Neuroimmunology Flashcards
Immunopsychiatry / Neuroimmunology
Study of the connection between the brain and the immune system
Basic Premise of the Immunopsychiatry Lecture
Autoimmune response to infection is associated with a transdiagnostic biological vulnerability to psychiatric disorders
Evidence for Immunopsychiatry link
i) Infection,
ii) autoimmune disorders and
iii) elevated markers of inflammation
are all risk factors for later psychiatric disorders
And other way round: stress disorder -> increased risk of autoimmune disease
What kinds of psychiatric disorders are implicated in neuroimmunology?
Mood disorders, stress disorders, Schizophrenia, and more
Thought to induce ‘transdiagnostic vulnerability’, rather than any specific disorder
Increased risk of Schizophrenia following hospitalisation with infection?
50% higher
Even more if the infection was bacterial
Autoimmune diseases
Over 100 of them
In brain, blood, nerves, muscles, bones, lungs, skin etc.
True or False: the link between psychosis and immunology has only recently been noticed
False
Long history in medicine going back over 100 years
Evidence for Plausible Causal Link (infection -> psychiatric disorders)
Immunological inflammation induces fatigue, withdrawal, depression-like symptoms etc. Potentially evolutionary advantageous behaviour induced by immune system
Increased biomarkers of inflammation in the blood and CSF found for many psychiatric disorders. Specifically increased levels of cytokines found in patients with SCZ and especially MDD
Cytokines given as a cancer treatment; been found to increase depression in these patients
Animal models: administration of immune stimuli and cytokines induces depression-like symptoms in mice. Similar results with SCZ
Causation Problem
Chickens, eggs, yada yada: causation is not clear, probably bidirectional
Immune response could be defending against an oncoming disorder: maybe we only see the people who have an unsuccessful response
Two types of immunity
Innate immunity: rapid response to infection
T cells and many more
Adaptive immunity: slow response to infection
T cells, B cells, antibodies
NMDA receptor (NDMAR)
[Expect a question on this!]
Glutamate system
‘Coincidence detector’ crucial for learning and memory
NDMAR antibodies (especially in CA1 area in hippocampus) can cause reduced NMDAR density
Anti-NMDA receptor encephalitis
[Expect a question on this!]
Classic neuropsychiatric syndrome: brain inflammation caused by antibodies
Killed cuddly Berlin boi, Knut
80% female, mean onset 21 years
Typical progression: viral infection -> psychiatric symptoms (esp. psychosis) -> coma -> long-term deficits
Neuroimmunological effects of anti-NMDA receptor encephalitis
Possible link between a (‘paraneoplastic’) subtype of the condition and developing various psychiatric symptoms
Clinical Relevance of it all
Diagnosis?
Using immunological biomarkers? Maybe, but it’s difficult. Likely that by the time you find out that inflammation caused SCZ, it happened 15 years ago so info is not that helpful
Therapy?
Some evidence that some anti-inflammatory treatments (including cytokine inhibitors) could be effective for SCZ or especially MDD.
Might find ‘inflammatory subtypes’ for whom this kind of treatment works.