Glossary

A charity registered with the Australian Charities and Not-for-profits Commission. Registration is public, and anyone can search the register. Charities are encouraged to make profits. Those profits can only be used for the purpose of the Charity and not distributed to members. Donations of $2 or more are tax deductible in Australia.

Distress and stress symptoms that begin soon after a traumatic event and last from three days to one month. If they continue longer, a doctor may consider PTSD.

Emotional or behavioural symptoms that develop within about three months of an identifiable stressor, such as a job loss or relationship end, and are more than expected.

The study of the causes of a disease or condition. Causes may be genetic, infectious, environmental or unknown.

The national body that regulates registered health practitioners in Australia, such as doctors, nurses and pharmacists. It also sets rules for health advertising.

A compound the body makes that works in mitochondrial energy production and as an antioxidant.

The building blocks of proteins. Some, such as tryptophan and tyrosine, are used to make neurotransmitters.

Reduced ability to feel pleasure or interest in things that used to be enjoyable. It is a symptom seen in several conditions, particularly depression.

Antidepressants: see Psychotropic medicines (antidepressants and others)

A general term to describe a substance that may limit damage from a redox process which is out of balance.

Anxiety is considered a normal response to stress. Generalised anxiety disorder is diagnosed when worry is excessive, hard to control and present on more days than not, for at least six months, with symptoms such as restlessness, tiredness, poor concentration, tension or poor sleep.

The molecule cells use as fuel. It carries energy to wherever work needs to be done.

A pattern of inattention and/or hyperactivity and impulsivity that interferes with daily life and begins in childhood. It continues into adulthood for many people.

A neurodevelopmental difference affecting social communication and interaction and involving repetitive behaviours or strong specific interests. Autism is not a mental illness, though autistic people may also experience mental health conditions such as anxiety or depression.

A group of eight water-soluble vitamins: B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folate) and B12 (cobalamin). Many act as helpers (cofactors) for enzymes that release energy from food and make neurotransmitters.

B1: see Vitamin B1 (thiamine)

B12: see Vitamin B12

B2: see Vitamin B2 (riboflavin)

B3: see Vitamin B3 (niacin, nicotinamide)

B5: see Vitamin B5 (pantothenic acid)

B6: see Vitamin B6 (pyridoxine, P5P)

B7: see Biotin (vitamin B7)

B9: see Folate (vitamin B9)

The idea that people differ in their biochemistry, so the same cause or treatment can have different effects on different people.

The study of the chemical reactions that happen inside living things. In every cell, reactions make energy, build proteins, send signals and clear waste.

A measurable sign in the body, such as a substance in blood or urine, that may indicate a process, a condition or a response to treatment. A marker is not the same as a diagnosis.

Biotin, Vitamin B7, helps enzymes process fats, carbohydrates and protein. High-dose biotin supplements can interfere with some blood tests, so tell your doctor if you take it.

A condition with episodes of unusually elevated or irritable mood and energy (mania or hypomania) and, often, episodes of depression, which may even include catatonia.

A condition in which a person is preoccupied with perceived flaws in their appearance that others do not notice or see as minor, leading to distress or repeated behaviours.

A condition marked by intense and changeable emotions, an unstable sense of self, difficulty in relationships and impulsive behaviour. Effective psychological therapies exist.

A diagram used in high-risk areas of the engineering field, such as oil and gas, aluminium refineries and the explosives industry, that shows many possible causes narrowing to one central event, then spreading to many possible effects. BBH adapts it to show how different causes can lead to similar cell-level problems and then to a range of symptoms. The Bow Tie Model focuses on the causes and the "explosion" for prevention and restoration. Outcomes are change in function, demonstrated as symptoms.

An informal term for feeling mentally slow, forgetful or unable to concentrate. It is not a diagnosis. Many things can contribute, including poor sleep, stress, illness and medicines, so it is worth discussing with a doctor.

A term used in ICD-11 for exhaustion, mental distance from work and reduced effectiveness resulting from chronic workplace stress. It is described as an occupational phenomenon, not a medical condition.

