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NCT Number: NCT07750925

Examining Lithium's Mechanism in Bipolar Disorder

The primary objective of the current study is to examine the acute effect of lithium on the visual and non-visual responses to light in a sample of healthy participants. Our experiments will investigate the effects of lithium on light sensitivity at the level of the retina as well as central visual and non-visual pathways.

Our primary hypothesis is that the administration of lithium to healthy volunteers will reduce the magnitude of a range of non-visual responses to light including melatonin suppression, alertness, performance, mood and electrophysiology in a manner that is dependent of the amount of lithium in the brain. To better understand the postulated effects of lithium on light sensitivity and to examine its relationship at the level of the retina, we will assess the visual and non-visual responses to light, as well as the distribution of lithium in the brain using a non-invasive imaging technique. In addition to that, we also aim to examine the impact of both lithium and light on a molecular level through whole blood transcriptome sequencing.

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Key information

Conditions

Healthy Bipolar Eye Diseases Nervous System Diseases Neurologic Manifestations Pathological Conditions, Signs and Symptoms Photophobia Sensation Disorders Signs and Symptoms Vision Disorders

Age range

18 year–40 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Aged between 18 and 40 years old
  • Fluent in English (both spoken and written)
  • Sleep duration between 6.5 and 9 hours daily
  • Have a regular normal sleep schedule with bedtime (weekdays) between 21:30 and 01:00.
  • BMI between 18 and 28kg/m2
  • Currently enrolled and registered with a general practitioner
  • Female participants only: should use effective contraception or refrain from engaging in sexual activity that could result in pregnancy during participation in the study.

Exclusion criteria

  • History of psychiatric or neurological disorders
  • First-degree family history of psychosis or severe mood disorder
  • Current or past suicidal ideation or self-harm
  • Current, chronic infections or diseases.
  • Life-threatening allergies, specifically a nut allergy.
  • Known visual disorders e.g., colour blindness, glaucoma, cataracts, diabetic retinopathy.
  • Known medical conditions that could affect the conduct of the study including
  • sleep disorders
  • cancer
  • diabetes
  • anaemia
  • epilepsy
  • psoriasis
  • thyroid disorders
  • kidney disease
  • severe eczema
  • anemia
  • migraines
  • Taking any long-term or regular medications other than oral contraceptives (e.g., antidepressants, diuretics (water-tablets), pain killers or anti-inflammatory drugs (such as ibuprofen) or medications for high blood pressure).
  • Have donated blood in the past 1 month
  • Regular or recent recreational drug use
  • Chronic alcohol addiction/misuse
  • Known contraindication to magnetic resonance imaging such as pacemaker or metal implants, recent surgery, severe claustrophobia and/or recent head or neck tattoos.
  • A current smoker (including use of cigarettes, vapes, and/or cigars).
  • Planning to travel across time zones at any point in time during the conduct of the study or have travelled across time zones within 1 month prior to enrolment.
  • Currently work night shifts
  • Been a shift worker in the past 3 months.
  • Current enrolment in any other interventional studies
  • Enrolment in any other interventional studies in the 1 month prior to the start of participation in this study

Treatment and study plan

Lithium carbonate (Priadel)

Drug

Oral lithium carbonate 600 mg daily for 7 days prior to the second laboratory assessment (and for both days while in the laboratory)

Controlled light exposure

Other

Participants undergo 90-minute dim light (<1 lux) and light exposure (100-850 lux) conditions during laboratory assessments to evaluate visual and non-visual responses to light.

Primary outcomes

  1. Plasma melatonin change in response to light stimulation

    Time frame: Measured during the 90-minute light exposure session after 7 days of lithium treatment and after 7 days in the no-lithium condition (days 9-11 and 19-21).

    Difference in plasma melatonin suppression following light exposure between the no-lithium and lithium conditions.

  2. Brain lithium signal intensity measured by 7Li-MRI

    Time frame: Measured once following 9 days of lithium carbonate administration (Day 21)

    Quantification of brain lithium signal intensity using 7Li magnetic resonance imaging following 9 days of lithium carbonate administration in healthy participants.

Secondary outcomes

  1. Difference in colour vision post-light exposure between lithium and no-lithium conditions

    Time frame: Measured immediately following the 90-minute light exposure session after 7 days in the lithium condition and after 7 days in the no-lithium condition (days 9-11 and 19-21)

    To determine differences in the Cambridge Colour Test (CCT) for changes in colour vision between the lithium and placebo groups post light exposure

  2. Waking EEG Measures

    Time frame: EEG recordings will occur pre, post and throughout the 90-minute light exposure during days 9-11 and 19-21. EEG recordings will be conducted hourly when the participant is awake in the laboratory.

