S: biological explanation and characteristic Flashcards
what is schizophrenia
a psychotic disorder of the mind that affects how you think, feel and behave. mainly the sufferer will lose a sense of contact with reality
when is schizophrenia diagnosed and who does it affect
most often between the ages of 15 and 35. men and women are affected equally and it affects roughly 1% of the population
who came up with characterising symptoms
Kurt Schneider
suggested characterising the symptoms of schizophrenia as either being positive or negative
what is a positive symptom
any change in behaviour or thoughts, such as hallucinations or delusions. here the word ‘positive’ means the presence of behaviours
what are the positive symptoms
hallucinations
delusions
disordered thinking
definition of hallucinations
perceptions that are unreal. often auditory or visual and so involve seeing or hearing things that aren’t really there. they can be experienced in any sensory modality
example of a hallucination
visual- involves seeing things that aren’t real (objects, people etc.)
definition of delusions
beliefs that are unreal, usually experienced with no evidence to offer in support of the belief
example of delusions
paranoid- may believe they’re being harassed or persecuted. may believe they’re being chased, followed, watched or plotted against (often by their family and friends)
grandiose- individuals believe they are special in some ways
definition of disordered thinking
often evident through examining the speech of those individuals with schizophrenia. the persons thoughts seem to jump from one topic to another for no apparent reason and show no logical flow of discussion
example of disordered thinking
a persons train of thoughts seem to jump from one topic to another for no reason (knights move thinking)
and show no logical flow of discussion (word salad)
what is a negative symptoms
a lack of function that you would not usually expect to see in a healthy person
e.g. people with schizophrenia often appear emotionless and flat. negative symptoms refers to an absence of normal mental functioning
what are the negative symptoms
alogia
avolition
catatonic behaviour
flatness of affect
what is alogia
refers to a poverty of speech. apart from a reduction in the total amount of speech produced people with schizophrenia lack meaning, even simple, short answers can be a problem
example of alogia
you may not talk because you hear voices that tell you not to speak or because you feel nervous or paranoid around other people
what is avolition
occurs when people seem to be indifferent to or unconcerned with the goings on in their surroundings. show little desire to take part in activities (work or social) even if it is something they previously enjoyed
example of avolition
inability to care for personal hygiene or participate in work or recreational activities
what is flatness of affect
where the individual would appear to have no emotion. they may converse without the usual emotional intonation and show little or no facial expressions such as smiling or grimacing
example of flatness of affect
may speak in a dull flat voice and your face may not change
what is catatonic behaviour
issues can range widely from fast, repetitive movements to little or no movements at all. the person with schizophrenia may move for no obvious reason
example of catatonic behaviour
may remain motionless in a rigid posture for hours/days
criteria for diagnosing schizophrenia
patient is assessed against the DSM V criteria. the patient must have experienced 2 of the symptoms and at least one must be positive,
continuous signs of these disturbances must persist for at least 6 months and at least 1 month of active symptoms (may be less if successfully treated
what are the 2 biological explanations of schizophrenia
dopamine hypothesis
structural abnormalities
hero explanation of schizophrenia
dopamine hypothesis
sidekick explanation
structural abnormalities
when was a link between dopamine and schizophrenia first established
dopamine hypothesis
when it was found that a drug developed in the 1950s (L-Dopa) was successful in reducing Parkinson’s symptoms, instead sufferers developed behaviours seen in schizophrenics
what did the dopamine hypothesis initially propose
that individuals with schizophrenia simply produce too much dopamine
research supporting the dopamine hypothesis
Griffith et al. induced psychosis in non-schizophrenic volunteers with the administration of dextro-amphetamine (drug increasing the presence of dopamine in the brain) finding that volunteers demonstrated a generally abrupt onset of paranoid delusions and demonstrate a cold and detached emotional response
why has the dopamine hypothesis been labelled as being too simple
as the drug that reduced the levels of dopamine had little or no effect on those individuals who mainly suffered with the negative symptoms of schizophrenia
explain D2 receptor sites
dopamine hypothesis
Seeman and Lee were able to show the impact of anti-psychotic drugs on this particular receptor. as D2 recpetor sites are found primarily in the subcortical regions of the limbic system, this became the main focus of the dopamine hypothesis
these structures are responsible for functions such as emotion, memory formation and arousal
two pathways linked to schizophrenia
dopamine hypothesis
mesolimbic and mesocortical
explain the mesolimbic pathway
D hypothesis
dopamine is a major neurotransmitter in the mesolimbic pathway. this pathway carries signals from the ventral tegmental area to the nucleus accumbens.
hyperactivity of Dopamine D2 causes over stimulation and therefore contributes to the positive symptoms of schizophrenia like delusions and hallucinations.
how do antipsychotics work in the mesolimbic pathway
D hypothesis
reduce dopamine activity in this pathway and ultimately the positive symptoms of schizophrenia
what is the mesocortical pathway
D hypothesis
dopamine is also a major neurotransmitter in this pathway. this path carries signals from the ventral tegmental area to the frontal lobe. this pathway is essential for emotional responses, motivation and cognition
Davis et al. note that hypo-activity/too little dopamine is evident in the D1 receptor sites of the frontal lobe of many individuals with the cognitive impairments and negative symptoms of schizophrenia
