Depression: Biological or Psychological?

Just about everyone believes that depression—the #1 psychiatric diagnosis—is explained in the same way as physical illnesses; that is, that depression, too, is of genetic/physiological origin.

Many people also believe the psychiatric drugs prescribed to treat depression are effective because they correct a verified biological causation for depression, a chemical imbalance in the brain.

These beliefs have been shaped by NIH’s National Institute for Mental Health (NIMH) and by psychiatrists, whose opinions regarding mental health care are trusted by the public.

NIMH and psychiatrists have not always explained depression to be genetic (as “running in the family”). For most of the 20th century, depression was viewed to be of psychological origin. NIMH regarded depression as a rare, non-recurring disorder, with a very favorable prognosis. It was treated psychologically, not medically. The head of NIMH’s Depression Section, Dean Schuyler, stated that most depressive episodes “will run their course and terminate with virtually complete recovery without specific intervention.” NIMH concluded, “Depression is, on the whole, one of the psychiatric conditions with the best prognosis for eventual recovery with or without treatment.” A psychiatric textbook (Silverman, C., 1968, The Epidemiology of Depression) reported that just 6% of the U.S population was diagnosed as depressed during their lifetime.

Today’s belief that mental disorder is of genetic/physiological origin best treated medically with antidepressant drugs was advanced in 1980 when the American Psychiatric Association published psychiatry’s third edition of their diagnostic manual of mental disorders, DSM-III. The manual’s publication was accompanied by psychiatry’s chemical imbalance theory of mental disorder and advocacy of medical treatment of depression by prescription of antidepressant drugs. Psychiatry’s rejection (including by NIMH) of the previous psychological viewpoint regarding depression (and other mental disorders) is referred to as psychiatry’s “medical revolution.”

Five times as many people now are diagnosed as depressed during their lifetime (primarily women). Tens of millions take these drugs every day. Moreover, depression now has a poor prognosis, with frequent relapses.

In assessing what to make of this changed conceptualization of depression and the much worse treatment outcome, it is important to understand the significant difference in the scientific credibility of the claims being made by psychiatrists compared with those of doctors who treat physical illnesses. Whereas an abundance of scientific research attests to the biological causation and the medical treatments of numerous physical illnesses, this is not true of psychiatric claims. Aside from just a few mental disorders—Down syndrome, dementia, and the organic disorders of alcohol and drug abuse—none of the commonly diagnosed mental disorders, including depression, has been found to be of biological origin. And despite what you may have read or been told, outcome research has not found antidepressant drug treatment of depression to be very effective.

This is not for want of trying. With regard to the causation of depression, NIMH has spent many tens of billions of research dollars over the course of more than fifty years seeking to find evidence for a genetic, neurological, or physiological basis for depression. Their efforts have failed. When biological evidence (genetic evidence) is found it is quite weak, providing insufficient accounting for the disorder.

As a prime example related to causation, in the early 2000s, a group of psychiatrists claimed they were ready to provide a new diagnostic manual (DSM-5) which would diagnose mental disorders on the basis of brain abnormalities. The American Psychiatric Association appointed them as a task force to implement their claims. Put to the test, they were unable to demonstrate that the mental disorders are biological illnesses. They could not distinguish one disorder from another physiologically, neurologically, or genetically; they could not specify biomarkers for any of the mental disorders; and the kappa statistical values pertaining to the reliability of their diagnoses were even worse than those for DSM-III.

Ultimately, when DSM-5 was published in 2013, the manual retained the descriptive stance adopted for DSM-III, which had ducked specifying any biological causation for the disorders. Robert Spitzer, who headed up the construction of DSM-III, acknowledged he knew of no such evidence apart from the few disorders I cited above. Nonetheless, psychiatrists have used DSM-III ever since to promote this contention that depression is a biological disorder.

With regard to assessments of the value of drug treatments for depression, not only have antidepressant drugs not been found to be very effective treatments for depression, the data indicate that when taken long-term, which is how these drugs most often are prescribed, the outcome is a worsening of depression.

NIMH’s research efforts to demonstrate that antidepressant drugs are of value began with studies of the antidepressant drug imipramine. Outcome studies failed to find the drug to be effective. Measured short term (after three months), patients treated with the drug did not benefit any more than those treated with a placebo. Even worse, when drug effectiveness was measured long-term, after 18 months of treatment (the more meaningful measure), the drug-treated patients received no more benefit than those treated with a placebo; the drug-treated patients had a lower number of weeks being symptom-free; they had higher relapse rates; and a higher percentage of the drug-treated patients sought additional treatment. Most damningly, patients treated with a placebo, and patients not treated at all, fared better than the patients treated with the drug.