C-PTSD: see Complex PTSD

A protein made by the liver that rises with inflammation. A raised level does not show the cause. Doctors use it alongside other information. Levels may vary with iron levels.

A blood protein that carries and stores most of the body's Copper. Copper not held by caeruloplasmin is called free copper and is very reactive. CP breaks down when it releases copper. It is measured when doctors check copper status.

A mineral which is needed for bones and teeth and for nerve, muscle and heart function. Blood calcium is tightly controlled by the body.

A compound that helps move fats into mitochondria to be used for energy. The body makes it, and it is also found in meat and dairy.

A detailed description of one person's experience, or a small group. It can raise new ideas but cannot show cause and effect. It is a quick effective way to pass on information to other medical recipients.

CAT: see Catalase (CAT)

An enzyme that enables ferritin to very quickly break hydrogen peroxide into water and oxygen. It contains iron in a haem group. Iron is the co-factor CAT needs to work. Working well, the conversion rate can be a million times per second.

CBT: see Cognitive behavioural therapy (CBT)

The basic unit of life. Your body has trillions of cells. Each takes in nutrients, makes energy and clears waste.

Cell function means a cell doing its normal jobs: making energy, repairing itself, passing signals and clearing waste. Cellular dysfunction means one or more of these jobs is not working well. Possible contributors include nutrient shortages, toxins, infection, inflammation, physical imbalances, sleep and exercise changes and oxidative damage and more.

A popular imprecise phrase suggesting that a mental health condition is caused by too much, or too little, of one brain chemical. Research does not support a single, simple chemical imbalance as the cause of most conditions. Many systems interact, including genes, stress, inflammation, nutrition and life experience.

A nutrient the body uses to make acetylcholine, a neurotransmitter involved in memory and muscle control, and to build cell membranes. It is found in eggs, meat and fish.

A trace mineral that has a role in how the body handles sugar. Evidence that chromium supplements help mood or cravings is limited.

Stress that continues over a long time. It can affect sleep, mood, immune function and many body systems.

What a condition looks like: signs are what a clinician observes or measures, and symptoms are what the person reports.

The thinking process health professionals use to move from a person's story and test results to a working explanation and a plan. It combines quick pattern recognition with slower, deliberate analysis.

Cobalamin: see Vitamin B12

A molecule in the mitochondria that helps make cell energy (ATP) and also acts as an antioxidant. The body makes it, and some statin medicines lower its levels. Evidence for supplements in mental health is limited.

A non-protein chemical compound or metallic ion required for an enzyme's role as a catalyst. Co-factors are considered helper molecules that are essential to trigger the action of an enzyme and are essential for the enzyme to be activated.

A structured talking therapy that helps people notice and change unhelpful patterns of thinking and behaving. It has a large research base across many conditions, and trauma-focused versions are used for PTSD.

When a person has more than one condition at the same time, for example mental health issues and diabetes and/or cardiac issues.

A condition described in ICD-11 that can follow prolonged or repeated trauma. As well as PTSD symptoms it includes difficulty managing emotions, a negative sense of self and difficulty in relationships.

Patterns of behaviour in children and teenagers that repeatedly break rules or the rights of others (conduct disorder), or involve ongoing angry, defiant behaviour toward authority (oppositional defiant disorder).

A mineral needed for energy production, iron handling and making neurotransmitters. Too little or too much can cause problems. Serum copper can be measured by a blood test.

A comparison of copper and zinc levels, most often measured in blood. The two minerals compete for absorption, and both are needed by CuZn-SOD. A ratio is only one measure and needs a doctor to interpret alongside other results.

CoQ10: see Coenzyme Q10 (CoQ10, ubiquinol)

A hormone made by the adrenal glands that helps the body respond to stress and follows a daily rhythm, highest in the morning. A single cortisol result needs a doctor to interpret.

Professionals who provide talking therapy. In Australia, the titles 'counsellor' and 'therapist' are not protected in the same way as 'psychologist', so it is worth checking a person's training and professional association.

