Effects of a Single Dose of Bright Light Treatment on Measures of Affective Information Processing
|ClinicalTrials.gov Identifier: NCT03688048|
Recruitment Status : Completed
First Posted : September 27, 2018
Last Update Posted : October 3, 2018
|Condition or disease||Intervention/treatment||Phase|
|Bright Light Treatment Emotion Facial Expression Recognition||Device: Bright light treatment lamp Device: Sham negative ion generator||Not Applicable|
Bright light treatment (BLT) is an efficacious treatment for depressive disorders but the causal mechanisms by which it exerts its clinical effects are largely unknown. According to the cognitive neuropsychological model of antidepressant treatment action, one way by which antidepressant treatments lead to clinical effects is by acutely inducing a relatively increased preferential processing of positive (as compared to negative) emotional stimuli. Whether BLT has the potential to induce such positive biases is not known to date.
Aim of study:
To investigate the influence of single-dose BLT on emotion-related information processing in healthy volunteers.
Using a double-blind, parallel-group design, fifty healthy volunteers (male and female) were randomly allocated to a single session (60 minutes) of treatment with either bright light (10 000 lux) or a credible placebo-sham condition (deactivated negative ion generator). After treatment, all participants underwent testing with the Oxford Emotional Test Battery, an established battery of behavioural tasks that allow to assess emotional information processing in multiple cognitive domains. This battery consists of a facial expression recognition task, an emotional categorization task, an emotional dot probe task, an emotional recall task and an emotional recognition task. Before and after treatment, subjective state was assessed using different questionnaires.
Our working hypothesis, in line with the cognitive neuropsychological model of antidepressant treatment action, is that one-time BLT can induce biases towards positive stimuli in multiple cognitive domains and this bias will be present even in the absence of observable changes in subjective state.
Implications of the study:
This study will show whether a single dose of BLT can influence emotion-related information processing in a similar way as previously observed for antidepressant drugs. If this is the case, then the clinical effects of BLT could be explained through its acute effects on emotional processing. On a broader level, the results of this study will also add to our understanding of any potential effects that acute exposure to bright light (e.g. sunlight) could have on the healthy human mind.
|Study Type :||Interventional (Clinical Trial)|
|Actual Enrollment :||50 participants|
|Intervention Model:||Parallel Assignment|
|Masking:||Triple (Participant, Care Provider, Investigator)|
|Primary Purpose:||Basic Science|
|Official Title:||Can Non-drug Antidepressant Treatments Influence the Way the Human Brain Processes Information?|
|Actual Study Start Date :||February 20, 2017|
|Actual Primary Completion Date :||March 16, 2018|
|Actual Study Completion Date :||March 16, 2018|
Experimental: Bright light treatment
Single-dose bright light treatment (1 hour, 10 000 lux)
Device: Bright light treatment lamp
Exposure to bright white light (1 hour, 10 000 lux)
Placebo Comparator: Sham placebo
Deactivated negative ion generator in conjunction with a plausible cover story
Device: Sham negative ion generator
Placebo treatment with deactivated negative ion generator (1 hour, audible hum, no ions emitted)
- Performance in a facial expression recognition task [ Time Frame: Completed within 2 hours after treatment ]Participants are presented with individual pictures of facial expressions of emotions. Each presented face displays one of six basic emotions (anger, disgust, fear, happiness, sadness, or surprise). Each emotional expression is presented at different levels of intensity which have been created by combining shape and texture features of the two extremes "neutral" (0%) and "full prototypical emotion" (100%) to varying degrees. Examples of neutral facial expressions are presented as well. Participants are instructed to correctly classify each facial expression as angry, disgusted, fearful, happy, sad, surprised or neutral both as quickly and as accurately as possible. Responses are made by pushing one out of seven labelled keys on a response box. Hit rates, false alarm rates, and reaction times for correct classifications are measured separately for each emotion.
