People who attribute mental illness to brain disease or genes tend to blame affected people less, but see them as more hopeless and dangerous. lauren rushing/Flickr, CC BY-NC-ND

Depression, schizophrenia and other psychiatric conditions are increasingly linked to abnormalities in the brain and in our genes. Many professionals believe these developments hold the key to better treatments and their enthusiasm has spread. The public now endorses biogenetic (biological and genetic) explanations for mental health problems much more than in previous decades.

One possible side effect of these developments is a reduction in stigma. If the cause of psychiatric misery is in our brain chemistry or our DNA, then the miserable cannot be blamed for their symptoms. Advocates argue that stigma will diminish if we come to see mental health problems as biologically caused diseases, no different from diabetes or cancer.

This is an appealingly optimistic view, linking scientific advance to social progress. Unfortunately, it may also be wrong. Many writers have argued that seeing mental health problems as biogenetically caused diseases increases stigma. Believing that a person has a deep-seated biological defect may lead us to see them as unpredictable, incurable and categorically different from the rest of us.

My colleagues and I recently tried to resolve these conflicting views. We synthesised 53 studies of the links between biogenetic explanation for mental health problems and stigma.

The studies examined several forms of stigma. Some considered whether people were blamed and held responsible for their condition. Some assessed the belief that they were unlikely to recover. Some measured the desire to keep away from them. Finally, some measured the perception that people with mental health problems were dangerous or unpredictable.

Our findings indicate that biogenetic explanations have decidedly mixed blessings. People who attribute mental health problems to brain disease or heredity tend to blame affected people less. However, they are also more pessimistic about recovery, more willing to socially exclude affected people and more likely to see them as dangerous.

Attributing mental illness to genetics and biology is a double-edged sword. martinak15/Flickr, CC BY-NC-ND

One notable example of a biogenetic explanation is the “chemical imbalance” view of depression.

The belief that this condition is caused by inharmonious brain chemistry is now widespread. A recent Australian study found that 86% of people thought “chemical imbalance” was a likely or very likely cause of depression. And it was the most frequently mentioned cause Americans named in another survey.

Seeing depression as caused by a chemical imbalance accords with evidence that abnormalities in brain chemicals accompany the condition. It is also intuitively plausible because medications that alter brain chemistry can be effective treatments. Indeed, the chemical imbalance view fits hand in glove with the growth of antidepressant prescribing.

A recent study suggests that the chemical imbalance view of depression has troubling implications. The researchers interviewed 3,642 German adults and presented them with brief descriptions of a person with depression or two other conditions. They rated how much the person’s problems were caused by ten different factors, including a chemical imbalance, a brain disease and heredity. They also rated how much fear and anger they felt toward the person and how much they would socially accept them.

People who endorsed the chemical imbalance explanation had consistently more negative reactions to the depressed person than those who did not. They were more fearful, angrier and less socially accepting. The same negative pattern held for people who endorsed the brain disease and heredity explanations.

The negative implications of the chemical imbalance view of depression may adversely affect depressed people themselves. Arecent study recruited adults who had experienced an episode of depression. They were given a bogus lab test to determine whether their depression was caused by a chemical imbalance. A saliva sample was taken and purportedly assayed for levels of serotonin, a neurotransmitter.

Half of the experimental participants were told their depression was caused by low serotonin levels and shown an official-looking bar-graph to prove it. The other half, a control group, were told their depression was not the result of a chemical imbalance and given test results to match. All participants then rated themselves on a series of questionnaires.

Participants in the chemical imbalance group blamed themselves as much as their control group peers. They were also more pessimistic about their chances of recovery and less confident of their ability to manage their depression.

Further, only participants in the chemical imbalance group believed pharmacological treatment to be more appropriate and effective than psychotherapy. In sum, the chemical imbalance view led people to feel less hopeful and capable in the face of their problems and more disposed to use medication.

People who attribute their mental illness to a chemical imbalance may be less optimistic about their chances of recovery. minds moving/Flickr, CC BY-NC-SA