Improving working memory performance in brain-injured patients using hypnotic suggestion

Abstract

Working memory impairment is prevalent in brain injured patients across lesion aetiologies and severities. Unfortunately, rehabilitation efforts for this impairment have hitherto yielded small or no effects. Here we show in a randomized actively controlled trial that working memory performance can be effectively restored by suggesting to hypnotized patients that they have regained their pre-injury level of working memory functioning. Following four 1-h sessions, 27 patients had a medium-sized improvement relative to 22 active controls (Bayes factors of 342 and 37.5 on the two aggregate outcome measures) and a very large improvement relative to 19 passive controls (Bayes factor = 1.7 × 1013). This was a long-term effect as revealed by no deterioration following a 6.7 week no-contact period (Bayes factors = 7.1 and 1.3 in favour of no change). To control for participant-specific effects, the active control group was crossed over to the working memory suggestion and showed superior improvement. By the end of the study, both groups reached a performance level at or above the healthy population mean with standardized mean differences between 1.55 and 2.03 relative to the passive control group. We conclude that, if framed correctly, hypnotic suggestion can effectively improve working memory following acquired brain injury. The speed and consistency with which this improvement occurred, indicate that there may be a residual capacity for normal information processing in the injured brain.

Hypnosis for Acquired Brain Injury: Four Patient Cases and Five Testable Predictions

“…However, this literature also has some methodological shortcomings (Lindeløv et al, in review). A randomized controlled study found very large and persistent improvements on working memory (all d > 1.4) following four and eight hours of hypnosis (Lindeløv et al, 2017). A further analysis of interview data from this study found a one-hour reduction in the median need for daily sleep as well as progress on 75% of patientreported outcome measures (Lindeløv et al, in review).…”

“…We have received similar reports from around a third of the participants in Lindeløv et al (2017). Most participants report immediate improvement, but were later surprised to learn that the improvement was much larger than initially felt.…”

“…The hypnotic procedures used in our studies have centered on suggestions that thinking will become automatic, effortless, and reliable after the hypnotherapy (Lindeløv et al, 2017). The protocol encourages the expectation that thinking "just works" and thereby tone down the interoceptive monitoring and its detrimental effects on cognition (Teodoro et al, 2018).…”

“…Her baseline SHSS:C score was 2, i.e., low hypnotizability. She received procedure B in Lindeløv et al, (2017), which consisted of four sessions of hypnosis based on mindfulness suggestions, followed by four sessions of targeted suggestion (see the excerpts above). As with many low-hypnotizables, she reported no experience of trance, worrying that she was unfit for the treatment.…”

“…Autobiographical memories elicited through age-regression in Lindeløv et al (2017) served as a template to which the patient could refer when given suggestions for improvement. It is important to note here that it is ambiguous whether the vividness of hypnotic age-regression reflects a truly accurate recollection, or whether it reflects a larger degree of constructive filling-in (Dywan & Bowers, 1983;Geiselman, Fisher, MacKinnon, & Holland, 1985;Klatzky & Erdelyi, 1985).…”