Investigating Interventions for Affect and CognitionThree Randomized Controlled Trials
Investigating Interventions for Affect and Cognition
Three Randomized Controlled Trials
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DissertationDate of Exam
29.08.2025Date of Publication
25.09.2025Advisor
Ettinger, UlrichCo-Referee
Wagner, MichaelMetadata
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Abstract
Improving mental health and cognition is highly desirable due to the important impact they have on individual quality of life and societal functioning. Making mental health and cognitive enhancement interventions accessible, affordable, and low-effort is crucial to ensuring that they reach as many people as possible. There are many open questions in this area. Some of them are: How can we improve the effectiveness of light therapy against seasonal affective disorder? Does "more light" help more? Does supplementing creatine improve cognition? How effective are self-help apps against anxiety? How do different psychotherapeutic exercises compare to each other?
This thesis addresses these questions by presenting results from three studies designed to test accessible interventions for mental health and cognitive improvement. All studies were randomised, controlled, and double-blind or partially blind, and followed the CONSORT reporting guidelines and Open Science principles. Data were analysed using frequentist (standard and robust) statistics as well as Bayesian statistics.
Study 1, a feasibility study, found that BRight, whole-ROom, All-Day (BROAD) light therapy against seasonal affective disorder was feasible and that the effectiveness of the therapy correlated positively with illuminance at eye level. Study 2 was somewhat inconclusive, with no significant effect of creatine on cognition (frequentist statistics), weak evidence for a small effect, and strong evidence against a large effect (Bayesian statistics). Study 3 found that the 12 exercises of the Mind Ease self-help app against anxiety, based on cognitive behavioural therapy, mindfulness, and acceptance and commitment therapy, had large effects on immediate anxiety levels. Mindfulness exercises had particularly large effects. Overall, a broad picture of interventions to improve mental health and cognition is provided and best practices in methods and statistics shared by the three studies are discussed.
This thesis addresses these questions by presenting results from three studies designed to test accessible interventions for mental health and cognitive improvement. All studies were randomised, controlled, and double-blind or partially blind, and followed the CONSORT reporting guidelines and Open Science principles. Data were analysed using frequentist (standard and robust) statistics as well as Bayesian statistics.
Study 1, a feasibility study, found that BRight, whole-ROom, All-Day (BROAD) light therapy against seasonal affective disorder was feasible and that the effectiveness of the therapy correlated positively with illuminance at eye level. Study 2 was somewhat inconclusive, with no significant effect of creatine on cognition (frequentist statistics), weak evidence for a small effect, and strong evidence against a large effect (Bayesian statistics). Study 3 found that the 12 exercises of the Mind Ease self-help app against anxiety, based on cognitive behavioural therapy, mindfulness, and acceptance and commitment therapy, had large effects on immediate anxiety levels. Mindfulness exercises had particularly large effects. Overall, a broad picture of interventions to improve mental health and cognition is provided and best practices in methods and statistics shared by the three studies are discussed.
Subjects
Affekt, Kognition, affect, cognition
Classification (DDC)
150 PsychologieRelated Publications
https://doi.org/10.1002/da.23281https://doi.org/10.1186/s12916-023-03146-5
https://doi.org/10.1155/da/5586831
Supplementary Research Data
https://osf.io/hc6nx/Sandkühler, Julia Fabienne: Investigating Interventions for Affect and Cognition : Three Randomized Controlled Trials. - Bonn, 2025. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5-84796
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5-84796
@phdthesis{handle:20.500.11811/13461,
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5-84796,
author = {{Julia Fabienne Sandkühler}},
title = {Investigating Interventions for Affect and Cognition : Three Randomized Controlled Trials},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2025,
month = sep,
note = {Improving mental health and cognition is highly desirable due to the important impact they have on individual quality of life and societal functioning. Making mental health and cognitive enhancement interventions accessible, affordable, and low-effort is crucial to ensuring that they reach as many people as possible. There are many open questions in this area. Some of them are: How can we improve the effectiveness of light therapy against seasonal affective disorder? Does "more light" help more? Does supplementing creatine improve cognition? How effective are self-help apps against anxiety? How do different psychotherapeutic exercises compare to each other?
This thesis addresses these questions by presenting results from three studies designed to test accessible interventions for mental health and cognitive improvement. All studies were randomised, controlled, and double-blind or partially blind, and followed the CONSORT reporting guidelines and Open Science principles. Data were analysed using frequentist (standard and robust) statistics as well as Bayesian statistics.
Study 1, a feasibility study, found that BRight, whole-ROom, All-Day (BROAD) light therapy against seasonal affective disorder was feasible and that the effectiveness of the therapy correlated positively with illuminance at eye level. Study 2 was somewhat inconclusive, with no significant effect of creatine on cognition (frequentist statistics), weak evidence for a small effect, and strong evidence against a large effect (Bayesian statistics). Study 3 found that the 12 exercises of the Mind Ease self-help app against anxiety, based on cognitive behavioural therapy, mindfulness, and acceptance and commitment therapy, had large effects on immediate anxiety levels. Mindfulness exercises had particularly large effects. Overall, a broad picture of interventions to improve mental health and cognition is provided and best practices in methods and statistics shared by the three studies are discussed.
},
url = {https://hdl.handle.net/20.500.11811/13461}
}
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5-84796,
author = {{Julia Fabienne Sandkühler}},
title = {Investigating Interventions for Affect and Cognition : Three Randomized Controlled Trials},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2025,
month = sep,
note = {Improving mental health and cognition is highly desirable due to the important impact they have on individual quality of life and societal functioning. Making mental health and cognitive enhancement interventions accessible, affordable, and low-effort is crucial to ensuring that they reach as many people as possible. There are many open questions in this area. Some of them are: How can we improve the effectiveness of light therapy against seasonal affective disorder? Does "more light" help more? Does supplementing creatine improve cognition? How effective are self-help apps against anxiety? How do different psychotherapeutic exercises compare to each other?
This thesis addresses these questions by presenting results from three studies designed to test accessible interventions for mental health and cognitive improvement. All studies were randomised, controlled, and double-blind or partially blind, and followed the CONSORT reporting guidelines and Open Science principles. Data were analysed using frequentist (standard and robust) statistics as well as Bayesian statistics.
Study 1, a feasibility study, found that BRight, whole-ROom, All-Day (BROAD) light therapy against seasonal affective disorder was feasible and that the effectiveness of the therapy correlated positively with illuminance at eye level. Study 2 was somewhat inconclusive, with no significant effect of creatine on cognition (frequentist statistics), weak evidence for a small effect, and strong evidence against a large effect (Bayesian statistics). Study 3 found that the 12 exercises of the Mind Ease self-help app against anxiety, based on cognitive behavioural therapy, mindfulness, and acceptance and commitment therapy, had large effects on immediate anxiety levels. Mindfulness exercises had particularly large effects. Overall, a broad picture of interventions to improve mental health and cognition is provided and best practices in methods and statistics shared by the three studies are discussed.
},
url = {https://hdl.handle.net/20.500.11811/13461}
}
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