The symptoms of depression are well characterized, but the subjective experiences of a depressed person are much harder to pin down.
According to the Diagnostic Statistical Manual, the primary symptoms of major depressive disorder include depressed mood and markedly diminished interest or pleasure in all or nearly all activities. These may be accompanied by changes in appetite and weight, trouble sleeping, fatigue, feelings of guilt or worthlessness, reduced ability to think or concentrate, and sometimes suicidal.
Beyond these clinical symptoms, depressed patients seem to experience the world differently from others. This is reflected in the terms used to describe a depressed state, such as feeling ‘blue’ – and there is indeed evidence that depression impairs sensory perception.
Depressed patients also report that their conscious experience has changed or been disrupted in such a way that they feel detached from the world and others. This aspect of depression is impossible to quantify. Psychiatrists have a hard time understanding this.
A world state
A new hypothesis seeks to explain the experiential aspect of depression.
In an article published in The British Journal for the Philosophy of Science, Cecily Whiteley of the London School of Economics describes depression as an altered state of consciousness. Whiteley suggests that thinking about depression in this way has important implications for a neuroscientific understanding of the condition and the emerging field of psychedelic psychiatry.
According to Whiteley, depression involves entering a distinct “global state” of consciousness, which involves a major change in the range and quality of a subject’s conscious experiences. It can be considered a dream-like and psychedelic-like state of mind, as well as disturbances of consciousness such as minimal consciousness and vegetative states.
Thus, depression consists of passing from one global state of consciousness to another. When an individual becomes depressed, he goes from a normal waking state to a depressed state.
This change involves a change in conscious experience and mental life, according to Whiteley. It alters the individual’s experience of their body, causing them to feel numb and lethargic and diminishing their sense of agency or control. This distorts their cognitive functions and self-narrative, reducing their ability to concentrate or think hopefully. It also changes their perception of time, making the future closed. Finally, it alters their relationships with others, making them feel distant and disconnected.
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According to Whiteley, considering depression as an overall state of consciousness could help understand why there is no satisfactory explanation for the mechanics of the disorder. Since we still know so little about how the brain generates a global state of consciousness, the neural mechanisms underlying depression are far beyond our grasp.
Can psychedelics beat depression?
Whiteley further argues that his proposed depressive state of consciousness helps explain the apparent successes of psychedelic psychiatry.
Although still in its infancy, research into the therapeutic benefits of psychedelic-assisted psychotherapy has already yielded positive results. In particular, psilocybin and ketamine have potential benefits for patients with depression and other mental disorders.
Psychedelics are well known for producing profound shifts in consciousness, and they can do this by triggering a transition from one global state of consciousness to another. In the case of depression, they might be able to shift patients from a depressed state to a psychedelic state, eventually restoring the normal state of wakefulness.
Although currently largely hypothetical, Whiteley’s thesis could have clinical applications. For example, perhaps neuroimaging techniques could distinguish between different global states of consciousness by measuring the complexity of long-range connections in the brain. If, as Whiteley claims, depression is one of these world states, this method could provide an objective diagnostic test.