pathophysiology

Parkinson’s Disease

• Loss of dopaminergic neurons in the substantia nigra of the basal ganglia which produces dopamine (DA)

• Resulting in deficiency of DA which is the main cause of the symptoms & progression of Parkinson's D

Epilepsy

• Neuronal depolarization (“firing”) depends on membrane potential.
• There is excessive release of excitatory neurotransmitters (e.g. acetylcholine, histamine, cytokines, etc) and insufficient release of inhibitory neurotransmitters (e.g. GABA, dopamine)
• This imbalance of excitatory and inhibitory receptor / ion channel function favours depolarization.
• A seizure occurs when there is excessive synchronous depolarization, usually starting from defined regions (“foci”) and spreading to other regions.

Migraine

• Activation of trigeminal sensory nerves triggers the release of vasoactive neuropeptides from perivascular axons.

• Vasodilation of dural blood vessels may occur with extravasation of dural plasma resulting in inflammation.

• Specific populations of vascular and neuronal serotonin (5-HT) receptor subtypes may be involved

Major Depressive Disorder (MDD)

Based on the monoamine deficiency
theory where low levels of
monoamines neurotransmitters
like serotonin, norepinephrine and
dopamine at the synaptic cleft cause depression.

Anxiety

• Associated with chronic norepinephrine stimulation at the cortico-striatal-thalamic-cortical (CSTC) loop and the reduced serotonin inhibitory actions at the amygdala
• Leading to a state of hyperarousal and giving rise to the symptoms of stress and anxiety
• Other inhibitory neurotransmitters like gamma-aminobutyric acid (GABA) are involved.

Major Depressive Disorder (MDD)

Based on the monoamine deficiency

theory where low levels of

monoamines neurotransmitters

like serotonin, norepinephrine and

dopamine at the synaptic cleft cause depression.

Generalized Anxiety Disorder (GAD)

• Associated with chronic norepinephrine stimulation at the cortico-striatal-thalamic-cortical (CSTC) loop and the reduced serotonin inhibitory actions at the amygdala

• Leading to a state of hyperarousal and giving rise to the symptoms of stress and anxiety

• Other inhibitory neurotransmitters like gamma-aminobutyric acid (GABA) are involved.