Health psychology and behavioural medicine Vorlesung 13

Explain the role of the stomach in feeling nervous

- Approx 40,000 bacteria species in human gut --> friendly, good for us

- Exact composition depends on genetics, age, nutrition, physical activity, environmental factors, stress, infections, diseases, and use of antibiotics

- Newborn microbiome dependent on maternal microbiome and diet - gut microbiome regulates immune system & inflammatory response to infection

- When nervous, the ANS produces corticotrophin releasing factor - this impairs normal gut function --> we experience stomach problems

- why does that happen? --> adaptive --> fight or flight --> you want your muscles to function as good as they can --> no digestion

Explain the microbiota-gut-brain axis

1. Overview of the Diagram

- This image visually represents the bidirectional (two-way) communication between:

- Microbiome (the community of microorganisms in the gut)

- Gut (especially the intestines)

- Brain

- The central box lists the key biological pathways that allow this communication to occur.

2. The Brain-Gut-Microbiota Axis Explained

- Microbiome

Illustrated on the left with diverse microbes like bacteria and viruses.

These microbes influence and are influenced by the gut and brain.

- Gut

Shown on the right as the intestines.

It hosts the microbiome and has a dense network of nerves, immune cells, and hormone-producing cells.

- Brain

At the top, representing the central nervous system.

Receives and sends signals to the gut and microbiota.

3. Key Pathways (middle box in the diagram)

These are the main routes through which the microbiota-gut-brain interaction happens:

Pathway Description

Immune system Gut microbes regulate immune responses; inflammation can affect brain health.

Vagus nerve system A major nerve that directly connects the gut to the brain. Acts like a "highway" for signals.

Neuroendocrine system Hormones (like cortisol, serotonin) mediate stress and emotion; influenced by gut activity.

Circulatory system Microbial metabolites (e.g., SCFAs, tryptophan) enter blood and affect brain function.

💡 Enteric nervous system Known as the "second brain" in the gut; works semi-independently to control digestion and send signals to the brain.

4. Arrows Show Two-Way Communication

Green arrows (from brain to gut and microbiome): The brain influences gut function through stress, emotion, and hormones.

Blue arrows (from gut/microbiome to brain): The gut and microbiota send feedback to the brain that can affect mood, behavior, and cognition.

Where are gut microbiota involved?

in the functioning of the HPA (German: HHN) - axis

what is the HPA axis?

Components of the HPA Axis:

1. Hypothalamus: Releases CRH (corticotropin-releasing hormone) in response to stress.

2. Pituitary Gland: Responds to CRH by releasing ACTH (adrenocorticotropic hormone) into the bloodstream.

3. Adrenal Glands: Stimulated by ACTH to release cortisol, the primary stress hormone.

Function:

• When a person experiences a stressful event, the hypothalamus activates the HPA axis.

• This leads to increased cortisol levels, which help the body respond by:

  • Increasing glucose availability for energy

  • Suppressing non-essential functions (e.g., immune response, digestion)

  • Modulating mood and arousal

What may cause abnormal stress reactivity?

A dysregulated microbiome --> conversely, excess stress can negatively affect the gut

What co-occurs frequently with psychiatric disorders (IBS and anxiety/depression)?

Gastrointestinal conditions suspected to involve alterations in the gut microbiota

What ahppens during phases of stress or anxiety?

stomach muscles convulse and stomach acid is released, potentially altering the microbiome balance

Explain the disease Model IBS (Reizdarmsyndrom) --> wie viele haben es, was ist es, wodurch wird es charakterisiert?

- Irritable Bowel Syndrome (IBS) affects 5-10% of global population. It is characterised by ongoing abdominal pain, bloating and bowel problems

- 25 - 30% of individuals with IBS suffer from anxiety symptoms and/or depressive symptoms

- The relationship appears to be bidirectional - those who start out with mental health symptoms are more likely to develop IBS than the general population, and vice versa.