Ongoing learning that registered health professionals do to maintain and improve their skills. Requirements differ by profession. CPD points are under self-learning (Australia). We currently (Oct 2026) have not applied for credit points as the course provides new material, not a revamp of previous knowledge. We continue to support original research and to make this material available to all stakeholders.

A compound that helps cells, including brain and muscle cells, store and release quick energy. The body makes it and it is found in meat and fish. Research on creatine in mental health is early.

Cu:Zn ratio: see Copper-to-zinc ratio

CuZn ratio: see Copper-to-zinc ratio

CuZn SOD: see Superoxide dismutase (SOD, CuZn-SOD, MnSOD)

An organisation endorsed by the Australian Taxation Office to receive gifts that donors can claim as a tax deduction. Bio Balance Health's donations of $2 or more are tax deductible. We aim to use profits to secure further research to support the original research we have been supporting for over 20 years.

A mental health condition in which a person has low mood or loses interest or pleasure in most things, together with changes such as sleep, appetite, energy and concentration, for at least two weeks and enough to affect daily life.

The identification of a mental health condition by a registered health professional, using history, examination (and sometimes tests), and criteria based on symptom clusters such as the DSM-5-TR or ICD-11.

The point at which the chance of a condition is high enough that testing or treatment is worth it. Below it, a professional may watch and wait. Above it, they test or act.

In Australia, vitamins and minerals sold as supplements are regulated by the TGA as complementary medicines. These are called nutraceuticals. Products on the register carry an AUST L or AUST R number. A supplement can still interact with prescribed medicines. Patients must tell all their practitioners what nutraceuticals they are taking.

Dietitians have university training in nutrition and dietetics, and an Accredited Practising Dietitian (APD) is credentialed through Dietitians Australia. The title 'nutritionist' is not protected in Australia.

The process of listing and weighing the possible different diseases which have similar symptoms, including physical ones such as thyroid problems or low iron, before proceeding to further examination and exploration before settling on a most probable diagnosis.

Feeling disconnected from yourself, your surroundings, your memories or your identity. It can be a short-lived response to stress or part of a dissociative disorder.

A neurotransmitter involved in movement, motivation, reward and attention.

The Diagnostic and Statistical Manual of Mental Disorders, published by the American Psychiatric Association. It lists diagnostic criteria for mental health conditions based on symptoms.

Serious conditions involving disturbed eating behaviours and distressing thoughts about food, weight and body image. They affect physical and mental health and need specialist support from a registered health professional. Management requires collaboration between all care networks.

Minerals that carry an electric charge in body fluids and help nerves, muscles and the heart work. Blood electrolytes are checked routinely, and abnormal results always need a doctor's review.

The movement of electrons from one molecule to another. Understanding of normal and abnormal electron transfer function within cell is the biochemistry knowledge essential to restore cell health.

Difficulty managing the strength or length of emotions. It appears in many conditions, including trauma-related conditions, borderline personality disorder and ADHD, and it is not a diagnosis on its own.

A protein that speeds up a biochemical reaction in the body. Enzymes need cofactors and coenzymes to be activated. Co-enzymes are an organic molecule, lightly bound and act as carriers. Co-factors can be organic or inorganic which are tightly bound to the enzyme. They increase the rate of the enzymic reaction.

The two long-chain omega-3 fats found mainly in oily fish. DHA is a major building block of the brain. Fish oil supplements have been studied in depression, with mixed results.

Biochemical tags on or around DNA that switch genes on or off without changing the genetic code. They can be influenced by life experience.

A biochemical reaction in which free (unbound) iron, and to a lesser extent copper, reacts with superoxide anions to form hydroxyl radicals. When copper and zinc are out of balance and too low, iron can be either prooxidant or antioxidant. Which role it plays depends on copper and zinc levels in a cell. It is the main reason iron is both essential and yet potentially harmful in cells.

