Consultation session Wednesday P1 Miss Mawdsley

Pairs/groups – prepare an answer to the following question What is the logic behind conducting twin studies? Example? What is the logic behind conducting family studies? Example? What is the logic behind conducting adoption studies? Example?

Gottesman, (1991)

Genetics Is there a genetic link between SZ and inherited genetic material? How do we show evidence for this? 1 Family studies Instances of SZ in families If one person in the family has been diagnosed with SZ how many other members of their family have also been diagnosed with Sz? The chance of developing the disorder will increase, the closer our genetic link to that individual (e.g. Mother and daughter = close and daughter and grandparent is not as close) e.g. Kendler (1985) has shown that first degree relatives of those with schizophrenia are 18 times more at risk than the general population.

Twin studies Compare the rates of diagnosis between identical twins (MZ) and non identical twins (DZ). MZ twins are 100% genetically identical where as DZ twins are only 50% identical. If SZ has a genetic component MZ twins should show a higher concordance rate that DZ twins Gottesman (1991) MZ twins 48% risk and DZ twins 17% vs grandchildren 5% In part genetic Not entirely genetic – as they share 100% DNA it would be 100% risk of developing SZ So it is possible that genetics do not cause SZ but the do provide a predisposition to developing it.

Check your understanding – Twin Studies How do the findings compare to the probability of a random member of the general population suffering from schizophrenia? What should concordance be for MZ twins if genetics was the only explanation? Is there another explanation for high concordance amongst family members, particularly identical twins? What about those people diagnosed with the disorder but who have no relatives suffering from it? Why is concordance for MZ twins always higher than that for DZ twins? If diagnostic criteria has changed over time how will it affect the research findings?

E.g. parent who has SZ puts their child up for adoption Adoption studies E.g. parent who has SZ puts their child up for adoption That child is brought up by a different family Child develops SZ (it can be argued that this is down to genes inherited from the mother and not environmental factors) However due to social causation we know that a predisposition is more likely and that the environment can still play a role in the triggering of SZ Finnish Adoption Study (Tienari,1969) identified adopted offspring of biological mothers who had been diagnosed with schizophrenia (112 index cases), plus a matched control group of 135 adopted offspring of mothers who had not been diagnosed with any mental disorder. Adoptees ranged from 5-7 years at the start of the study and all had begun separation from their mother before the age of 4. The study reported that 7% of the index adoptees developed schizophrenia, compared to 1.5% of the controls -this suggests genetics play a role in the development of schizophrenia.

Using twin, family and adoption studies explain the concept of genetic links between SZ and inherited genetic material (4 -6 marks)

Molecular genetics Can a specific gene be identified? McGuffin and Stuart (1980’s) HLA gene, a gene important in the body’s immune system was associated with Schizophrenia but no further research supported this. Hong (2001) TPH gene (involved with the production of an enzyme – tryptophan hydroxylase) They found that the variations in the TPH gene was significantly more common in Chinese patients with SZ than in Chinese controls.

Sekar et al. (2016) analysed 100,000 human DNA samples from 30 different countries. They identified a gene called complement component 4 (C4), which is part of the immune system. Genetic analysis of 65,000 people found that those who had particular forms of the C4 gene showed higher risk of developing schizophrenia. The human brain normally undergoes synapse pruning during adolescence. This is normally a good thing because it's part of learning: the brain 'prunes' under-used or damaged connections to make space for new ones (this is an example of "use it or lose it" going on in the brain). C4 plays a role in pruning synapses but excessive pruning could lead to the symptoms seen in schizophrenia. Test mice with increased levels of C4 activity lost more brain cells as they matured. This would explain why schizophrenia symptoms appear after adolescence and why the brains of people with schizophrenia have a thinner cerebral cortex with fewer synapses than healthy brains. https://youtu.be/n1loGPMk-_Y Further info: https://www.nytimes.com/2016/01/28/health/schizophrenia-cause-synaptic-pruning- brain-psychiatry.html?_r=2

Using the two previous slides- explain how molecular genetics can help explain schizophrenia (4 marks)

Diagnosing SZ and OCD using DSM See infographic.

Case 1 Carl's mother has noticed some changes in his behaviour in the last few weeks. He has been talking in a confusing way where it is difficult to follow his train of thought as he jumps from topic to topic. He also seems to find it hard to express emotion as we won't smile, laugh, or show anger etc. Could Carl receive a diagnosis based on this information? Justify your answer.

Case 2 For the past 8 months Kay has been feeling increasing worried that aliens may be trying to abduct her and her family. Due to this belief she has been acting in a way that worries her family. She has fixed an Antenna on the roof of the house covered in foil as she believes this will 'throw off the signal". In the last few days she was admitted to hospital as she tried to remove a chip that she believed was inserted secretly under her skin. Could Kay receive a diagnosis based on this information? Justify your answer.

Case 3 Caroline is now 51 years old and has obsessions of harming people by spreading her “bad energy” which is experienced by dust on her hands and in her mouth. To prevent harm coming to others she mentally “vacuums” the dust, creates mental protective barriers around nearby people and avoids touching others for fear of transmitting her bad energy. Although she experienced some obsession and compulsions as a child, they got much worse following several stressful life events four years ago. Could Caroline receive a diagnosis based on this behaviour?

Case 4  Isabel is intelligent but she is falling behind at university because she is late or absent. These changes have only become apparent in the last weeks. Some of her friends believe she may have been taking illegal substances at the weekend. She gets up at 5.00am hoping to get to university on time. The next three hours are spent taking a long shower followed by changing clothes repeatedly until it “feels right”. She finally packs and repacks her books, opens the front door and prepares to walk down the front steps. Isabel goes through a ritual of pausing on each step for a particular length of time. Even though she recognises her thoughts and behaviours are senseless, she feels compelled to complete her rituals otherwise something terrible will happen. Could Isabel receive a diagnosis based on this behaviour?

SZ diagnosis using DSM vs ICD Use the infographic and the online ICD system to compare the classification SZ diagnosis using DSM vs ICD Similarities Differences

OCD diagnosis using DSM vs ICD Use the infographic and the online ICD system to compare the classification OCD diagnosis using DSM vs ICD Similarities Differences

General comparisons between ICD and DSM classification systems Term Similarly Whereas On the other hand