- Performance in an emotional categorisation task [ Time Frame: Completed within 2 hours after treatment ]Participants are presented with positive and negative personality descriptors and are asked to classify the valence of each word. These words describe either extremely agreeable/positive characteristics (e.g. "cheerful", "honest", "optimistic") or extremely disagreeable/negative characteristics (e.g. "domineering", "untidy", "hostile") and are presented individually in the centre of the screen. Participants are instructed to imagine themselves overhearing someone describing them with each of the words and to indicate as quickly and accurately as possible whether they would like or dislike to be described with each of the words. Responses are made by pressing a correspondingly labelled key on a button box. Reaction times for correct classifications are measured separately for positive and negative words.
- Performance in an emotional faces dot probe task [ Time Frame: Completed within 2 hours after treatment ]Pictures of positive and negative emotional stimuli (happy and fearful facial expressions) are presented individually together with a matched neutral stimulus (neutral face). On each trial, one stimulus is shown above and the other below a central fixation point. Subsequently, a probe appears behind one of the stimuli and participants have to correctly classify the probe as quickly and as accurately as possible. Stimuli can be masked (i.e. presented very briefly and followed by a jumbled face) or unmasked (i.e. presented for a longer period without a subsequent masking stimulus). Reaction times for correct responses are recorded and vigilance scores are calculated for masked and unmasked positive and negative stimuli by subtracting reaction time data from trials when the probe appeared in the same position as the emotional stimulus (congruent trials) from trials when the probe appeared in the opposite position to the emotional stimulus (incongruent trials).
- Performance in an emotional recall task [ Time Frame: Completed within 2 hours after treatment ]Following a delay period after the emotional categorization task (about 15 min), emotional recall memory is assessed. Participants are asked to recall and write down as many words as possible from the emotional categorization task. Numbers of correctly and incorrectly recalled positive and negative words are measured.
- Performance in an emotional recognition task [ Time Frame: Completed within 2 hours after treatment ]Following the emotional recall task, emotional recognition memory is assessed by presenting participants with the original personality descriptors plus an equal number of matched distractor words (50% positive, 50% negative). Participants are asked to indicate for each word as accurately and as quickly as possible whether they recognise it from the emotional categorization task. Numbers of correctly and incorrectly recognised items as well as reaction times for correct recognitions are measured separately for positive and negative words.
- Change in subjective mood and energy [ Time Frame: Completed within 2 hours after treatment ]Zersen's Befindlichkeits-Skala. Standard questionnaire for subjectively felt mood and energy levels. Total score ranging from 0 to 112. Subscores: Mood (ranging from 0 to 94) and Energy (ranging from 0 to 18). Sum of subscores for mood and energy provide total score. Higher scores represent worse subjective mood and energy.
- Change in positive and negative affect [ Time Frame: Completed within 2 hours after treatment ]Positive and Negative Affect Schedule; standard questionnaire for subjectively felt positive and negative affect. Two scores: (1) Positive score: ranging from 10 to 50 (higher score representing greater extent of positive affect). (2) Negative score: ranging from 10 to 50 (higher score representing greater extent of negative affect).
- Change in subjective anxiety [ Time Frame: Completed within 2 hours after treatment ]State-Trait Anxiety Inventory; standard questionnaire for subjectively felt anxiety. Two scores: (1) State anxiety: ranging from 20 to 80 (higher scores indicating higher state anxiety levels). (2) Trait Anxiety: ranging from 20 to 80 (higher scores indicating higher trait anxiety levels).
- Change in subjective state [ Time Frame: Completed within 2 hours after treatment ]Visual Analogue Scales of different subjective states (anxious, alert, happy, sad, angry, disgusted, afraid); Minimum = 0 mm ("Not at all") , Maximum = 96 mm ("Extremely"); greater scores represent greater extent of felt emotions.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03688048
|University of Oxford|
|Oxford, United Kingdom, OX3 7JZ|