The Effect of PTSD, Dissociation and Interoception on Responses to Touch

Traumatic events are common, with 50% to 70% of people experiencing a traumatic event during their lifetime (PTSD UK,

n.d.). Trauma can result in mental health conditions, including PTSD and dissociative disorders, with 4 in 100 people being diagnosed with PTSD (Mind, 2020). Dissociation is a common symptom and sub-category of PTSD, with 14.4% of PTSD

patients experiencing dissociative symptoms (Stein et al., 2013). Dissociation can also occur independently of PTSD, with the most common types of dissociation being depersonalisation and derealisation. Dissociative disorders have a lifetime

prevalence rate of 9% to 13% (Langeland et al., 2020). This links to interoception, as dissociation relates to less awareness

of the body. It is important to study these conditions as they can impact daily life and wellbeing. This area of research can lead to the development of treatments, ranging from talking therapies to social support in the community, with recent research focusing on touch-based therapies in PTSD (Reeve, Black and Huang 2020).

Touch is an important area of study, as it is experienced in a variety of social situations. It has been argued that touch is

essential for wellbeing, with childhood trauma often causing touch aversion in adulthood (Maier et al., 2020). Early research focusing on the importance of touch in childhood was by Harlow and Zimmerman (1959), who found that baby rhesus monkeys preferred touch from a cloth mother, rather than a wire mother, regardless of whether the mother offered milk.

This study highlighted the importance of touch and comfort in infants, as monkeys appeared less distressed when they could seek comfort from the cloth mother. Later research, which expanded on Harlow and Zimmermanâs (1959) study, by

Harlow, Dodsworth & Harlow (1965), demonstrated the impact of parental touch during infanthood on wellbeing. Monkeys

were raised in isolation, without touch or comfort, leading to aggression and an inability to regulate emotions, which can be predicted in humans who experience childhood trauma. This highlights the importance of touch in supporting wellbeing

throughout development and adulthood. In the proposed research, Study 1 will include questionnaire measures to determine levels of PTSD, dissociation and

interoception. Furthermore, I will use the Touch Experience and Attitudes Questionnaire (TEAQ; Trotter et al., 2018) as a

comparison measure, to determine if touch attitudes can be predicted by PTSD, dissociation, or interoception scores. Study 2

will involve participants with high scores on the questionnaires from Study 1, as well as participants with low scores as controls. This study will measure neural responses to touch using electroencephalogram (EEG), event-related potentials (ERP) and heartbeat evoked potentials (HEP), looking at responses when participants receive touch on the hand and

vicarious touch on the hand and abdomen. This will determine whether levels of PTSD, dissociation or interoception will affect neural responses to touch and whether this differs between touch on the hand and vicarious touch on the hand and abdomen. The use of HEP will determine whether neural responses can be associated with heart rate (HR). Study 3 will

expand on Study 2, including expected and unexpected touch, to determine whether unexpected touch will affect touch

responses more than expected touch. Advanced quantitative methods will be used to analyse multiple dependent and independent variables. I will use

multivariate multiple regression to determine whether there are relationships between the variables, also adding moderators to this model in Studies 2 and 3. This will create impact as related literature has never combined PTSD, dissociation,

interoception and touch responses. Therefore, this research will increase the understanding of PTSD and dissociation, as well as their link to interoception and neural responses to touch.