Changes in Delay Discounting, Time estimation ability and the role of Trauma in Addicted Patients during Initial treatment

It has been shown that impulsivity is closely linked with addictive behavior
(Lee, Hoppenbrouwers, & Franken, 2019). A commonly used behavioral measure of
impulsive decision making is delay discounting which has shown to be associated
with addiction and other externalizing behavior (e.g. Bickel, Odum, & Madden,
1999). The basis of delay discounting was the notion that drug dependence can
be understood through the lens of behavioral economics; via availability (cost)
of the drug, substitutes (other drugs, or non-drug activities) and further the
discounting of delayed rewards resulting in *loss of control* (Bickel et al.,
1998).

One of the recurring hypotheses is that delay discounting as such may be due to
aberrations in the subjective perception of time (e.g. Gallistel & Gibbon,
2000; Takahashi, 2005, 2006; Namboodiri, Mihalas, & Shuler, 2014b). A recent
review (Paasche, Weibel, Wittman, & Lallane, 2019) has specifically proposed a
relationship between time perception and impulsivity in understanding the
psychopathology of addiction. Research on changes in delay discounting in
association with treatment of addiction is scarce.

Trauma & addiction are strongly related. A recent study found that 45,8% of
addicted inpatients had met criteria for lifetime PTSD and 25% met criteria for
current PTSD (Kok et al., 2015). A total of 95,8% of patients had suffered at
least one trauma and the earliest trauma occurred at a mean of 11,3 years old.
Given the association between addiction and delay discounting, one could make
the assumption of a relationship between trauma and delay discounting. Research
on the relationship between trauma and delay discounting is limited; in BPD,
childhood trauma is predictive of delay discounting (Barker et al., 2015) and
it has been shown that early traumatized individuals show steeper delay
discounting (Simmen-Janevska, Forstmeier, Krammer, & Maercker, 2015). Research
on relationship between trauma, delay discounting and addiction is scarce; a
recent study found that delay discounting, severity of trauma symptoms and
substance use were positively related (Morris et al., 2020)

Generally, problems with delay discounting are defined in the form of
steepness, representing a devaluation of future consequences. A far less
studied phenomenon in relation to delay discounting is anhedonia, or diminished
interest in pleasurable activities and the inability to experience positive
emotions. Anhedonia is an important feature of Post-Traumatic Stress Disorder
(PTSD; American Psychiatry Association, 2013). Experimental evidence on the
association between anhedonia and delay discounting is limited and
inconclusive. Furthermore, impaired time distortion is a known aspect of
dissociative responses to a traumatic experience (e.g. Bryant, 2007) but this
has not been extensively researched.

In summary, there are indications that addiction, delay discounting, time
estimation and trauma are associated, but the nature of these relationships is
in need of further research. The primary goal of the present study is to assess
whether delay discounting and time estimation ability improves in patients from
pre-treatment to post-treatment. Furthermore, we hypothesize to find a
reduction in delay discounting as an indicator of treatment success. As part of
this, time estimation ability will be assessed. We expect to find an
association between improved delay discounting and improvements in time
estimation. In summary, we aim to establish the extent of the associations
between treatment success, delay discounting and improvements in time
estimation ability. Finally, we expect to find associations between
PTSD-severity, delay discounting and time estimation ability.

The aim of this study is to obtain answers to the following main questions:
1. Are delay discounting, time estimation and PTSD influenced by treatment?
2. Do patients differ from healthy controls in delay discounting and/or time
estimation ability?

In addition, the study will address the following secondary questions:
3. Which individual psychological variables at intake are associated with
abstinence at end of treatment?
4. Is delay discounting (at intake) a valid predictor of treatment-drop out?
5. How is Trauma associated with delay discounting?

The design of the study is observational. Patients will receive treatment
exactly as per normal protocols; additional information will be gathered on:
- patients addiction severity
- IQ
- measures of self-assessed impulsivity
- trauma
- time estimation ability

The present study will be conducted at the outpatient clinic of Antes, where
substance dependent participants will be monitored during their first phase of
treatment. This first phase of treatment on average lasts 6 months and is
primarily aimed at discontinuing a patients* substance use and relapse
prevention. Phase 1 treatment is individualized, focused on abstinence.
Treatment is likely to include Cognitive Behavioral Therapy; however,
alternatives may be more suitable. Some patients will receive medication to
support abstinence.

Measurement will be repeated at the end of phase 1 treatment (after 6 months),
in addition to abstinence status (self-report).
Abstinence self-report will be validated by 4 weekly urinalysis tests in the
final weeks of treatment.

Burden and risks of patients' participation are limited.