Wo kann man IBS zuordnen? Erläutere weshalb

zu den Low threshold syndromes --> bidirectional --> when one is there, the other is also more bad

--> Certain disorders (fibromyalgia, migraine, chest pain following myocardial infarction) (have no identifiable markers--> hier schon) , yet cause patients intense pain.

- These disorders may:

• Involve a heightened sensitisation of the autonomic nervous system

• Occur in individuals with a genetic predisposition, but be triggered by major life stressors

• Become chronic due to an ongoing interrelation of painful symptoms and heightened sensitivity

- (These disorders have no clear biological cause or effect, yet produce real physical sensation --> hier schon). However, symptoms CANNOT be fully attributed to poor management of emotional state

Define mental disorder (APA)

... any condition characterized by cognitive (thinking) and emotional (feeling) disturbances, abnormal behaviors, impaired functioning, or any combination of these. Such disorders cannot be accounted for solely by environmental circumstances and may involve physiological, genetic, chemical, social, and other factors.

--> looking at the way people act, think and feel --> as soon as this is abnormal and we can't explain this by an environmental factor or other fundamental reason --> field of mental disorder (wide area to cover --> von Depression bis ADHS...)

Define the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) --> DSM V

▪ Categorises and classifies signs and symptoms of mental disorders

▪ «Statistical» approach to grouping symptoms

▪ Aims to ground defintions of mental disorders on empirical evidence

▪ Used most frequently in the USA, important influence on English-language literature ▪ Focus on quantiative symptom checklist

Define the International Classification of Disease (11th ed.) --> ICD 11

▪ Tool for recording & coding health information and mortality causes

▪ 85,000 codes including disease types, symptoms, physical abnormalities...

▪ Alternative to DSM 5, widely used in Europe and other countries

▪ Focus on qualitative description of disorders

To what refers comorbidity?

______ refers to the presence of one or more secondary diagnoses present at the same time as the main diagnosis in a patient

By what are mental disorders frequently accompanies? What rates are reported?

Mental disorders are frequently accompanies by mental comorbid disorders. Rates of 50-80% are commonly reported

What will poor functioning in one mental domain freqently impact?

mood, social functioning, etc.

What is often appealing to individuals struggling with mental symptoms?

Self-medication

Erläutere the comorbid mental and physical illness

- The presence of a mental illness together with a physical illness increases the risk of poor outcomes for the physical illness

- The risk of mortality, higher medical costs, more frequent treatment and inability to fully resume work and social functions is increased

- Mental and physical comorbidity is complex due to the bi-directional relationships of mental and physical symptoms

- Mental disorders may also go undiagnosed as they are "masked" by physical symptoms

- Comorbid psychiatric disorders lead to poorer outcomes than the disorder alone, or the disease alone

With what do anxiety disorders have high rates of comorbidity?

with physical disorders

→ Particularly prevalent in people with IBS (25%) and asthma (25%)

What does "anxiety disorder" all include?

generalised anxiety disorder, PTSD, and panic disorder

What is challenging idetifying in clinical populations?

Identifying anxiety in clinical populations is challenging, and the evidence for psychiatric interventions is still sparse

What are behavioural pathways for mental/physical comorbidity?

- Behavioural factors continue to acount for much of the comorbid occurrence on physical and mental disease

- Suffering from a mental disorder is associated with smoking, alcohol and drug use, and lower physical activity.

- Medications may also contribute to fatigue and weight gain, leading to cardiometabolic disease

Name the pathways of the disease model addictive disorders

- Pathway 1: Using substance leads to direct physical harms (e.g. overdose, smoking causing COPD)

- Pathway 2: Using substance leads to negative health behaviour which causes physical disorder (e.g. alcohol dependence leads to frequent smoking)

- Pathway 3: Another risk factor independently impacts both substance use and other physical disorders (e.g. low socioeconomic status leads to higer risk of substance use and Type II diabetes)