Ketosis Impact on Signs & Symptoms of Schizophrenia and Bipolar disorderS (KISSeS)

Pilot Study on Ketosis Impact on Signs and Symptoms of Schizophrenia and Bipolar Disorders

The goal of this clinical trial is to learn if a ketone drink can improve signs and symptoms of patients with a schizophrenia-spectrum disorder (SSD), or a bipolar-spectrum disorder (BD).

The main questions it aims to answer are:

Does a ketone drink improve information processing in patients with SSD/BD?

Other questions it aims to answer are:

Does a ketone drink improve cognitive functioning in patients with SSD/BD? Does a ketone drink improve metabolism and inflammation in patients with SSD/BD? Does a ketone drink affect circadian rhythm in patients with SSD/BD?

Research will compare the effects of the ketone drink with that of an isocaloric carbohydrate drink in the same patients ('cross-over').

Participants will:

1. drink a ketone drink and (after a wash-out period) an isocaloric control drink (randomized order); after each drink:

   • EEG/EMG to determine information-processing parameters (PPI and P300)
   • cognitive tests
   • visual analog scale of mood, energy levels, ability to focus
   • indirect calorimetry to determine use of energy substrate
   • blood draws

2. for 5 consecutive days:

   • wear a continuous glucose monitor (CGM)
   • wear a non-invasive passive sweat biomarker sensor (EnLiSense device)
   • register a diet and nicotine diary
   • saliva sampling (max. 5x/day)

Study Overview

• Status: Completed
• Conditions: Bipolar and Related Disorders; Psychosis; Schizophrenia and Related Disorders; Depressive Episode; Manic Episode
• Intervention / Treatment: Dietary supplement: (R)-3-hydroxybutyl (R)-3-hydroxybutyrate); Other: Maltodextrin, Fructose, Pectin, Sodium alginate, Sodium chloride

• Study Type: Interventional
• Enrollment (Actual): 28
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Netherlands
  • North Holland
    • Amsterdam, North Holland, Netherlands, 1105 AZ
      • Amsterdam UMC, dept. Psychiatry

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients with a first-episode psychosis (underlying schizophrenia-spectrum disorder), or patients with a (hypo)manic or depressive episode (underlying bipolar disorder)
• Age >= 18 years old
• Receiving standard care (including antipsychotic and mood stabilizing medication)
• Mentally competent to give informed consent:

Exclusion Criteria:

• Substance use as cause of psychosis or (hypo)mania
• Substance use (other than nicotine) in the week prior to study onset
• Intellectual disability
• Diabetes mellitus (type 1 or type 2)
• Metabolic disease impacting ketone metabolism (NB: these are rare disorders diagnosed during childhood)
• Liver disease
• Kidney disease
• Cardiovascular disease
• Pregnancy
• Breastfeeding

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: dGK; 1x50 g dGK ketone drink	Dietary supplement: (R)-3-hydroxybutyl (R)-3-hydroxybutyrate); 1x50g ingestion of pure dGK; Other Names: delta G Ketones (dGK)
Active Comparator: isocaloric carb control; 1x isocaloric carbohydrate control drink	Other: Maltodextrin, Fructose, Pectin, Sodium alginate, Sodium chloride; Isocaloric carbohydrate control (active control); Other Names: Maurten Drink Mix 160

