Session 2 - Neuro-biology of Depression Flashcards
How do you work out DALYs? (Burden of disease)
DALY = YLL + YLD Disability Adjusted Life Years = Years of Life Lost + Years Lived with Disability (Burden = mortality + disability)
Describe simply Bi-polar disorder:
Bi-polar disorder means that the patient will experience both manic (high) and depressive (low) mood states as a cycle.
How big of a global burden of disease will Depression have in 2020?
By 2020, depression will be the 2nd most global burden of disease
What is the largest costing factor of mood disorders? Is it direct or indirect?
Indirect - loss of employment
What does DALY stand for? And what does this mean?
Disability Adjusted Life Years
DALY = one lost year of a healthy life
Here is a diagram of the lobes of the brain. Can you give an overview of the functions of the following:
Frontal: executive descision making and movement (e.g. Playing football)
Temporal: emotion and primary auditory (listening) cortex
Parietal: sensation
Occipital: visual
The diagram shows specific regions of the brain.
Can you identify the region that is not lablled?
And what is this areas function?
Broca’s area (in left hemisphere)
Oringates speech
In the following diagram, the Parietal lobe is labelled. In what specific area is ‘understanding of language’ is its function?
Wernicke’s area
(found in the Parietal lobe)
Describe the frontal lobes functions:
Primary motor cortex
Supplementary Motor cortex
Executive functions
Broca’s area (orginates speech)
Affect on behaviour in conjuction with the temporal lobe
Describe the Parietal lobe functions:
Sensory cortex
Wernicke’s area (understanding of language)
Orientation
Recognition
Construction
Describe the roles of the Temporal Lobe:
Why is this lobe important in understanding mood disorders generally?
Primary auditory cortex
Music recognition
Memory
Emotion
Behaviour
Because both emotion and behaviour are affected here
What is the role Occipital lobe?
Primary and secondary visual cortex
How can we find out which areas of the brain are involved in mood disorders?
Brain operations, imaging (MRI, fMRI, SPECT, PET), rabies virus affecting limbic cortex, animal testing, lesions to certain areas (amygdala) lead to a loss of spontaneous aggression
What tests can be done to assess mood depression in mice and rats?
Look at appetite, weight gain, forced swimming test, and tail suspension tests.
The following picture is of the limbic system:
Please note the key structures: Anterior nucleus of Thalamus, Hypothalamaus, Amygdala, Hippocampus, Mammillary bodies, Cingulate gyrus, Dentate gyrus, septum, olfactory bundle,
What are the 3 main functions of the limbic system?
Emotion, Motivation and Memory (EMM)
The Amygdala is part of the limbic system (which controls emotion, motivation and memory).
What is the function of the Amygdala?
Critical for conditioning and emotional processing.
Input from a range of sensory areas
Connected to areas that control autonomic function: motor action, neuroendocrine responses
What imaging techniques can be used to look at how mood disorders can affect the brain?
MRI/CT (Magnetic resonance imaging)
fMRI (functional)
SPECT (Single-photon emission computed tomography)
PET (positron emission tomography)
An MRI scan can be used to look at the brain in someone who is depressed. Typically, white matter changes are related to depression.
How is a patients response to treatment affected with white matter changes already?
There is a poor response.
What is the role of the Hippocampus ?
What happens to the size/volume of the hippocampus in a depressed state?
The hippocampus has a major role in memory functions.
In depression, the hippocampal volume was consistently and significantly reduced in patients with depression.
This reduction is significantly correlated with the duration of the illness
Functional imaging looks at the activitiy of certain regions of the brain. Examples incluude fMRI, PET and SPECT (not MRI).
Explain how fMRI works?
fMRI focuses on blood flow.
Measures the difference between oxygen rich and oxygen poor blood flow.
As a result it measures neuronal activity in brain areas and spinal cord.
How do the finding of an fMRI look in someone with depression before and after CBT treatment?
(Specifically looking at the Amygdala and cingulate gyrus)
The Amygdala and cingulate gyrus singals are abnormal before CBT treatment, but normalise after treatment.
There was also increased reactivity in these areas, which led to better outcomes post treatment.
Briefly describe the principles of PET (positron) and SPET (single photon emission tomography).
What can PET and SPET measure?
Gamma emiting radio isotopes (glucose or oxygen normally)
The isotopes connect to certain structures in the brain
Cameras detect the emmiting radiation
Computer programmes quantify data.
(PET has shorter half life isotope, and more expensive)
PET and SPET can measure: blood flow, brain activity and receptors of the brain.
Below is a SPET scan of the brain in someone who has and hasn’t got depresison. Can you describe the differences between the two images.
Depression: reduced blood flow, brain activity and/or receptors. This is indicated by the deeper blues seen.
In depression, there is malfunction of the prefrontal areas. The prefrontal cortex is composed of the: VMPFC, LOPFC and DLPFC.
What do these areas stand for? And what are their functions?
VM - ventro-medial [aggression, sexual function, eating]
LO - lateral orbital [assesses risk, regulates affective states]
DL - dorso lateral … prefrontal cortex [executive function and attention/concentration]
