Models of psychopathology: diathesis-stress and the cognitive theories of depression

Transcript

RyanA student who dreams of law school gets her admissions test score back. It's low. And she tells her counselor: I don't have the brains for this. It will never change. And it's going to ruin every plan I make.

SoheeA few weeks later, she expects that nothing she does will help. And she becomes depressed.

RyanNow imagine a different student, same score, who says: I was sick the day of the exam. That score was a fluke.

SoheeSame event. Two very different explanations. And according to one major theory, that difference is the whole story.

RyanWelcome to EPPP Prep, the podcast. I'm Ryan.

SoheeI'm Sohee. Today's knowledge statement is about major research-based theories and models of psychopathology. In other words, how do psychologists explain where disorders come from? We'll go from the big perspectives down to specific theories of depression.

RyanOpenStax starts with history. For centuries, psychological disorders were viewed from a supernatural perspective, attributed to a force beyond scientific understanding. People were thought to be practicing black magic, or possessed by spirits.

SoheeAnd the textbook notes that such beliefs are still held in some societies today. Which is worth remembering clinically: a client's explanation of their own distress may come from a very different framework than ours.

RyanThen the biological perspective, which views disorders as linked to biological phenomena such as genetic factors, chemical imbalances and brain abnormalities. OpenStax says evidence from many sources indicates that most psychological disorders have a genetic component.

SoheeAnd the psychosocial perspective emphasizes learning, stress, faulty and self-defeating thinking patterns, and environmental factors.

RyanWhich brings us to the model that ties them together: the diathesis-stress model. It says people with an underlying predisposition for a disorder, the diathesis, are more likely than others to develop the disorder when faced with adverse environmental or psychological events, the stress.

SoheeThe key assumption, in the textbook's words, is that both factors, diathesis and stress, are necessary in the development of a disorder.

RyanTwo details that show up on exams. First, a diathesis isn't always biological. Some diatheses are psychological, like a tendency to think about life events in a pessimistic, self-defeating way.

SoheeSecond, the two trade off. The level of stress needed to produce the disorder is inversely proportional to the level of diathesis. The more vulnerable someone is, the less stress it takes.

RyanNow, how do you separate genes from environment? OpenStax points out that family and twin studies can't completely rule out shared environments, since close relatives also tend to share similar surroundings. Adoption studies help, because children are separated from their parents at an early age.

SoheeOne of the first, by Heston in 1966, followed 97 adoptees over 36 years. Five of the 47 born to mothers with schizophrenia, about 11 percent, were later diagnosed with schizophrenia, compared with none of the 50 control adoptees. That pointed to genes. But a later study added the environment.

RyanAnd here's the research that makes it vivid. OpenStax describes an adoption study by Tienari and colleagues of 303 adoptees. One hundred forty-five had biological mothers with schizophrenia, the high genetic risk group. The other 158 had mothers with no psychiatric history.

SoheeThe researchers also rated the adoptive homes. A disturbed family environment meant a lot of criticism, conflict, and a lack of problem-solving skills.

RyanThe results. High genetic risk plus a disturbed home: 36.8 percent developed schizophrenia or another psychotic disorder. High genetic risk but a healthy home: 5.8 percent. Low genetic risk, disturbed home: 5.3 percent. Low risk, healthy home: 4.8 percent.

SoheeSo genes alone didn't do it, and a hard home alone didn't do it. The combination did. The textbook says this supports a diathesis-stress interpretation: both genetic vulnerability and environmental stress are necessary, and genes alone don't show the complete picture.

RyanLet's pause and think. A psychologist explains to a client that his strong family history of depression didn't lead to an episode until he lost his job and his marriage ended in the same year. A coworker went through the same layoff and a divorce that year, but had no such family history, and didn't become depressed. Which model is the psychologist describing?

SoheeDiathesis-stress. Vulnerability alone didn't produce depression, and the losses alone didn't either. The two together did. An answer that blames only genes, or only stress, doesn't fit.

