Abnormal Psychology Flashcards
Prevalence rates and disorders
Lifetime prevalence of MDD is higher in high-income countries than low income countries. The risk for women has also been consistently found to be twice as much as men. Age of onset varies from adolescence to early forties, but the median age onset is mid 20s with a depressive episode lasting 3-4 months. However, it is difficult to know the true prevalence because of the classification system in use, reporting bias, cultural stigma, and cultural variation in the expression of symptoms.
Kessler and Bromet (2013)
Aim: compare prevalence of depression across cultures
Procedure:
- review of publications containing epidemiological data (surveys)
Findings:
- MDD is a commonly occurring disorder in all countries surveyed
- lifetime prevalence estimates of MDD ranged from 1% (czech republic) to 16% (USA)
- age of onset does not vary, regardless of socioeconomic status and is 25 years
- womens risk for developing MDD is also consistent across cultures and is twice of men
Conclusion:
- prevalence rates of MDD considerably vary across cultures
- this may be due to factors including the classification system in use, the survey used to establish symptoms, etc
Furnham and Malik (1994)
Aim: investigate cross-cultural beliefs about depression
Procedure:
- 152 female subjects in 2 age groups: young and middle aged
- half of the participants are native British and other half were asian origin
- participants filled out questionnaires about their symptoms of mental illness and their beliefs about depression
- responses were compared across age groups and culture
Findings:
- perception of depression differed among asian and British participants
- asian participants believed that depression is temporary and can be fixed by having a job outside the home
- differences were less pronounced in the groups of younger women
Conclusion:
- cultural differences influence the rate at which disorders are reported
Explanations for disorders - biological
- genetic ethology of depression can be estimated from data obtained in twin studies, family studies, adoption studies, etc. In using twin studies, it has been demonstrated that heritability of depression was significantly higher in women (42%) than in men (29%)
- Using molecular genetics, it has also been suggested that a functional polymorphism is 5-HTT (serotonin transporter gene) determined how strongly stressful life events will influence depressive symptoms. Individuals with a short allele of the 5-HTT were more likely to react to stressful life events with depressive symptoms
- Neurochemistry: depression has been linked to low levels of serotonin and imbalance in brain chemistry
Cognitive factors that influence depression
Beck (1997) identified 3 elements of depression and its impact on automatic thoughts: the cognitive triad) negative thoughts about the self, world, and future), negative self schemata (always blames oneself), and faulty thinking patters which lead to irrational conclusions
Kendler et al (2006)
Aim: compare genetic heritability of MDD in men and women
Procedure:
- over 42,000 twins located through the national Swedish Twin Registry
- birth cohort spanned 60 years, which enabled researchers to compare results across generations
Findings:
- genetic heritability of depression showed to be 38%, very similar to previous studies which found it to be 37% on average
- no evidence was found that shared environment was of any importance as a factor of developing MDD
Conclusion:
- MDD was moderately heritable
Caspi et al (2003)
Aim: investigate the relationship between stressful life events and depression in individuals with different functional polymorphisms (alleles) of the 5-HHT gene
Procedure:
- over 1,000 children from New Zealand
- sample was divided into 3 groups: short alleles, one short and one long, and 2 long
- longitudinal study in which participants were assessed every 2 years between the ages of 3 and 25
- participants recorded stressful life events in a life history calendar that includes factors such as health, employment, and relationship stressors
Findings:
- there was no difference between the 3 groups in the number of stressful events they experienced
- however, found that participants with a short allele (s/s or s/l) reacted to stress life events with more depressive symptoms
Conclusion:
- 5-HTT does not influence exposure to stressful life events, but influences an individuals reaction to these events
Cognitive explanations for disorders
- cognitive triad: negative beliefs about the self, the world, and the future
- negative self-schemata: individuals begin to see their own fault in everything that happens to them, even If they cannot control it
- faulty thinking patterns: biases in thinking lead to irrational conclusions
Alloy, Abramson, and Francis (1999)
Aim: investigate whether a particular style (positive or negative) in freshman is associated with the development of depressive symptoms
Procedure:
- participants were divided into 2 groups based on results of a questionnaire given (low risk vs. high risk for depression)
- participants with a negative cognitive style, which believed that negative events were catastrophic, were placed in the high risk group
- followed longitudinally for 5.5 years and assessments included self report measures and structured interviews
Findings:
- during first 2.5 years of follow up: high risk freshman were more likely to develop MDD than low risk (17% to 1%)
Conclusion:
- negative cognitive styles may influence the development of MDD
Caseras et al (2007)
Aim: investigate whether attention to positive vs. negative stimuli is different in depressed vs. non depressed participants
Procedure:
- using a questionnaire, participants were divided into 2 groups: depressive symptoms vs. non depressed
- shown a series of neutral stimuli. Each was presented for 3 seconds
- using eye-tracking tech, researchers measured which picture the participant looked at initially and the duration of looking at the initial picture before switching
Findings:
- participants with depressive symptoms demonstrated a bias in maintenance of attention to negative pictures, but no differences were found in initial orienting
Conclusion:
- negative attention bias potentially is one of the mechanisms of MDD
Sociocultural explanations for disorders
- stressors in environment (having 3 or more children, lack of intimate relationship, lack of employment, and loss of loved one)
- resources available for coping with stressors
- cultural factors: in traditional societies where depression is stigmatized, may cause people to misinterpret their symptoms and either fail to report them (reporting bias) or report them as symptoms of physical illness (somatization)
Kivela et al (1996)
Aim: investigate the extent to which various social factors predict occurrence of depression in elderly populations
Procedure:
- clinical study of depression in old age was completed in Finland with 1500 participants, aged 61 or older
- participants were divided into 2 groups: depressed vs non depressed
- questionnaires were used to measure social variables and occurrence of certain life events
Findings:
- compared to non-depressed men, it was revealed that the following were predictors of depression in men: poor relationship with spouse and neighbour, and loss of mother while under 20 years of age
- compared to non depressed women, it was revealed that the following were predictors of depression in women: loss of father while under 20 years of age, worsening relationship with neighbour, and an alcohol problem of close person
Conclusion:
- social factors and changes in social ties may predict onset of depression at old
Rosenquist, Fowler, and Christakis (2011)
Aim: investigate if depressive symptoms can be spread from person to person
Procedure:
- questionnaire for measuring depression was administered 3 times between 1983 and 2001
- data was computerized, with a focus on levels of depression in each individual as well as friends, relatives, neighbours, and co-workers
Findings:
- there was a significant correlation in depressive symptoms up to 3 degrees of separation away
- participants were 93% more likely to be depressed if a person directly connected to was depresed
- this came down to 37% more likely to be depressed if a person within 3 degrees of separation was depressed
Conclusion:
- depression in 1 person may cause depression in people the individual is socially connected to
Prevalence rate and disorders studies
Kessler and Bromet, Furnham and Malik
Biological explanations for disorders studies
Kendler et al, Caspi et al