A protein that stores iron. A blood ferritin test is a common way for doctors to estimate the body's iron stores. Ferritin can also rise with inflammation, so results need a doctor to interpret.

Fish oil: see EPA and DHA (fish oil)

A B vitamin needed to make DNA and to support methylation. Folic acid is the form used in supplements and fortified foods.

Folic acid: see Folate (vitamin B9)

A term for approaches that look for underlying causes of illness. It is not a recognised medical specialty in Australia, and the term is used in different ways.

The main calming neurotransmitter in the brain. It reduces nerve cell activity.

A small difference in the DNA sequence between people. Most variants are harmless. Some change how an enzyme works.

A medical doctor who is usually a person's first point of contact in the health system. GPs assess mental health, order tests, prescribe medicine, make mental health treatment plans and refer to specialists.

The main exciting neurotransmitter in the brain. It increases nerve cell activity and works in balance with GABA.

An amino acid that is a fuel for gut lining cells and a building block for the neurotransmitters glutamate and GABA.

An antioxidant made inside cells that helps protect them from oxidative damage and helps clear some toxins.

Glutathione peroxidase: see Glutathione peroxidase (GPx)

A family of enzymes that use glutathione to break down hydrogen peroxide and damaged fats into water and harmless products. Many of them need the mineral selenium to work.

The simplest amino acid. It is used to build proteins and glutathione, and it acts as a calming signal in parts of the brain and spinal cord.

GP: see General practitioner (GP)

GPx: see Glutathione peroxidase (GPx)

Two-way communication between the gut and the brain through nerves, hormones and the immune system. Gut bacteria influence it. Research on mental health is active and still early.

H2O2: see Hydrogen peroxide (H2O2)

The process that breaks down the iron-containing part of red blood cells. Its by-products include bilirubin and urobilinogen.

Metals such as lead and mercury can be harmful to the nervous system at high levels. Poisoning is diagnosed by a doctor using specific tests. General 'detox' claims are not supported by good evidence.

A molecule involved in immune responses, digestion and brain signalling. Whole blood histamine can be measured. 'Histadelia' and 'histapenia' are older labels that are not part of mainstream diagnosis.

An amino acid in the blood that is processed using folate, B12 and B6. High levels are linked to heart disease and have been studied in mental health.

The system linking the brain (hypothalamus and pituitary) with the adrenal glands to manage stress. Cortisol is its main hormone. 'Adrenal fatigue' is not a recognised medical diagnosis.

A reactive oxygen species from the conversion of superoxide anion by the enzyme Copper.Zinc:SOD.

The most reactive of the reactive oxygen species. It damages fats, proteins and DNA almost wherever it forms, and the body has no enzyme that removes it, so cells rely on preventing its formation, for example by keeping iron and copper tightly bound and zinc levels adequate.

A state of being constantly alert and scanning for danger, often with a strong startle response and trouble relaxing or sleeping. It is common after trauma.

The World Health Organization's International Classification of Diseases, 11th revision. It is used worldwide to classify health conditions, including mental disorders.

The body's response to injury, infection or irritation. Short-term inflammation protects. Long-term, low-level inflammation is linked to many conditions, and researchers are studying links with depression and other mental health conditions.

A person's formal signed agreement to a test or treatment after being told the benefits, risks and alternatives.

A sugar-like molecule the body makes and gets from food. It takes part in cell signalling. Some small studies have looked at inositol in mental health conditions, and the evidence is limited.

Ongoing difficulty falling asleep, staying asleep or waking too early, at least three nights a week for three months or more, with effects on daytime functioning.

Unwanted thoughts, images or memories that come into the mind without being invited. After trauma they can feel like reliving the event (a flashback). Unwanted thoughts are also common in obsessive-compulsive disorder.

A trace mineral the thyroid gland needs to make thyroid hormones. In Australia, most bread is made with iodised salt, and pregnant and breastfeeding women are advised to speak to their doctor about iodine.

A mineral needed to carry oxygen in the blood and for many enzymes, including those that make dopamine and serotonin. Both too little and too much iron can cause problems, so iron should only be taken after a doctor has checked blood tests.