RyanNow depression specifically. OpenStax says cognitive theories of depression are themselves diathesis-stress models: a cognitive vulnerability, meaning negative, maladaptive thinking, plus stressful life events.

SoheeThe best known is Aaron Beck's, developed in the 1960s. Beck theorized that depression-prone people have depressive schemas, mental predispositions to think about most things in a negative way.

RyanThose schemas carry themes of loss, failure, rejection, worthlessness and inadequacy. They may develop early in childhood after adverse experiences, then stay dormant until stressful or negative life events activate them.

SoheeAnd once active, they're maintained by cognitive biases, errors in processing information about ourselves, that lead us to focus on the negative, interpret things negatively, and block positive memories.

RyanThe textbook's example: a person whose schema centers on rejection might notice another person's frown, read it as rejection, and automatically remember past rejections.

SoheeLongitudinal studies have supported Beck's theory, and cognitive therapies for depression grew out of it.

RyanSecond, hopelessness theory, from Abramson and colleagues. It proposes that a style of thinking that sees negative life events as having stable and global causes leads to hopelessness, and then to depression.

SoheeStable means it's never going to change. Global means it's going to affect my whole life. The healthier alternatives are unstable, it's fixable, and specific, it applies only to this situation.

RyanAnd hopelessness itself is defined as expecting that bad outcomes will happen or good ones won't, and that there's nothing you can do about it. That's our law school student.

SoheeOur practice set has a workplace version too. An engineer is passed over for a promotion and decides he's not leadership material and never will be, and that this proves he'll fail at everything else. Within weeks he expects nothing will turn things around, and he becomes depressed. Same theory.

SoheeThe textbook cites one study of people facing uncontrollable stressors. Over six months, those with high cognitive vulnerability were 7 times more likely to develop depression than those with lower scores.

RyanThird, rumination, first described by Nolen-Hoeksema in the late 1980s to explain the higher rates of depression in women than in men. Rumination is repetitively and passively dwelling on one's depressed symptoms, their meanings and their consequences.

SoheeThoughts like, why am I so unmotivated, I'm never going to get my work done feeling this way. Women are more likely than men to ruminate when sad, and the tendency is linked to more depressive symptoms, a higher risk of major depressive episodes, and more chronic episodes.

RyanAnd one learning model that shows up as a distractor: the two-factor, or conditioning, account. OpenStax describes it for obsessive-compulsive symptoms. First, classical conditioning: a neutral stimulus becomes linked to something that provokes anxiety. Then operant conditioning: compulsions are maintained by negative reinforcement, because they reduce the anxiety.

SoheeSo here's the sorting rule for these questions. Dormant negative schemas from early adversity, awakened by stress, biasing attention and memory? Beck. Explaining a setback as permanent and all-encompassing? Hopelessness theory. Dwelling on one's own symptoms? Rumination. Symptoms learned through classical then operant conditioning? Two-factor.

RyanSecond pause and think, quickly. A client who was often criticized and rejected as a child felt well for years. After a breakup, she notices every frown from coworkers, takes each one as rejection, and keeps remembering past rejections. Which theory?

SoheeBeck's. A rejection-themed schema from childhood, dormant until a stressor activated it, now biasing what she notices, how she reads it, and what she remembers.

RyanLet's recap. Perspectives: supernatural, biological, psychosocial. The diathesis-stress model says both vulnerability and stress are necessary, and the more vulnerability, the less stress it takes.

SoheeThe adoption study: high genetic risk led to psychotic disorders mainly in disturbed homes, 36.8 percent versus 5.8 percent in healthy ones.

RyanBeck: depressive schemas, dormant until stress, maintained by biased attention, interpretation and memory. Hopelessness theory: stable, global explanations lead to hopelessness and then depression. Rumination: passively dwelling on symptoms. Two-factor: classical then operant conditioning.

SoheeAnd here's a thought to carry out of this episode. If a hard exam result left you thinking it will never change and it ruins everything, notice the pattern we covered today. That's a stable, global explanation. A truer one might be: this was one result, and it can change with preparation.

RyanYou're preparing right now. That counts. See you next time on EPPP Prep.

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