Biological explanations of depression – (Biochemical) The biochemical explanation claims that depression is the cognitive state resulting from imbalances in brain chemistry that can be controlled in many cases by antidepressant drugs known as tricyclic drugs. However, it does not claim these imbalances are genetic in origin – and, indeed, they may be the consequence rather than the cause of some aspects of depression. There are three brain chemicals principally involved. These are noradrenalin, serotonin and dopamine. Post-mortems of depressed people do not show abnormally low levels of noradrenalin.
Many researchers, such as Crow (1985) believe there are two different types of SZ with different underlying pathology. Type 1 SZ is the type of SZ which would be associated with the Dopamine Hypothesis; it involves DA dysfunction, is characterised by positive symptoms and responds well to anti-psychotic medication. Type 2 SZ, however, is the type that is unsupportive of the Dopamine Hypothesis- it is a neurodevelopmental disorder arising from prenatal insults or perinatal insults, characterised by negative symptoms and does not respond well to antipsychotic drugs. The idea of different types of SZ suggests that DA is not the only
However, research findings within the area of genetics and addiction are inconsistent. For example Noble conducted a meta-analysis and found that 48% of severe alcoholics, 32% of less severe alcoholics carried the A1 variant of the DRD2 gene. Several other studies have failed to find a similar link, this places doubt upon the reliability of the explanation and research findings. Neurotransmitters such as dopamine are also linked to addictive behaviour. According to the disease model addictive behaviour is initiated because drugs/alcohol stimulate the reward pathway within the brain which causes dopamine to be
Gottesman & Shield (1972) found that concordance rate for schizophrenia in non-identical twins is approximately 9% whereas for identical twins, the concordance rate is 42%. This supports the biological model as if schizophrenia had nothing to do with a persons gene, the other twin might not have developed schizophrenia. Also, through ‘gene mapping’, Meyer (2001) found that a mutation in a gene called WKL1 was found I people with a particular form of schizophrenia. Brain damage may also be to blame for abnormalities. For example, excessive alcohol and drug abuse can damage the brain and may result in hallucinations or symptoms of mental health disorders such as Korsakoff’s syndrome.
Negative side effect associated with these drugs Side effects include sleepiness, weight gain, slowness, interference in your sex like, an increased chance of diabetes and Parkinsonism like side effects among others. (Royal College of Psychiatrists' © March 2012.) 4. Anxiety Disorder: There are five major classes of anxiety disorders: generalized anxiety disorders, phobic anxiety disorders, panic disorders, obsessive-compulsive disorders, and post traumatic stress disorder (PTSD). (Biopsychology/Pinel/2009) A.
Chlorpromazine is a type of phenothiazine which is a neuroleptic. Chlorpromazine blocks dopamine receptors in the brain and has been shown to have a therapeutic effect on schizophrenic patients and alleviates symptoms. However, it is only effective on the positive symptoms of schizophrenia for example hallucinations and delusions, but does not appear to have any effect on the negative symptoms. Furthermore, only 70% of schizophrenics respond to chlorpromazine which suggests that it is not a complete treatment for schizophrenia. Those who are drug resistant may be offered clozapine which in an atypical drug and has a similar effect to chlorpromazine, reducing positive symptoms and some negative symptoms.
In general, a brain affected by Dementia produces less of some neurotransmitter. which sets off an imbalance in the brain. For Example, In Alzheimer's, Too little Dopamine effects the acetylcholine levels in the body and starts to block receptors , disabling the brain to reach the right signal to the intended brain cell. Amino Acids, Monoamines, Trace amines, Peptides and Gasotransmitters are some of the endogenous chemicals who’s function it is to allow the transmission of signals from one neuron to the next neuron across the synaptic Cleft. Only 100 chemical messengers have been found to date.
The two main neurotransmitters found to be linked to aggressive behaviour are serotonin and dopamine. High levels of serotonin are said to reduce aggression by inhibiting responses to emotional stimuli that might otherwise lead to aggressive behaviour. Low levels are associated with an increase in impulsive behaviour, aggression and even violent suicide. Evidence supporting the importance of serotonin in aggressive behaviour was found in research using vervet monkeys. Raleigh et al (1991) found that if serotonin levels were reduced by altering their diet, there was an increase in aggressive behaviour whereas an increase in serotonin levels resulted in a decrease in aggressive behaviour suggesting the difference in aggression was due to the serotonin levels.
It does not seem to interact with the neurotransmitter adenosine, which known to be important in REM. It seems probable that alcohol’s general depressant properties reduces brain activity that becomes active in REM. Alcohol does inhibit the neurotransmitter glutamate’s entry to NMDA-receptors (one of the brain’s receptors for glutamate) and glutamate is the main excitatory neurotransmitter, so this provides a partial explanation for alcohol’s effect on general brain activity. Sleep-disordered breathing, a dyssomnia affecting millions of people, is made worse by alcohol. There's a connection between obstructive sleep apnea and alcohol consumption.
Discuss some of the issues surrounding the classification and diagnosis of schizophrenia Classification is a scientific way of putting similar things into certain categories and diagnosis is a way to identify illness by signs and symptoms. There are many issues when it comes to the diagnosis and classification of schizophrenia as it is a complicated disorder that affects around 1% of the population and has many different symptoms. Diagnosing any mental illness can be very difficult as there is a lot to take into consideration and the final decision can only be based on symptoms. Mental illness cannot be tested like normal physical illnesses. With things like diabetes, cancer and so on, the illness can be diagnosed by scans or blood tests.