A set of blood tests that show how much iron the body has and can use, including ferritin. Iron is needed to carry oxygen and to make neurotransmitters.

A name used for a pyrrole-related substance measured in urine. See Pyrroles.

A way to rank how reliable a type of study is. From weaker to stronger: expert opinion, case report, observational study, open-label or pilot study, randomised controlled trial, systematic review.

Lithium is found in small amounts in soil and drinking water. At prescription doses it is a medicine used mainly for bipolar disorder, and it needs regular blood tests and medical supervision. Never start or stop lithium without your doctor.

Blood tests that show how well the liver is working. They are important for safe use of many medicines and supplements.

A mineral needed for hundreds of enzymes and for nerve and muscle function.

A trace mineral needed for some antioxidant and bone-forming enzymes. Too much can affect the nervous system, which is rare and usually linked to occupational or environmental exposure.

A planned review by a doctor or pharmacist to check that each medicine is still needed, safe and working. Reducing or stopping a medicine should only happen with medical supervision, because stopping suddenly can cause withdrawal effects or a return of symptoms. The word Medicine applies to drugs which are regulated to only be prescribed by medical doctors. Vitamins and minerals are nutraceuticals. The recommended daily dose is a guide to allowable maximum intake.

A hormone the brain releases in the evening to trigger sleep. In Australia most melatonin products need a prescription. There are natural products which assist with melatonin action. Adequate magnesium also assists.

Mental health care plan: see Mental health treatment plan

A registered nurse with specialist training in mental health care. Some are credentialed to provide care under certain Medicare programs.

A plan a GP prepares with a person after a mental health assessment. In Australia it can allow Medicare rebates for a set number of sessions with eligible mental health professionals. Rules change, so check Services Australia or ask your GP.

A basic biochemical process in which a small molecular group (a methyl group) is added to a molecule. It helps control genes and helps make neurotransmitters. It depends on nutrients such as folate, B12 and B6.

The active form of folate that the body uses in methylation. It is sold as a supplement and as a prescription product in some countries. Whether it works better than ordinary folic acid for mental health is still being studied.

MHTP: see Mental health treatment plan

The community of bacteria and other microbes that live in your body, mostly in the gut.

A vitamin or mineral the body needs in small amounts. Examples are zinc, copper, iron, folate and vitamin B6.

Structures inside cells that make most of the cell's energy, in the form of ATP. They are also a main source of reactive oxygen species. Essential for life.

An enzyme, and the gene that makes it, involved in processing folate. Common gene variants change how well the enzyme works.

Care in which several health professionals, such as a GP, psychologist, psychiatrist and pharmacist, work together with the person. Good communication between them helps avoid gaps and drug interactions.

A form of the amino acid cysteine. The body uses cysteine to make glutathione, a major antioxidant. In hospitals NAC is also a medicine for paracetamol overdose. Research on NAC in mental health conditions is early and mixed.

NAC: see N-acetylcysteine (NAC)

A form of complementary health care that uses herbs, nutrition and lifestyle advice. Naturopathy is not a nationally registered profession in Australia, so training and standards vary between practitioners.

A messenger molecule that carries signals between nerve cells. Examples are serotonin, dopamine, GABA, glutamate and noradrenaline.

Niacin: see Vitamin B3 (niacin, nicotinamide)

A term for a food-derived product, such as a vitamin or mineral, used for a health purpose. Supplements are regulated therapeutic goods in Australia and should be used on advice from a registered health professional.

The study of how nutrients and genes affect each other. It is an active research area with limited clinical use so far.

A study in which researchers watch what happens in groups of people without changing anything. It can show links, but not cause.

A condition with obsessions, which are unwanted, repeated thoughts, images or urges, and compulsions, which are repeated behaviours or mental acts a person feels driven to do to reduce distress.

Fats found in oily fish and some plants, needed for cell membranes and brain function. Some trials have studied them in depression, with mixed results.

