Avoidant Personality Disorder


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(Treating Anxiety Disorders may help depression).



Info on neurotransmitters from http://www.csuchico.edu/psy/

Dopamine (DA) is a neurotransmitter which is involved in 
many behaviors; as examples:

One of the most significant findings of the last decade
 has been that of the association between the release 
of dopamine in the brain and reward or reinforcement. 
Animals will push levers to deliver electric stimuli to
 their brains if those stimuli cause the release of 
dopamine. Also, cocaine, opiates, and alcohol produce 
rewarding effects in part due to their abilities to 
promote the release of dopamine.

Parkinson's Disease (PD) is accompanied by a selective
destruction of dopamine neurons in the substantia nigra
of the midbrain which send their axon terminals to the 
striatum which is involved in motor control. PD is treated
with L-dopa which is a precursor for the production of 
dopamine in the brain. The discovery that fetal brain 
cells can be transplanted to the human brain to repair 
the damage of Parkinson's Disease has launched a bioethical
debate in the scientific community and world at large. 

Schizophrenia is treated with drugs which block the
binding of dopamine to its postsynaptic receptor 
sites. The better the drug is at blocking dopamine, 
the better it is at reducing the schizophrenia. The 
dopamine hypothesis of schizophrenia is that there 
is excessive dopamine stimulation in the frontal 
lobe due to a combination of genes and some as yet 
unknown aspect of the environment such as a perinatal virus or toxin. 

Serotonin (5HT) is a neurotransmitter which is involved 
in many behaviors; as examples: 

Human mood disorders (depressions) are effectively 
treated with drugs which specifically block the 
reuptake of serotonin into the presynaptic axon 
terminal, for example fluoxetine (Prozac). The 
resultant enhanced serotonin activation brings 
about a cascade of events ultimately resulting 
in a reduced sensitivity of presynaptic autoreceptors 
for serotonin and reduced serotonin synthesis. 
This suggests that neurotransmitter dysregulation 
may be involved in depressive disorders.

Human OCD (Obsessive Compulsive Disorder) is 
effectively treated by serotonin reuptake 
inhibitors suggesting that this condition 
may also be due to dysregulation in serotonin synapses.

Human violence, aggressive behaviors, 
and suicide have all been associated 
with reduced levels of serotonin in the brain. 

Sleep onset latency is reduced with tryptophan which 
is the amino acid needed by the brain for the synthesis 
of serotonin. This finding suggests that serotonin 
may play a role in sleep induction. Grandmother's 
suggestion to drink a glass of warm milk before 
sleep may be sound, since milk is a good source 
of tryptophan.

Some drugs which distort perception (e.g. LSD) 
bind to one type of serotonin receptor
(5-HT2). Serotonin synapses are abundant 
in the cerebral cortex making it likely 
that they are involved in the processes 
of perception in some way. 

Norepinephrine (NE) is a neurotransmitter 
involved in many behaviors; as examples:

Norepinephrine plays a role in attention and 
general arousal level. Waking behavior is 
enhanced by drugs which activate norepinephrine 
systems while REM sleep (dream sleep) occurs when 
norepinephrine systems are at their lowest level of activity.

Brain norepinephrine is depleted in states of
chronic stress and this depletion may contribute 
to the harmful effects of stress. Exercise of a 
chronic aerobic nature appears to enhance the 
brain's ability to deal with stress and protect 
it from depletion of norepinephrine.

Norepinephrine is involved in mood states. 
Some of the drugs which are used to treat 
depressive disorders (tricyclic antidepressants) 
block the reuptake of norepinephrine at the synapse.

Norepinephrine is also released as a hormone 
from the adrenal glands during stress. This 
hormonal norepinephrine acts as an amplifier 
for the sympathetic nervous system "fight or 
flight" response and is an important aspect 
of adaptive behavior in times of challenge. 
Interestingly, this hormonal norepinephrine i
s important for learning and the formation of memory. 

Amino Acids - Some Examples:

GABA (gamma-aminobutyric acid): GABA is the main 
inhibitory neurotransmitter in the brain. Its 
actions, which are anxiety reduction, are mediated 
by the entry of chloride into a cell when GABA 
binds to its postsynaptic receptor site. Drugs 
such as Valium which act as anxiolytics (anti-anxiety) 
produce their effects by enhancing the effects 
of GABA at the synapse. The brain produces 
substances which enhance anxiety (beta-carbolines) 
as well as substances which reduce anxiety 
(e.g. allopregnanolone). All of these substances 
seem to modify the GABA receptor in the brain 
to produce their effects.

GLU (glutamate): Glutamate is the main excitatory 
neurotransmitter in the brain. Its actions are 
mediated at two types of receptor sites (NMDA and 
AMPA). At the NMDA receptor glutamate binding will 
cause calcium to flow into a neuron (but only in 
large amounts when the AMPA receptors are also 
activated). These receptors are involved in the 
process of memory formation in the brain. Curiously, 
glutamate is also involved in a "suicidal" response 
when the brain is damaged such as in a stroke. 
Excess glutamate is neurotoxic and neurons are 
killed by the excessive calcium which enters 
the cell due to glutamate binding. It is 
glutamate which is produced excessively in 
ALS (Lou Gherig's Disease) and which causes 
the death of neurons in the spinal cord and brainstem. 

Peptides - Some Examples:

Endorphins/Enkephalins: Endorphins and enkephalins 
are endogenous opiate peptide neurotransmitters 
found in a variety of places in the brain 
(limbic system, midbrain). They are also 
produced by the pituitary gland and released 
as hormones. They are involved in pain reduction, 
pleasure (they enhance the release of dopamine), 
and hibernation as well as a number of other 
behaviors. Opiates of the world (natural and synthetic)
all work to alter behavior because of their 
ability to bind to endorphin and enkephalin 
receptors in the brain.

Substance P: Substance P is one of the 
neurotransmitters which mediates the 
experience of pain. It is found throughout 
the pain pathway and its release can be 
blocked by enkephalins.

Neuropeptide Y/Polypeptide YY: NPY and 
PPYY are neurotransmitters found in the 
hypothalamus, particularly the paraventricular 
nucleus. These neurotransmitters bring about 
excessive food intake and fat storage and have 
been linked with human eating disorders. 

Some other neurotransmitters:

Acetylcholine (ACh) is a neurotransmitter 
which is involved in many behaviors; as examples:

Movement: Each time you move a muscle it 
is because acetylcholine has been released 
from a neuron to activate muscle fibers. 

Acetylcholine releasing neurons in the pons 
are very active in REM sleep (dreaming),

Learning and memory are blocked by drugs which 
impair the synthesis and release of acetylcholine, 
and in certain cases choline (an amino acid 
necessary for the synthesis of acetylcholine) 
has been found to improve learning and memory. 
Alzheimer's Disease is associated with a 90% 
loss in the brain's production of the 
neurotransmitter acetylcholine in the 
basal forebrain and hippocampus. 



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