Today’s favored antidepressant drugs are the SSRIs. Psychologist Irving Kirsch, who is the leading researcher on the placebo effect, re-analyzed the data submitted by the drug companies to the FDA (of measures taken short-term) that led to the FDA’s approval of the SSRIs as effective treatments for depression. He found that the FDA had erred. His statistical analyses of the data show the drugs qualified as producing a placebo effect, not a drug effect.

Outcome research conducted in other countries on the effectiveness of the SSRIs report results consistent with these findings. The UK’s health department found antidepressant drugs are no more helpful short-term than placebos and much less helpful than placebos long-term. A Swiss study found the long-term outcome for patients treated psychologically was significantly better than those treated with antidepressant drugs (SSRIs) and that patients treated with antidepressant drugs fared worse than those not treated at all.

In 2006, NIMH conducted the STAR*D study in a more concerted effort to obtain scientific substantiation for their beliefs that depression is a biological disorder and that the SSRIs are effective treatments for depression. Enrolling over 4,000 patients who were being treated in clinics across the country, and at a cost of 35 million dollars, the STAR*D study is the largest study ever done to determine the effectiveness of antidepressant drug treatment measured short-term and long-term and to provide evidence for depression having a biological basis.

The study’s results mirrored previous findings. Measured short-term, after a month of SSRI drug treatment, the results were modest (30-35% remission), closely matching what previous drug outcome studies and Kirsch’s re-analysis of the FDA data had found that the SSRIs provide a placebo effect. Measured long-term, after twelve months of treatment (the more meaningful measure of effectiveness), the remission rate was just 3%, agreeing with the negative results found by previous antidepressant outcome studies.

However, these findings are not what STAR*D’s investigators reported for the study. By various means of statistical sleight of hand, they claimed—quite falsely—that the drugs are successful treatments for almost 70% of the patients. NIMH, psychiatrists, and the media have been reporting these as the results of the STAR*D study ever since. They have succeeded in leading the public (and other doctors) to believe these drugs are of great value when that is not at all what the study found. Four publications have documented how these are fabrications, not the study’s findings—a major example of research fraud. The evidence has been detailed in these pages (see Whitaker, R., January, 2025, “Summing up the STAR*D Scandal: The Public was Betrayed, Millions were Harmed, and the Mainstream Media Failed Us All,” Mad in America).

A secondary goal of the STAR*D study was to provide evidence that depression is a biologically heterogeneous disorder successfully treated when patients are prescribed the drug that fits their form of depression, “matching patients with their optimal treatments.” STAR*D’s investigators falsely claim their drug treatment results verify this heterogeneity theory of depression. In fact, when analyzed correctly, the STAR*D data show that it did not matter what drug was prescribed. Every drug produced the same limited effect as every other drug. The data do not support psychiatry’s biological theory that treating patients with drugs having different biochemical actions enhances the outcome.

These negative results should not be surprising. Psychiatry’s justification for prescription of the SSRIs is based on the chemical imbalance theory of depression, that depression is caused by a deficiency in the brain of the neurotransmitter serotonin, and that the SSRIs correct this deficiency. Research conducted by UK psychiatrist, Joanna Moncrieff, which applied five different methods of biological analysis, soundly disposes of this theory. She found no support for the chemical imbalance theory of depression.

Psychiatry’s “medical revolution,” which has shaped the beliefs of doctors and the public into believing depression is a biological illness best treated with antidepressant drugs, is contradicted by scientific testing. Follow-up data show that rather than alleviating depression, psychiatry’s medicalization of depression is contributing to it (see Robert Whitaker’s book, Anatomy of an Epidemic, and Laura Delano’s book, Unshrunk). Quite plainly, psychiatry’s medicalization of depression exists in great contrast to the standards of scientific testing adhered to by researchers studying the cause and treatment of physical illnesses—research standards that have led to successful treatments for so many commonly occurring physical illnesses.

Patients being treated for depression are led to believe in antidepressant drugs by drug company hype, trust in their doctor’s advice, the popularity of taking these drugs, the placebo effect, and misinterpretation by the doctor and the patient of adverse drug effects as a recurrence of depression. Not by biology, not by genetics.