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Prepulse Inhibition (PPI) - change dGK vs isocaloric control	PPI: an event-related potential (ERP) representing information processing (known to be disrupted in schizophrenia and bipolar disorder). The PPI task is an auditory paradigm featuring a total of 10 trials split evenly into two conditions: prepulse (PP) and non-prepulse (NP) in blocks. Startle pulses are 100dB at 40 ms, which is shown to provide significant startle visible in EEG126. Prepulse stimuli are 70 dB and 50 ms in duration, presented 50ms prior to the startle pulse. There is a 12 to 18 (avg: 15 s) interstimulus interval. All stimuli are white-noise blips. A calibrated apparatus is used to present the stimuli. Total estimated time is 20 min.	measured 45 minutes (Tmax) after ingestion of intervention 1 (dGK) and 45 minuts after ingestion of intervention 2 (isocaloric carb control)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
P300 Event Related Potential (change dGK vs isocaloric control)	The P300 task consists of 160 stimuli in the oddball paradigm and requires the subjects to press a button on detection of the rare target (32/160). The common nontarget stimuli are 500 Hz, 100 ms duration. The rare target stimuli are 700 Hz. Both are 100 ms duration at 80 dB with variable interstimulus interval of 1.2 to 1.5 s. Preceded by 10 practice trials. This task has minimal burden and requires about 10 minutes.	measured 65-75 minutes after ingestion of intervention 1 (dGK) and 75 minutes after ingestion of intervention 2 (isocaloric carb control); NB: directly after PPI.
Cognitive test: 15 Word Test (15WT) - change dGK vs isocaloric control	15WT is a measure of verbal/episodic memory. The 15WT consists of 15 words, which have to be learned during three trials. After every trial the respondent is asked to recall as many words as possible. After a distraction period of 20 minutes, the respondent is asked to name the words they have learned before, again. Immediate recall after 1 test: maximum 15 words (minimum 0) Immediate recall after 3 test: maximum 45 words (minimum 0). Retention score after 20 minutes: percentage of correctly remembered words in the delayed recall-trial, relative to the number of words correctly remembered in the third immediate recall-trial; percentage of correctly remembered words in the delayed recall-trial, relative to the maximum score in the immediate recall-trials Higher 15WT scores indicate better verbal/episodic memory, lower scores the opposite.	measured 75-85 minutes after ingestion of intervention 1 (dGK) and 75 minutes after ingestion of intervention 2 (isocaloric carb control); NB: directly after P300.
Cognitive test: Trail Making Test A (TMT-A) - change dGK vs isocaloric control	TMT-A is a measure of (visual) attention. TMT-A outcome is the duration of time required to finalize test (including the time needed for the correction of errors prompted by the examiner), with a maximum of 5 minutes. The average TMT-A score in healthy adults is 29 seconds; a deficient score is greater than 78 seconds. Higher scores on TMT-A indicate worse (visual) attention.	measured 75-85 minutes after ingestion of intervention 1 (dGK) and 75 minutes after ingestion of intervention 2 (isocaloric carb control); NB: directly after P300.
Cognitive test: Trail-Making Test B (TMT-B) - (change dGK vs isocaloric control)	TMT-B is a measure of (frontal) executive functioning. TMT-B outcome is the duration of time required to finalize test (including the time needed for the correction of errors prompted by the examiner), with a maximum of 5 minutes. Average TMT-B score is 75 seconds; a deficient score is greater than 273 seconds. Higher scores on TMT-B indicate worse (frontal) executive functioning.	measured 75-85 minutes after ingestion of intervention 1 (dGK) and 75 minutes after ingestion of intervention 2 (isocaloric carb control); NB: directly after TMT-A.
Cognitive test: Digit Span Test (DST) (change dGK vs isocaloric control)	DST is a measure for working memory. DST outcome is the maximum number of sequential digits correctly reproduced. In average healthy adults, the digit span is around 7 +/- 2. Minimum score is 0, maximum score is 9. Lower DST score indicate worse working memory.	measured 75-85 minutes after ingestion of intervention 1 (dGK) and 75 minutes after ingestion of intervention 2 (isocaloric carb control); NB: directly after TMT-B.
Patient experience outcome on Mood, energy level, focus (change dGK vs isocaloric control)	visual analog scale (VAS) is used with a scale of 0 to 10 to measure patient-experiences effects of the interventions on their mood (0=extremely depression, 10 = extremely happy/euforic), energy level (0=completely exhauster, 10= extremely energetic) and ability to focus (0=completely unable to focus, 10=perfect focus).	measured circa 120 minutes after ingestion of intervention 1 (dGK) and circa 120 minutes after ingestion of intervention 2 (isocaloric carb control)
Immune function: blood markers (change dGK vs isocaloric control)	sequential blood sampling through intravenous line: concentration (pg/ml) of inflammatory biomarkers relevant for immune function: IL-1b; IL-6; IL-8; IL-10; TNF-a; IFN-g; hsCRP Comparison between dGK and isocaloric control at the same time points (see below).	first blood sample before ingestion (dGK or isocaloric control) (T0), then every 20 minutes in first hour after ingestion; afterwards every 30 minutes (max. 3 hours)
Immune function: blood RNA markers (change dGK vs isocaloric control)	RNA expression analysis (immune panel nCounter, Nanostring) in whole blood: comparison dGK vs isocaloric control only at T0 plus 90 minutes.	first blood sample before ingestion (dGK or isocaloric control) (T0), next at T0+90 minutes
Immune function: passive sweat IL-6 (change dGK vs isocaloric control)	continuous measurement of IL-6 (pg/ml) in passive sweat (EnLiSense device)	Full 5 days of the study
Immune function: passive sweat TNF-a (change dGK vs isocaloric control)	continuous measurement of TNF-a (pg/ml)in passive sweat (EnLiSense device)	Full 5 days of study
Metabolic function: Indirect Calorimetry (change dGK vs isocaloric control)	Resting energy expenditure (REE) is measured by gaseous exchange (indirect calorimetry). Oxygen consumption and CO2 production are measured during 20 minutes using a ventilated hood system (Q-NRG, Cosmed). Subjects lie flat on their backs and breathe into a canopy for 20 minutes. REE and Respiratory Quotient (RQ) are calculated with these measurements. The RQ represents the ratio of CO2 exhaled to the amount of 02 consumed by the individual and represents whole body substrate oxidation (glucose, fat and protein oxidation).	circa 90-120 minutes after ingestion of intervention 1 (dGK) and intervention 2 (isocaloric control); directly after finalizing cognitive tests.
Metabolic function: blood biomarkers - change dGK vs isocaloric control	Sequential blood sampling through intravenous line, to determine the plasma and serum concentrations of: Glucose; Ketones; acylcarnitine profile; growth hormone (GH); superoxide dismutase (SOD); gluthione S-transferase (GST); soluble intercellular adhesion molecule 1 (sICAM1) Comparison between dGK and isocaloric control at the same time points (see below).	first blood sample before ingestion (both dGK and isocaloric control) (T0), then every 20 minutes in first hour after ingestion; afterwards every 30 minutes (max. 3 hours)
Metabolic function: continuous glucose monitor (CGM) - change dGK vs isocaloric control	continuous glucose monitor (CGM; Abbott Libre Sense); continuous concentration in mM.	Full 5 days of the study.
Circadian rhythm: passive sweat cortisol (change dGK vs isocaloric control)	continuous measurement of cortisol (pg/ml) in passive sweat (EnLiSense device)	Full 5 days of study
Circadian rhythm: passive sweat melatonin (change dGK vs isocaloric control)	continuous measurement of melatonin (pg/ml) in passive sweat (EnLiSense device)	Full 5 days of study