    Hourly waking electroencephalography (EEG) data collected when the participant is awake in the lab will be compared between the lithium and no-lithium conditions. EEG data collected pre, post and during the 90-minute light exposure will be compared between the lithium and no-lithium conditions.

  3. Pittsburgh Sleep Quality Index

    Time frame: Measured at screening and following 7 days of lithium administration (screening stage 2 and day 19)

    Difference in Pittsburgh Sleep Quality Index total score between the lithium and no-lithium conditions in healthy participants. The global score on ranges from 0 to 21, where higher scores represent poorer sleep quality.

  4. Munich Chronotype Questionnaire

    Time frame: Measured at screening and following 7 days of lithium administration (screening Stage 2 and Day 19)

    Difference in Munich Chronotype Questionnaire(MCTQ) measures between the lithium and no-lithium conditions in healthy participants. Total score on the MCTQ ranges from 16 to 86, with 16 to 41 being the eveningness type, 42 to 58 being the intermediate type, and 59 to 86 being the morningness type.

  5. General Health Questionnaire - 12

    Time frame: Measured at screening and following 7 days of lithium administration (screening stage 2 and day 19).

    Difference in General Health Questionnaire-12 (GHQ-12) total score between the lithium and no-lithium conditions in healthy participants. The responses to all items are summed up to a total score of 0 to 36, with higher scores indicating poorer health status.

  6. Karolinska Sleepiness Scale

    Time frame: Measured during and immediately following the 90-minute light exposure session after 7 days in the no-lithium condition and after 7 days of lithium administration (days 9-11 and 19-21).

    Difference in Karolinska Sleepiness Scale scores following light exposure between the lithium and no-lithium conditions in healthy participants. The scores range from 1 (extremely alert) to 9 (very sleepy, fighting sleep), with higher scores indicating increased sleepiness.

  7. Psychomotor Vigilance Test

    Time frame: Measured immediately following the 90-minute light exposure session after 7 days in the no-lithium condition and after 7 days of lithium administration. (And hourly while awake in the laboratory) (Days 9-11 and 19-21)

    Difference in Psychomotor Vigilance Test (PVT) pre and post light exposure between the lithium and no-lithium conditions in healthy participants will be compared. Mean reaction time (RT), lapses (RT > 500ms), and false starts (responses before stimulus or <100 ms) will be analysed. A higher mean RT and a greater number of lapses on the task represent poorer alertness and performance.

  8. Morningness-Eveningness Questionnaire

    Time frame: Measured at screening and following 7 days of lithium administration (screening stage 2 and day 19).

    This task is a measure of chronotype. Difference in Morningness-Eveningness Questionnaire total score between the lithium and no-lithium conditions in healthy participants. The score on this task ranges from 16 to 86. A score of 16-41 represents an evening person. A score of 59-86 represents a morning person and a score of 42 to 58 represents an intermediate person.

  9. Reading the Mind in the Eyes

    Time frame: This task will be implemented during the laboratory segment of the lithium and no-lithium condition. The task will be implemented hourly when the participant is awake in the laboratory. (Days 9-11 and Days 19-21)

    This task will help assess a person's ability to interpret the emotional state of others based solely on images of their eyes, essentially measuring their "Theory of Mind" (ToM) - the capacity to understand and attribute thoughts and feelings to others.

  10. Karolinska Drowsiness Test

    Time frame: Days 9-11 and 19-21, hourly while awake and before/after the light exposure segments.

    Drowsiness will be assessed with EEG data when the Karolinska Drowsiness Test is implemented. The Alpha and Theta power density, the Alpha Attenuation Coefficient (AAC), and the Alpha-Theta power differences will be assessed and analysed.

Study contacts

Contact information is provided by the study sponsor or research team.

Nayantara Santhi

CONTACT

[email protected]

0191 227 4055

Saranea Ganesan

CONTACT

[email protected]

+447587590262

Sponsors and collaborators

Lead sponsor

Northumbria University

Other

Collaborators

  • Newcastle University
  • Northumberland, Tyne and Wear NHS Foundation Trust

Registry information

Official study title

Investigating the Acute Effect of Lithium on Visual and Non-visual Responses to Light in Healthy Individuals

Acronym: HELIOS-BD 2

Important dates

Study start
2026
Primary completion
2028
Study completion
2029
First posted
Aug 6, 2026
Registry last updated
Aug 6, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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