The science that confirms the genetics related to animal behavior originated with the observations of Charles Darwin and Gregor Mendel. Richard Dawkins, the evolutionary biologist, advanced our understanding of how genetic changes occur by pointing out how evolution depends upon an animal’s movements (behaviors) which happen to take advantage of opportunities presented in the immediate environment—a process that plays out genetically over eons.

This principle has generality. It not only explains genetic changes that are biologically determined, including explaining some physical illnesses, it also explains the process of learning, which is determined psychologically. Behaviors that are synchronized with what the environment has to offer are subject to learning because they are reinforced. Importantly, this learning process occurs over days and weeks, not eons.

The science related to human behavior tells us that our behavior, in contrast to lower animals, is primarily a function of learning, not genetics—a psychological process. Mammals evolved with larger brains, expanding their potential for learning. Humans enjoy the greatest advantage. This is not to deny the importance of the biology of the human brain. Our brain houses the substrates necessary for our psychologically determined behaviors to be learned, such as memory functions, the reinforcement system, and our cognitive ability.

Behavioral principles, honed over decades of psychological research, explain how our behaviors are created, how they are shaped and maintained, and how they are ended and replaced. Scientifically sound behavioral research provides the explanation for how the commonly diagnosed mental disorders, including depression, arise as learned dysfunctional behaviors—and how they can be unlearned by making use of the same principles. Mental disorders that cannot be explained biologically can be explained psychologically.

During the 20th century there were two psychological explanations for the causation of depression: psychoanalysis, which was widely-accepted, and behavioral psychology, which was less well-known and whose basic features were still under study. Psychiatrists at that time explained depression and other mental disorders according to Freudian psychoanalytic theory, which holds that depression is caused by unconscious conflicts related to unresolved negative childhood experiences. The theory is speculative, incapable of scientific testing, because case histories are cited for its basis. Case histories do not qualify as science because they are subjective, which limits scientific testing of the theory and of whatever elements in this psychological treatment may be contributing to its success.

However, patients diagnosed as depressed were not treated with psychoanalysis (or with drugs, which came later). Psychoanalysis is a lengthy treatment of several years’ duration—even its abbreviated versions last a year or longer. The prime treatment for depression was relaxation and exercise. As I indicated above, the outcome was quite favorable compared to the outcome found for other mental disorders and off the charts in comparison with today’s results for the diagnosis and treatment of depression. It is easy to speculate that in addition to whatever relevant societal changes have taken place in life experiences since then, the prime contributors to the success of this simple psychological treatment is that patients experiencing normal sadness were not misdiagnosed as depressed as they are now, and those who were depressed were not told they had a brain disease and they were not poisoned with harmful drugs.

A psychological, scientifically sound understanding of depression (and other commonly diagnosed mental disorders) originated in the early 1900s in psychology laboratories, where behaviorally oriented psychologists conducted studies on the process of learning. Behavioral psychologists are strict empiricists, and they reject theories that are not data-based. Their stance is very much in alignment with the scientific standards of Darwin, Mendel, and Dawkins. By the mid-1900s, their animal research had advanced sufficiently to enable studies of human learning, including of the behaviors that characterize mental disorder.

They found, as suggested by Dawkins, that the dysfunctional behaviors that characterize the mental disorders not only are learned behaviors, they are learned in the same way as normal, functional behaviors. With regard to depression, behavioral scientists found the chief causes to be adverse environments, dysfunctional responses to these negative conditions, and traumatic experiences of loss.

Several forms of learning were discovered. The simplest form of learning is Ivan Pavlov’s classical conditioning. Pavlov demonstrated a dog could be conditioned to salivate to a sound when it was paired with food—a physiological response not under voluntary control. A second form of learning, studied extensively by B. F Skinner, is called operant conditioning. This form of learning takes place because of the effects of a response. Favorable effects increase the likelihood a behavior will be repeated; unfavorable effects reduce that likelihood.

Behavioral research has revealed how the behaviors that characterize the mental disorders are learned according to these principles. An important finding is that learning can be determined by the short-term positive effects of behaviors even when the long-term effects are decidedly negative. Avoidance behaviors are governed in this way and have been verified to be the origin of the dysfunctional behaviors that define several mental disorders, including depression. Importantly, research results confirm that the deviant behaviors characterizing the mental disorders can be eliminated (cured) by applying these same principles to change this dysfunctional learning. This is the research that gave rise to the development of behavior therapy.