Collaborators and Investigators

• Sponsor: Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA)
• Collaborators: University of Alberta; The University of Texas at Dallas; Parnassia Groep; EnLiSense
• Investigators: Principal Investigator: Karin Huizer, MD/PhD, Parnassia Groep

Publications and helpful links

General Publications

• Dielemans DA, Yurtkap Y, van der Pluijm M, Soeters MR, Oranje B, Smit DJ, Ziermans T, van Tricht MJ, Muthukumar S, Prasad S, van der Mieden van Opmeer RL, Dekeyster E, Kamperman AM, Dyck JR, Rosema BS, Hoekstra R, Kupka RW, de Haan L, van Beveren NJ, Huizer K. The Effect of Exogenous Ketones on Signs and Symptoms of Schizophrenia Spectrum and Bipolar Disorders: Study Protocol for a Triple-Blind, Randomized, Controlled Crossover Pilot Study. Curr Dev Nutr. 2025 May 24;9(6):107480. doi: 10.1016/j.cdnut.2025.107480. eCollection 2025 Jun.

Study record dates

Study Major Dates

• Study Start (Actual): December 1, 2024
• Primary Completion (Actual): April 17, 2026
• Study Completion (Actual): April 17, 2026

Study Registration Dates

• First Submitted: May 8, 2024
• First Submitted That Met QC Criteria: May 17, 2024
• First Posted (Actual): May 23, 2024

Study Record Updates

• Last Update Posted (Actual): April 27, 2026
• Last Update Submitted That Met QC Criteria: April 22, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Schizophrenia Spectrum and Other Psychotic Disorders; Mental Disorders; Neurobehavioral Manifestations; Mood Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Mania; Bipolar and Related Disorders; Schizophrenia; Psychotic Disorders; Carbohydrates; Inorganic Chemicals; Chlorine Compounds; Polymers; Macromolecular Substances; Polysaccharides; Sugars; Plant Extracts; Plant Preparations; Biological Products; Complex Mixtures; Biopolymers; Sodium Compounds; Hexoses; Monosaccharides; Chlorides; Hydrochloric Acid; Ketoses; maltodextrin; Sodium Chloride; Alginates; Fructose; (R)-3-hydroxybutyl (R)-3-hydroxybutyrate; Pectins
• Other Study ID Numbers: NL83836.018.23; 2024.0100 (Other Identifier: METC AUMC)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No