A network of reactions that moves single carbon units around the cell. It supports methylation and the making of DNA building blocks. BBH offers a lecture on this topic available through our website.

A trial in which everyone, participants and researchers, knows what treatment is being given. It is useful for early findings, but results can be affected by expectation, so it cannot show cause and effect.

An approach that proposes treating mental conditions with optimal amounts of nutrients. It is contested, and evidence for it is mixed or limited.

Overthinking: see Rumination (including trauma rumination)

A state in which cells face more reactive oxygen species than their defences can handle. It is linked to ageing and many illnesses.

P5P: see Vitamin B6 (pyridoxine, P5P)

A panic attack is a sudden surge of intense fear with physical symptoms such as racing heart, sweating or breathlessness. Panic disorder involves repeated unexpected attacks and ongoing worry about having more.

Pantothenic acid: see Vitamin B5 (pantothenic acid)

How a disease develops, from the first trigger to the signs and symptoms, including what happens in cells, tissues and organs along the way.

The branch of medicine that studies disease by testing samples such as blood, urine or tissue. Pathology results are interpreted by a doctor alongside symptoms and history.

Checking of research by independent experts before it is published in a journal.

A long-lasting form of low mood, present on most days for at least two years in adults, usually with other symptoms such as low energy, poor sleep or appetite change.

Long-standing patterns of thinking, feeling and behaving that differ markedly from what is expected, cause distress or difficulty, and are present across many situations.

A registered health professional who supplies medicines and can advise on how medicines and supplements interact. A pharmacist can often spot interactions between supplements and prescribed medicines.

An intense, lasting fear of a particular object or situation, such as heights or animals, out of proportion to the real danger.

A small early study done to test whether a bigger study is worthwhile. It cannot show that a treatment works.

An inactive treatment given in a trial. The placebo effect is the improvement some people feel because they expect to improve.

A condition that can follow exposure to a traumatic event, with intrusive memories, avoidance, negative changes in mood and thinking, and feeling constantly on guard, lasting more than a month.

Depression that begins during pregnancy or after the birth of a baby. It is common and treatable, and help is available.

Potassium: see Electrolytes (sodium, potassium, chloride)

A thinking error in which a professional settles on one explanation too early and stops considering others.

A condition in which marked mood symptoms, such as irritability, low mood or anxiety, occur in the week before a period and ease soon after it starts.

Live micro-organisms, such as certain bacteria, that may have health effects when taken in enough amounts. Research on probiotics for mental health is early.

Intense longing for, or preoccupation with, someone who has died, lasting much longer than expected for a person's culture and causing major distress or difficulty functioning. Grief itself is natural and is not an illness.

A medical doctor who has completed specialist training in psychiatry. In Australia, a person usually needs a referral from a GP to see one. Psychiatrists can diagnose, prescribe medicine and provide therapy.

The medical specialty that diagnoses, treats and prevents mental illness. Psychiatrists are medical doctors who can prescribe medicine and also use psychological treatments. Diagnoses in psychiatry are usually made from symptoms, using manuals such as the DSM-5-TR and ICD-11.

A health professional trained in how people think, feel and behave who provides assessment and talking therapies. Psychologists are registered with AHPRA. They do not prescribe medicine. Clinical psychologists have extra postgraduate training and endorsement.

An experience in which a person loses some contact with shared reality, for example hearing or seeing things others do not, or holding fixed beliefs that others do not share. It is a symptom, not a diagnosis by itself, and can have many causes.

Treatment that uses structured conversations and skills practice, rather than medicine, to help with mental health conditions. There are many types, including cognitive behavioural therapy.

Prescribed medicines that act on the brain and are used in mental health conditions, including antidepressants, antipsychotics, mood stabilisers and anti-anxiety medicines. Do not stop or change them without consulting the prescriber.

PTSD: see Post-traumatic stress disorder (PTSD)

Pyridoxine: see Vitamin B6 (pyridoxine, P5P)

A name used by some for a pattern of high urinary pyrroles. BBH uses the term 'high urinary pyrroles' as research has shown it is NOT a distinct condition, diagnosis or inherited trait.

