experts to be inconsistent with sleepwalking

.

Scott Falater

Scott Falater

Another infamous case involved Scott Falater, who in 1999 stabbed his wife 44 times then drowned her in the pool in Phoenix, Arizona. He had an extensive family history of sleep disorders and had been a sleepwalker from childhood. He had exhibited a violent reaction during sleepwalking on a previous occasion. His family pedigree is shown below:

Family Pedigree

Family Pedigree

(figure reproduced from ‘Sleepwalking Violence:  A Sleep Disorder, a Legal Dilemma, and a Psychological Challenge’, Am J Psychiatry 2004;161:1149-1158, by kind permission of Rosalind Cartwright )

Scott Falater is ‘Mr A’, with a history of sleepwalking, enuresis, sleep talking and bruxism. Many members of his extended family had sleep disorders, either sleepwalking or disorders related to sleepwalking.

Like Parks, he was under considerable stress and sleep deprived. 9He was convicted after one sleep specialist described his actions as attempts to cover up evidence. He was spared the death penalty and his son still works for his exoneration.

Another parasomnia that is associated with harmful behaviour is night terrors. This is probably what Brian Thomas suffered from when he strangled his wife in their campervan in Aberporth in 2009. He was acquitted on the direction of the judge after both experts agreed he had been asleep.

In summary, genetics may have a role in supporting the diagnosis of sleepwalking. The benefit in the forensic setting may be minimal, where the main issue is not the diagnosis of sleepwalking as such but the determination of whether or not the episode in question was sleepwalking. As Mark Mahowald put it, “[Proving that] someone is a sleepwalker… is only Part 1 of a two-part question. The second question is whether he was sleepwalking on the night of the murder. Only God can answer that”(Stryker, 1999). Corroborative evidence tends to help the defence more as juries probably start from a position of scepticism (for good reason). “Objective” evidence will probably make juries more likely to acquit. I would argue on this basis that genetic evidence will not necessarily improve jury decision-making.

Bibliography:

Hublin, C; Kaprio, J; Partinen, M; Heikkila, K; Koskenvuo, M. (1997) Prevalence and genetics of sleepwalking: A population-based twin study. Neurology 48: 177-181.

Kales, A; Soldatos, CR; Bixler, EO; Ladda, RL; Charney, DS; Weber, G; Schweitzer. PK. (1980) Hereditary factors in sleepwalking and night terrors. British Journal of Psychiatry 137:111-18.

Licis, AK; Desruisseau, DM; Yamada, KA; Duntley, SP; Gurnett, CA. (2011) Novel genetic findings in an extended family pedigree with sleepwalking. Neurology 76(1): 49-52.

Mahowald, MW; Cramer Bornemann, MA. (2010) ‘Chapter 74 NREM Sleep-Arousal Parasomnias’ in Kryger, M., T. Roth and W. Dement (eds), ‘Principles and Practice of Sleep Medicine’ (5th edn Saunders, Philadelphia.

Maret, S; Franken, P; Dauvilliers, Y; Ghyselinck, NB; Chambon, P; Tafti, M. (2005) Retinoic acid signaling affects cortical synchrony during sleep. Science 310: 111–113

Stryker, J (1999). ‘Sleepstabbing:The strange science of sleep behavior and one verdict: Guilty!’. url: http://www.salon.com/1999/07/08/sleepwalking/ accessed on Mar 29th 2011.

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