Studying Schizophrenia: Classification and Diagnosis Part II

Here, at last, is part II. Sorry it took so long. Hope everyone has had a good new year so far. Anyway, here we go.


The last post looked at the positive symptoms of schizophrenia, if you wish to refresh your memory click here. This post will look at the negative symptoms, which can be found in the DSM-IV-TR.

Negative Symptoms

These include: Affective Flattening, Alogia and Avolition.

-Affective Flattening This is the reduction in the range and intensity of emotional expression, which can include facial expression, intonation, eye contact, and body language.

Affective flattening

-Alogia or poverty of speech is characterized by the lessening of speech fluency and productivity. This is thought to reflect slowing/blocked thoughts.

Alogia

-Avolition This is the reduction/inability to initiate and persist in goal-direct behaviour.

That's it for the diagnosis. If you're interested in the biological or psychological explanations or theories for schizophrenia stick around and I'll be sure to post again soon. Thank You.

Studying Schizophrenia: Classification and Diagnosis Part I

Diagnostic Criteria: Positive and Negative Symptoms


     The symptoms of schizophrenia are typically divided into two groups:

• Positive symptoms - these are symptoms that appear to reflect an excess/distortion of normal functions,
• Negative symptoms - these are symptoms that appear to reflect a loss/lack of normal functions, which often persist during periods of low/absent positive symptoms.

Under the DSM-IV-TR, the diagnosis of schizophrenia needs at least one-month duration of two or more positive symptoms. However, this does exclude positive symptoms brought upon known organic causes e.g. drugs or brain tumour.

Positive Symptoms

These include: Delusions, Hallucinations, Experiences of Control and Disordered Thinking

-Delusions These are bizarre beliefs that seem real to individual, but are not real. Sometimes these delusions can be paranoid (e.g. fear of persecution), involve inflated beliefs of the individuals power/importance (e.g. 'I am the King of Spain'), and can be delusions of reference (involving the belief that behaviour/comments of others e.g. radio/TV broadcasts are meant for them alone.)

An example of a delusion of reference

-Hallucinations These are bizarre, unreal perceptions of the environment that generally auditory, but can be visual, olfactory or tactile.

Different types of hallucination, including: auditory, visual, olfactory and tactile

-Experiences of Control This is where the individual may believe that they are under control of an alien force that has invaded their mind.

Experiences of Control

-Disordered Thinking This is the feeling that thoughts have been withdrawn or inserted into the individuals mind. In some cases the individual may believe that their thoughts are being broadcast-ed so that others can hear them. Incoherent or loosely associated speech is used as an indicator of thought disorder (e.g. 'hench...bench...tench...that's a type of fish!')

Disordered Thinking

I hope that you have found this useful. Part II of this blog will be coming soon, which will be on the negative symptoms of schizophrenia. Until then Merry Christmas, Feliz Navidad, Joyeux Noel, Gajan Kristnaskon, Nollaig Shona Dhuit.

Studying Schizophrenia: Genetic Factors

Genetic Factors and Schizophrenia


Genetic Factors: It has been known for a long period of time that schizophrenia runs in families. This could be explained by families sharing the same disadvantaged environment. However, research evidence suggests that genetic factors are important. Such evidence comes from three major sources:

• family studies,
• twin studies,
• and, adoption studies.

Evidence from family studies

First-degree relatives share (on average) 50% of their genes, and second-degree relatives share 25%. Studies compare rates of schizophrenia in relatives of diagnosed cases compared to relatives of controls to investigate the genetic transmission of schizophrenia. Now there is considerable amounts of evidence that implies that the closer the biological relationship, the greater the risk of developing schizophrenia (or a related psychotic disorder).

Evidence from twin studies

Twin studies offer another way of establishing genetic links, this is done by comparing the difference in concordance rates for identical (mono-zygotic) and fraternal (di-zygotic) twins. Both share the same environment, but only MZ twins have identical genetic make-up. Multiple studies have been conducted and all show a higher concordance rate in MZ twins than in DZ twins. To distinguish genetics conclusively from the environment, researchers have searched out MZ twins reared apart where at least one twin has been diagnosed with schizophrenia. Obviously, in this case there are few in number and an added problem is that one of the reasons for separation may have been a problem in the family. However, even in the rare cases where MZ twins are reared apart, they still share the same environment in their mother womb, therefore the contribution of environmental factors can't be entirely discounted.


Gottesman and Shields (1982) used the Maudsley twin register and found that 58% of MZ twin pairs were concordant for schizophrenia. If the genetic hypothesis is correct, then the children of a non-affected dischordant MZ twin should still be at high risk.

Evidence from adoption studies

A more competent way of separating out the effects of environment factors is to analyse adopted children who later develop schizophrenia and compare them with their biological and adoptive parents.
The Finnish Adoption study (that began in 1969 by Tienari) had identified 'adopted away' offspring of biological mothers who had been diagnosed with schizophrenia, plus a matched control group of 135 'adopted away' offspring of mothers who had not been diagnosed with any mentla disorder. The study reported that 7% of the index adoptees developed schizophrenia, compared to 1.5% of the control group.
The Danish Adoption study (Kety et al, 1994) took a national sample from across Denmark. The results where that high rates of diagnosis for chronic schizophrenia in adoptees who biological parents had the same diagnosis, on the contrary of the adoptee being adopted by 'healthy' parents.


From these case studies, it is indicated that there is a strong genetic link for schizophrenia. A criticism for these longitudinal studies, however, is that diagnostic criteria for schizophrenia is constantly being changed and updated.

Studying Schizophrenia

Is schizophrenia genetic? 

    The graph on the right shows that first degree relatives of schizophrenics are at a higher percentage risk of developing/having schizophrenia than those who are second or third degree relatives. Identical twins show the greatest percent at risk, implying that if a twin is diagnosed with schizophrenia the other twin is 60% likely to have schizophrenia as well. The graph presented supports the argument that schizophrenia is mainly genetic (or nature). However, there is some debate that schizophrenia is note purely genetic (nurture). An example of this is the Double-blind theory proposed by Bateson et al.

Bateson et al. (1956) suggested that children who frequently received contradictory messages from their parents were more likely to develop schizophrenia. For example, if a mother tells her child that she loves them, yet at the same time she turns her head away in disgust, the child receives two conflicting messages about their relationship on different communicative levels, one of them being affection on a verbal level, and the other of animosity on the non-verbal level. This results in the child’s ability to respond to the mother is incapacitated by these contradictions because one message invalidates the other.  These interactions prevent the development of an internally coherent construction of reality, and over time, this manifests itself as schizophrenic symptoms (e.g. withdrawal and flattened effect).

 

The Dopamine Hypothesis

      Dopamine is one of the many different neurotransmitters that operate inside the brain. The dopamine hypothesis states that impulses from the neurons that transmit dopamine fire too easily/often, which lead to the characteristic symptoms of schizophrenia. Schizophrenics are thought to have abnormally high numbers of D₂ receptors on receiving neurons, which then results in more dopamine binding and therefore more neurons firing. 

Here is an example of the key role played by dopamine in schizophrenia:

Low levels of dopamine activity were discovered in people who suffer from Parkinson’s disease, a degenerative neurological disorder.  It was found out that people who had been taking the drug known as ‘L-dopa’ (to raise the levels of dopamine) were developing schizophrenic type symptoms.

Thanks for reading. I hope this blog inspires you to read more. Remember- ignorance isn't bliss.