Major Aetiological Theories Linked to Pharmacology Flashcards
What does the dopamine pathway suggest?
Abnormal dopamine activity in the brain plays a central role in the pathophysiology of schizophrenia
List the different dopaminergic pathways?
- Mesolimbic pathway
- Mesocortical pathway
- Nigrostriatal pathway
- Tuberoinfundibular pathway
How is the mesolimbic pathway associated with schizophrenia?
This pathway is associated with positive symptoms of schizophrenia (↑ dopamine activity):
1. Originates in the ventral tegmental area (VTA)
2. Projects to the limbic system (e.g., nucleus accumbens, amygdala, hippocampus)
How is the mesocortical pathway associated with schizophrenia?
This pathway is associated with negative and cognitive symptoms (↓ dopamine activity):
1. Originates in the ventral tegmental area (VTA)
2. Projects to the prefrontal cortex
How is the nigrostriatal pathway associated with schizophrenia?
Not directly involved in the symptoms of schizophrenia but:
1. D2 blockade here (e.g. from antipsychotics) causes extrapyramidal side effects (EPSEs) like acute dystonia, akathisia, parkinsonism, tardive dyskinesia.
2. Originates in the substantia nigra
3. Projects to the striatum (caudate + putamen)
How is the tuberoinfundibular associated with schizophrenia
Not directly involved in the symptoms of schizophrenia but:
1. Dopamine inhibits prolactin
2. D2 blockade here (e.g. from antipsychotics) causes hyperprolactinaemia (e.g., galactorrhoea, amenorrhoea, sexual dysfunction)
3. Originates in the hypothalamus
4. Projects to the pituiatry gland
What does the biogenic amine hypothesis suggest?
Suggests that depression is caused by a deficiency in certain neurotransmitters (biogenic amines) in the brain, particularly:
1. Serotonin (5-HT)
2. Noradrenaline (NA) (also called norepinephrine)
3. Dopamine (DA) (in some models)
What does the cholinergic hypothesis suggest?
This hypothesis proposes that cognitive decline in Alzheimer’s disease (AD) is primarily due to a deficit in acetylcholine (ACh), a neurotransmitter essential for memory and learning.
What does the cholinergic–adrenergic balance hypothesis suggest?
This hypothesis suggests that mood disorders, particularly depression and mania, may result from an imbalance between cholinergic and adrenergic (noradrenergic) activity in the brain.
What does the glutamatergic pathway suggest?
This hypothesis proposes that schizophrenia is partly due to glutamate dysfunction, specifically hypoactivity of NMDA (N-methyl-D-aspartate) receptors, a subtype of glutamate receptor
What is the amyloid cascade hypothesis?
This is the leading hypothesis explaining the pathogenesis of Alzheimer’s disease, proposing that:
The accumulation of beta-amyloid (Aβ) peptides, especially Aβ42, in the brain is the primary trigger for a cascade of pathological events leading to neurodegeneration and dementia.