The first behavioral treatment, developed by Joseph Wolpe in the 1960s, was based on laboratory studies of fear conditioning and extinction which disclosed how fears are learned and how they can be unlearned. Wolpe was a psychiatrist, whose dissatisfaction with what he had learned in his psychiatric residency led him to apprentice in a psychology laboratory where psychologists were studying fear conditioning and extinction in cats. Based on that experience he developed a straightforward behavioral treatment designed to cure phobias. He stated that phobias are learned fears that can be eliminated by applying a simple procedure based on what he had learned in that lab. His treatment alarmed the psychoanalysts, who were the dominant mental health practitioners at that time. They regarded phobias as unconscious representations of hidden childhood traumas, and they were convinced by this theory that eliminating the phobia would precipitate a psychosis. The controversy continued in psychiatric and psychology journals for several years until Wolpe demonstrated his treatment, which he called systematic desensitization, worked well without any such disastrous effect. This treatment continues to be the treatment of choice for phobias.

Another treatment of a commonly diagnosed mental disorder, obsessive-compulsive disorder (OCD), also was devised on the basis of research in psychology laboratories on the process of learning. Edna Foa, a psychologist, devised a behavioral treatment for OCD, called exposure and response prevention, which also is based on eliminating avoidance behavior. It continues to be the best treatment for this disorder.

The best treatment for borderline personality disorder, a very serious mental disorder that previously was regarded as intractable, is Marsha Linehan’s dialectical behavior therapy, which she derived from psychological research.

Aaron Beck’s cognitive-behavioral treatment (CBT) for depression is based on how depression is caused psychologically by faulty assumptions, beliefs, and behaviors that adversely affect a person’s views of self, others, and the future, leading to depression. Beck, who was a psychiatrist, stated his treatment is educational, not medical. In great contrast to the negative outcome of antidepressant drugs, psychological treatment of depression is found to be significantly more effective than placebo, significantly more effective than drug treatment, and its effectiveness increases with time, probably because patients apply the lessons learned after treatment ends.

Behavioral treatments based on operant conditioning research are the best treatments we have for cocaine and amphetamine addiction.

Take note of the wide range of mental disorders treated successfully by psychological treatments derived empirically. If NIMH was doing its job, it would be developing a new DSM that follows the standards of diagnostic manuals for physical illnesses by specifying the psychological causation of each of the mental disorders and recommending the psychological treatment that causation dictates—neither of which is provided by psychiatry’s DSM.

Publication of the success of these psychological treatments predated psychiatry’s “medical revolution.” These treatments were found to be superior to psychoanalytic treatment when that was the treatment of choice, and they have since been found to be superior to drug treatments. This has not mattered to NIMH and psychiatry even if it has required making stuff up. Psychiatrists are determined to medicalize mental health care regardless of the research results which show that human behavior is largely a function of learning, not biology, and that behavior therapy, based on verified psychological principles, is effective whereas drug treatment is not.

Despite having had miniscule funding by NIMH in comparison with the funding of drug research, behavior therapy is the best treatment we have for depression and the other commonly diagnosed mental disorders. This is not to claim that behavior therapy is fully developed. More research is needed to advance how it is delivered in order to improve its effectiveness and efficiency. There is considerable reason to believe that if NIMH increases its funding of behavioral research the treatment will become even better.

The value and generality of behavioral psychology’s research findings has been amply substantiated by the ubiquitous application of this research for other purposes related to controlling human behavior. Google has used these principles in the design of its apps and Apple in its design of iPhones. Political consultants use them to get their candidates elected. The drug companies, who spend billions of dollars to prevent public understanding of the superiority of behavioral treatments over their drugs, are a prime example of how industries depend upon these principles to enhance their bottom line.

Sports psychologists and behavior therapists make use of these principles to help individuals, not powerfully funded commercial and political interests. Psychological principles are there for the taking. They exist in the same way gravity exists. The methodology is just as available to be used to benefit individuals as it is to serve commercial and political interests.

The scientific record is clear. The awful truth is that the claims made by psychiatric authorities are not to be trusted. Scientific research does not support how NIMH and psychiatry have influenced the public to believe that depression is of biological causation best treated medically. Psychological principles derived from research in psychology laboratories explain the causation of depression as psychological and verify the effectiveness of behavioral treatment for depression.

Rhetoric, not science, has determined the public’s erroneous beliefs of a biological basis for depression and the supposed value of antidepressant drugs. We are paying a heavy price for this misguidance.

Scientific data tell us that whereas physical illnesses have physical causation and should be treated medically, depression (and other commonly occurring mental disorders) is different. An abundance of scientific evidence tells us that depression is of psychological origin and that it should be treated psychologically by behavior therapy, not medically by antidepressant drugs.