Small molecules that form when the body breaks down certain substances, including parts of old blood cells. Some researchers think higher amounts in urine may be a potential biomarker of oxidative stress. BBH calls this 'high urinary pyrroles'.

A study in which people are randomly placed into groups, for example one receiving a treatment and one receiving a placebo, then compared. It is one of the best ways to test whether something works.

Highly reactive molecules containing oxygen that cells make as a by-product of normal biochemistry. In small amounts they act as signals. In excess they can damage cells.

The amount of a nutrient that meets the needs of nearly all healthy people. In Australia these are set in the Nutrient Reference Values by the NHMRC.

A pair of linked biochemical processes in which one molecule loses electrons (oxidation) and another gains them (reduction). Redox balance describes how well the cell manages these processes.

The range of results seen in most healthy people. A result outside the range is not always a problem, and a result within it is not always optimal for an individual. Often reference ranges are obtained from a mean of tests of unwell people, not a mean of a healthy population.

A letter or request from one health professional, usually a GP, asking another professional to see a person. Many specialist services and Medicare rebates need one from a GP.

Riboflavin: see Vitamin B2 (riboflavin)

Repeatedly going over the same thoughts, usually about distress, its causes or its meaning, without moving toward a solution. It is common in depression, anxiety and after trauma, where it often centres on why something happened.

SAM-e: see SAMe (S-adenosylmethionine)

A molecule the body makes that passes methyl groups to other molecules in methylation. SAMe supplements can interact with antidepressants, so speak to your doctor before using them.

A condition that combines symptoms of schizophrenia, such as hallucinations or delusions, with a major mood episode of depression or mania.

A serious condition that affects thinking, perception, emotion and behaviour. It may include hallucinations, delusions and disorganised thinking.

Depression that follows a seasonal pattern, most often starting in autumn or winter and easing in spring.

A trace mineral needed for antioxidant enzymes and for thyroid hormone activity. Too much selenium is toxic, so supplements should be taken only on professional advice.

A neurotransmitter involved in mood, sleep and digestion. Most of the body's serotonin is made in the gut.

A way of working in which the health professional and the person look at the options together, and the person's values and goals help decide the plan.

Ordering many tests in all directions without a clear reason for each. It can be costly and can produce misleading results.

SOAP: see SOAP notes (SOAP process)

A common way for health professionals to record a consultation, in four parts: Subjective (what the person tells you), Objective (what is observed or measured, such as examination findings and test results), Assessment (the professional's interpretation or working diagnosis) and Plan (next steps, such as tests, treatment and follow-up).

Strong fear or anxiety about social situations where a person might be judged, which leads to avoiding them or enduring them with great distress.

SOD: see Superoxide dismutase (SOD, CuZn-SOD, MnSOD)

Sodium: see Electrolytes (sodium, potassium, chloride)

SSRI: see Psychotropic medicines (antidepressants and others)

A pattern of using alcohol or other drugs that continues despite harm, with symptoms such as cravings, loss of control, tolerance or withdrawal. Help is available from registered health professionals.

A reactive oxygen species made when a stray electron reaches an oxygen molecule. It is produced constantly as a by-product of energy production in the mitochondria. The enzyme superoxide dismutase (SOD), with its cofactors copper and zinc, converts it to hydrogen peroxide and water.

Superoxide dismutase: see Superoxide dismutase (SOD, CuZn-SOD, MnSOD)

A family of enzymes that are the cell's first step in managing superoxide anion. They convert superoxide anion to hydrogen peroxide and oxygen. Copper-zinc SOD (CuZn-SOD, also called SOD1) works mainly in the cell fluid and needs both copper and zinc. Copper as the co-factor is free copper. Manganese SOD (MnSOD, SOD2) works inside mitochondria.

