The Upward Spiral

Alex Korb, a neuroscientist specializing in mood disorders, argues that depression is not caused by a single broken brain component but by the tuning and interaction of neural circuits, and that small, science-backed life changes can alter brain activity and chemistry to reverse its course. The book is divided into two parts: the first explains how the brain gets stuck in a downward spiral of depression, and the second offers a toolbox of strategies for creating an upward spiral.

Korb opens with three studies illustrating the book's central premise. A woman's worry and danger circuits calmed when her husband held her hand during electric shocks. A young man's serotonin and emotional control circuits activated after 15 minutes of stationary biking. Hospital patients recovering from spinal surgery in sunnier rooms needed less pain medication. These findings point to a core insight: Positive life changes cause positive neural changes, which lead to further positive life changes.

In Part 1, Korb maps the brain regions and chemical systems involved in depression. He identifies three main systems: the prefrontal cortex (responsible for planning, decision-making, and overriding impulses), the limbic system (a collection of structures governing emotions, fear, memory, and stress), and the striatum (which controls habits and impulses). Depression arises when communication among these regions becomes dysfunctional. Korb shares his own experience of depression during his senior year of college, when anxiety, a breakup, and loss of appetite left him feeling heavy and slow. He unknowingly staved off a deeper spiral through sports, sunlight, and living with close friends, all of which altered his brain chemistry.

He details the key neurotransmitters, the chemical messengers neurons use to communicate. Serotonin affects willpower and mood; norepinephrine influences focus and stress; dopamine drives motivation and habits; oxytocin promotes trust and connection; GABA, linked to relaxation and reduced anxiety, calms the nervous system; and endocannabinoids, involved in appetite and well-being, contribute alongside melatonin and endorphins. Within the limbic system, the amygdala generates fear responses, the hippocampus forms memories and is vulnerable to stress-related damage, the hypothalamus triggers the body's fight-or-flight stress response, and the anterior cingulate directs attention toward mistakes and pain. The insula processes bodily sensations and amplifies pain in depression. The striatum's dorsal part controls routines while the nucleus accumbens drives pleasure-seeking impulses; reduced dopamine activity in both contributes to the fatigue and loss of enjoyment characteristic of depression.

Korb examines how worry and anxiety trap the brain in a downward spiral. Worry is thought-based, driven by the prefrontal cortex cycling through negative future scenarios, while anxiety is sensation-based, driven by the limbic system's fear circuitry responding to potential rather than actual danger. He presents the ABCs of anxiety: Alarm (the brain notices something wrong), Belief (a subconscious evaluation of the threat), and Coping (the habitual action that follows). Simply naming an emotion activates the prefrontal cortex and reduces amygdala reactivity, and mindfulness can cut off worry and anxiety at their source by redirecting attention to the present moment.

The brain's negative bias compounds the problem. The brain pays more attention to negative events, and depression amplifies this tendency. Mood-congruent bias means a bad mood causes a person to notice more negativity, which worsens mood further. Depression also distorts memory: the stressed amygdala prompts the hippocampus to store negative memories while happy memories become harder to recall. Rumination, the repetitive focus on negative emotions, is driven by the default mode network, a set of brain regions active during mind-wandering that becomes wired for excessive negative self-focus in depression.

Korb closes Part 1 by examining bad habits. He introduces his friend Billi, a neuroscientist who grew up in poverty with abusive parents and faced racism and homophobia. Billi used food to cope with accumulated stress, eventually weighing 700 pounds. Billi's story illustrates how stress-driven habits become ingrained in the dorsal striatum through repetition and persist even without pleasure. Stress shifts power from the deliberate prefrontal cortex to the automatic striatum, making old habits harder to override and new behaviors harder to initiate.

Part 2 presents the toolbox for creating an upward spiral, beginning with exercise. Exercise increases brain-derived neurotrophic factor (BDNF), a protein that promotes neuron growth; boosts serotonin and norepinephrine; positively affects the dopamine system; releases endorphins and endocannabinoids; reduces stress hormones; and improves sleep. Korb shares his own recovery from a sedentary downward spiral, starting with short walks and eventually training for a marathon.

He argues that making decisions and setting goals engage the prefrontal cortex in ways that reduce worry, override bad habits, and increase enjoyment. Actively choosing a goal makes achieving it more rewarding, and even perceived control over a situation lowers stress. Setting specific, meaningful goals aligned with personal values increases dopamine with each step toward achievement.

Korb explains that poor sleep both causes and worsens depression. The brain cycles through stages in 90-minute loops, and depression is associated with increased rapid eye movement (REM) sleep and less restorative slow-wave sleep, in which the brain's electrical activity dramatically slows for deep restoration. Circadian rhythms, the body's daily biological cycles governed by the hypothalamus and synchronized to daylight, control melatonin release and affect mood. He recommends consistent bedtimes, bright morning light, and avoiding screens before bed, and introduces cognitive behavioral therapy for insomnia (CBT-I) as a targeted method for improving sleep quality.

The chapter on habits explains that new habits require repetition to wire into the dorsal striatum. Reducing stress makes it easier to resist old routines, and self-compassion rather than self-criticism sustains motivation. Korb lists four ways to boost serotonin for better impulse control: sunlight, massage, exercise, and remembering happy memories. Improving eating habits also matters, as gut bacteria affect serotonin and GABA signaling.

Korb explains biofeedback as the brain changing its activity based on what the body is doing. Smiling increases positive feelings, confident posture enhances decisiveness, and slow breathing activates the vagus nerve, which carries body-state information to the brain, engaging the parasympathetic nervous system, the body's rest-and-digest system, to calm the stress response. Yoga combines many of these elements and stimulates GABA, the same system targeted by antianxiety medications.

He presents gratitude as a potent antidote to the brain's negative bias. Gratitude activates dopamine circuits, boosts serotonin in the anterior cingulate, and improves sleep. Korb broadens the concept to include optimism, humor, compassion, and awe, and cautions against confusing gratitude with social comparison, which activates different circuits. The act of searching for things to be grateful for, not necessarily finding them, is what activates the beneficial circuitry.

The chapter on social support explains that interacting with others changes brain chemistry through oxytocin, a neurohormone that promotes trust and connection while reducing anxiety and pain. Even passive proximity to others helps. Holding hands reduces pain circuit activation, talking with friends increases oxytocin and reduces stress hormones, and volunteering improves depression symptoms. Korb warns that social media tends to worsen well-being when used for passive scrolling rather than meaningful connection.

The final chapter covers professional help. Psychotherapy changes the brain differently than medication: Therapy normalizes limbic reactivity and increases serotonin receptors in the prefrontal cortex, while antidepressant medications like selective serotonin reuptake inhibitors (SSRIs) block serotonin transporters and reduce limbic reactivity. Combining the two nearly doubles the chances of improvement. Korb describes newer treatments including ketamine, which targets glutamate receptors for rapid effects, and psilocybin, the psychoactive compound in certain mushrooms, which disrupts communication between the limbic system and default mode network. He also surveys brain stimulation techniques such as transcranial magnetic stimulation and electroconvulsive therapy.

Korb concludes by emphasizing that all brain circuits influence each other, so solutions are not always straightforward: Gratitude improves sleep, which reduces pain, which improves mood, which reduces anxiety, which improves focus and planning. He stresses two foundational insights: Depression is not a person's fault but a matter of brain biology, and this biology is malleable and can be changed through small, intentional steps.