King's College London

The main goals are to see if the supplement increases lithium levels in participants’ blood, how much of it they take, and if they experience any positive or negative side effects.

Participants will be asked to take the supplement daily and come for five visits to the research site at King's Denmark Hill campus in south London, over a six-month period. We will work with them to arrange visitation days that are convenient for them.

Each appointment includes:

• A blood test: This is quick and similar to most blood tests.
• Thinking skills exercises: These are exercises tracking metrics like memory, concentration, planning and reasoning. This takes about 15 minutes.
• Questionnaires: These are conducted with the researcher and cover points like health, daily routines, perceived quality of life, mood and sleep quality.

Lithium is known to improve mood and daily life for people with bipolar disorder and depression and may also help those with dementia, suicidal thoughts and certain viruses. While we are using lower doses in this study, we hope that people might experience a boost in mood, increased cognitive function and other improvements in mental health. Whether these are achieved or not, participants will help us understand if supplementary lithium can benefit people with mood and brain-related conditions.

For each of the five visits, people will receive £24 as a token of appreciation for their participation in the study, as well as some travel expenses.

We are looking for participants with depression. To be eligible, you need to be:

• aged between 18-65 when you enter the study
• experiencing depression
• taking medication for depression, at the same dose for at least six weeks
• willing to try a commercially available lithium supplement
• willing to attend planned study visits.