Something a person feels or experiences, such as low mood or tiredness. Symptoms are something that a patient reports. Patients can forget some symptoms or incorrectly report other symptoms. A sign is something an observer or test can detect.

A careful, structured summary of all the good studies on a question. A meta-analysis combines their results statistically.

A way of working through the objective part of a consultation in three steps: Testing (measure what can be measured), Assessment (interpret the results with the person's story) and Plan (agree the next steps, including follow-up measures).

An amino-acid-like compound found in meat, fish and the brain. It has roles in nerve function and cell protection.

Australia's regulator of medicines, supplements and medical devices. It sets rules for advertising therapeutic goods.

Thiamine: see Vitamin B1 (thiamine)

Blood tests, including TSH, that show whether the thyroid gland is making the right amount of hormone. Thyroid problems can cause symptoms that look like depression or anxiety.

The lasting emotional, mental and physical effects of an event or series of events overwhelmed a person's ability to cope. Many people have a distressing experience, and only some go on to develop a condition such as PTSD.

Trauma rumination: see Rumination (including trauma rumination)

Depression that has not improved after adequate trials of at least two different antidepressants. Options exist, so a person should talk to their doctor.

BBH's Protocol uses Tri-alloy as the name for three minerals that work together in lipid heavy neurological cells. The mechanism to maintain homeostasis which allows the mitochondria to function to their best relies on the Tri-alloy minerals, free copper, zinc and ferritin as cofactors for the cell's defence enzymes: SOD and CAT, and selenium for GPx. BBH teaches the balance of these minerals matters as much as how much of each is present.

An essential amino acid from protein-rich food. The body uses it to make serotonin and melatonin. Tryptophan supplements can interact with antidepressants, so check with your doctor or pharmacist.

An amino acid the body uses to make dopamine, noradrenaline, adrenaline and thyroid hormones.

The highest daily intake of a nutrient that is unlikely to cause harm in most people. Going above it for long periods can be harmful. Vitamin B6 and some minerals have limits well below the doses sold in some supplements.

A normal by-product of gut bacteria breaking down bilirubin from old blood cells. Some urine tests report it together with pyrroles. Separating the two matters for interpreting a result.

A fat-soluble vitamin needed for vision, immunity and cell growth. Too much preformed vitamin A (retinol) can be harmful, especially in pregnancy, so supplements should only be used on professional advice.

A vitamin the body needs to turn carbohydrate into energy and to keep nerves working. Severe deficiency, seen most often with heavy alcohol use or poor nutrition, can seriously affect the brain and needs urgent medical care.

A vitamin needed for nerves, red blood cells and methylation. Low B12 can cause tiredness and nerve and mood symptoms.

A vitamin used in energy production and in recycling folate. It is found in milk, eggs, meat and green vegetables.

A vitamin the body uses to make NAD, a molecule central to energy production. High doses of some forms can cause skin flushing and liver problems, so high-dose niacin should only be taken under medical supervision.

A vitamin needed to make coenzyme A, which the body uses in energy production and to make some hormones and neurotransmitters. It is found in many foods.

A vitamin needed for many enzymes, including those that make serotonin and neurotransmitters. Taking too much B6 over time can damage nerves. B6 is often added into processed foods and supplements.

A vitamin that works as an antioxidant and is needed to make collagen and some neurotransmitters, including noradrenaline. Humans cannot make it, so it must come from food, such as citrus fruit, capsicum and kiwifruit.

A vitamin and hormone needed for bones and the immune system, made in the skin with sunlight. Studies of vitamin D and mood have given mixed results.

A fat-soluble vitamin that works as an antioxidant in cell membranes. It is found in nuts, seeds and plant oils.

A mineral needed by hundreds of enzymes. Plasma zinc can be measured by a blood test. Interpreting results needs a doctor.

A compound the body makes from tryptophan on the way to serotonin. Taking 5-HTP together with antidepressants or other serotonin-raising medicines can cause a dangerous reaction called serotonin syndrome, so speak to your doctor first.

5HTP: see 5-HTP (5-hydroxytryptophan)