GUEST POST
CLINICAL
DEPRESSION
Clinical
Depression is a common illness, different from ordinary sadness, which is a normal reaction. It
can affect anyone, including doctors like myself, and indeed I suffered from
this, during my illness. It is not a weakness.
It may occur spontaneously in vulnerable
individuals, like someone with a family history of depression. Severe
stress or traumatic events in childhood, may also make an individual vulnerable
to developing depressive illness, later on in life. Recent research has shown
that this could be due to the effect of stress hormone cortisol, on the
developing brain. Severe stress or loss events (like losing a family member)
can cause (precipitate) it. In my case the brain infection I suffered, affected
the limbic/emotional brain (see below).
Emotions, and certain
behaviours are
controlled by the limbic (emotional) brain. This is like a circuit
comprising of connections from the brain stem (stem of the brain), to the front
part of the brain (prefrontal cortex, the part in front of the motor cortex),
then to the medial (inner side) of the temporal lobe structures like amygdala
and hippocampus. In my case, it is the left prefrontal cortex, which is next to
the motor cortex (which caused weakness on my right side) and the speech (Broca’s)
area.
There are different theories about the biological
causes of depression within the brain. However, there is a lot of clinical, and
research evidence that depression is associated altered levels of chemicals
(neurotransmitters) that control emotions, and
behaviours. The two
main chemicals (neurotransmitters) being serotonin and noradrenaline (also
known as norepinephrine). These chemicals are made by the brain from the food
we eat, like bananas (I asked my daughter to get me bananas during my recovery
phase). Emotions and behaviours like mood, sleep, appetite, enjoyment,
concentration, short-term memory, energy, and some forms of thinking are
controlled by these chemicals.
There is both clinical, and research evidence that
these chemicals become imbalanced, causing symptoms of clinical depression
including persistent low mood, tearfulness, poor sleep, lack of enjoyment, poor
concentration, short term memory, reduced interest in things, poor appetite,
feeling negative (like focussing on past traumatic or unhappy events, or being
emotionally affected by current sad events) up to including suicidal thoughts. (Recent research has shown that amygdala become very active in clinical
depression, negative traumatic past events tend to re-surface and the
individual becomes pre-occupied with these events, feels hopeless,
worthless, and has suicidal thoughts, and these symptoms are reversed by effective
treatment of depression). These
symptoms tend to be worse in the morning (diurnal variation, possibly related
to high levels of the stress hormone cortisol) and can improve later on during
the day. Like in my case, my mood was worse in the morning. “I was emotional and found myself crying
without a moment’s notice.”
As depressive illness can affect confidence,
energy, motivation, concentration, short term memory, level of functioning is
impaired (the ability to carry out activities of daily living, even to the
point of being unable to work, socialise or to go to school). The World Health Organization
(WHO) found out in a study (1990), comparing medical illnesses, that depression
was four in the league table, as a cause of health-related disability. They
estimated that by 2020, it will rank second to heart disease!
Current research has shown that severe stress
increases the levels of stress hormone cortisol, which in turn reduces
serotonin, noradrenaline, and brain-derived neurotrophic factor (BDNF, also
known as brain fertilizer, which protects against cell death by cortisol),
in the brain, causing depression.
Antidepressants work by increasing these chemicals/neurotransmitters
(improving symptoms, and level of functioning), and may protect against severe
stress causing depression. Psychological treatment like cognitive behavior
therapy (CBT), is also effective in depression, especially in combination with
antidepressants. Current guidelines recommend psychological treatment for mild
to moderate depression, and antidepressant medication, plus psychological
treatment for moderate to severe depression.
Dr Patrick Mbaya MD FRCPsych.
www.drpatrickmbaya.com
References:
Duman Ronald. Depression: a cause of neuronal life and
death. Biological Psychiatry, 1 August 2004, vol.56:140-145
Global Burden of Disease, World Health Organization,
1990.
Mbaya Patrick. My Brain Is Out Of Control. Author
House. September, 2016
Shimizu Fiji et al. Alterations
of serum levels of brain-derived neurotrophic factor (BDNF) in depressed
patients with or without antidepressants; Biological Psychiatry, 1 July
2003,Vol 54(1): 70-75
Stahl Stephen M. Essential Psychopharmacology,
Neuroscientific Basis and Practical Applications. Second Edition. Cambridge University Press.
Stress and Plasticity in Limbic System, Robert M.
Sapolsky; Neurochemical Research, Vol. 28, No. 11.
Dr. Patrick Mbaya is a medical doctor specializing in psychiatry. He is a consultant psychiatrist and honorary clinical lecturer in psychiatry at the University of Manchester, United Kingdom. He has a special interest in mood and addiction disorders.
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