When the body is the cause.
Panic can fire from the chemistry of the blood, below the brain’s fear centre. Standing can cut brain blood flow before the racing heart arrives. Anxiety is real. The body deserves a look before the label is fixed.
Some of what gets treated as anxiety is the supply running short.
Lower the brain’s blood supply and the first thing you notice can be hard to tell from a panic attack or a stretch of depression: a pounding heart, dread, dizziness, a mind that loses the thread. So conditions like long COVID and dysautonomia, the slow drains that tip a borderline case over the line, often meet a psychiatric label before anything else. The feeling is real. But when its source is the circulation, calming the feeling leaves the source untouched.
POTS is the clearest example, only because it has been counted. Most people with it are told it is anxiety or something psychological before anyone finds the autonomic cause.1 Yet formally assessed, people with POTS turn out to have no more anxiety disorder than anyone else: orthostatic stress just makes a person look wired.3
And it is not only POTS. Paroxysmal SVT, a heart-rhythm disorder a single procedure can cure, is mistaken for panic or anxiety in more than half of patients, for a median of about three years before the rhythm is found, and once it is fixed almost none still meet the criteria for panic.4 The label had fixed on the symptom while the cause went unfound.
Shown identical filmed heart-attack symptoms, doctors named a mental-health cause about twice as often when the patient was a woman, and adding a mention of stress tipped the reading further.5 It carries into real emergencies: among young adults having an actual heart attack, 53% of women against 37% of men were told their symptoms were not coming from the heart.6 POTS and dysautonomia, diagnosed overwhelmingly in women, sit squarely in that blind spot.
A psychiatric label pinned on before the body is checked closes the search too early. People told their organic illness is psychological carry more anxiety and depression, less trust in doctors, and more avoidance of care, long after the right diagnosis arrives.7 The label is usually meant to reassure. The fix is to check the body first.
There is a real boundary here, worth stating plainly. When a specialist makes a positive anxiety or functional diagnosis after a full workup, it is later overturned to a missed physical disease only about one time in twenty-five, and the errors run both ways.8 The failure this section is about is the earlier one: the label reached for before the body has been looked at, where most labelling happens.
This is not a handful of edge cases. About one adult in five carries an anxiety diagnosis in a given year, most of it handled in primary care rather than psychiatry,9 and the blood-flow mechanism on this page is one real contributor, documented condition by condition. What no one has measured is how much of that pool is circulation read as panic. After an infection almost everyone has now had, even a single-digit fraction of so large a group runs to hundreds of thousands of people. The absence of study is not evidence the effect is small; it is why the number is still unknown.
What to ask for, and the one rule before exercise
If it gets worse on standing, ask for an objective stand test. Orthostatic intolerance has a clear signature: a sustained rise of about 30 beats per minute within ten minutes of standing, or on a tilt table, with no fall in blood pressure. That number separates an autonomic cause from anxiety, and it cuts both ways, since not everyone who feels dizzy has POTS. Autonomic trouble is common after COVID, so it is worth measuring rather than assuming.10
On medication, the one to question is the reflex sedative. Benzodiazepines carry dependence, blunting and, mostly from older-adult data rather than POTS or long COVID, raised fall risk, and guidelines lean away from them, partly because they quiet the feeling while the cause stays unlooked-for.11 This is not a case against the rest. A low-dose beta-blocker can be a mechanism-matched treatment for the racing heart, and antidepressants are real treatment for real depression. Do not start, stop or change any of it on your own, and benzodiazepines in particular need a slow, supervised taper.
Before “just move more,” one rule that is not optional. Where the problem is deconditioning, a careful, recumbent-first rebuild helps. But screen first for post-exertional malaise, the delayed crash that lands a day or two after exertion. Where that crash is present, as in ME/CFS and some long COVID, push-through or fixed-increment exercise can do lasting harm; pacing within your limits is the safer path.12 The deciding factor is that crash, not the label on the chart.
Mind and mood.
Real anxiety and depression exist and respond to treatment. So does the version where the body is the cause. Each entry carries its own verdict and evidence.
Anxiety growing evidence
For the panic and the standing kind, anxiety’s link to blood flow is easy to measure. Over-breathing in a panic attack drops blood CO2 and clamps the brain’s arteries; flow in the main cerebral artery has been clocked falling a fifth during a real attack, and the drop comes before the racing heart, not after.13 The same loop runs in orthostatic intolerance: standing cuts brain blood flow twice as much as normal, the shortfall arriving seconds ahead of the adrenaline surge.14 That is why most of these patients end up labelled with an anxiety disorder before the cause is found.1 Much of what gets called anxiety here is the brain reacting, correctly, to being briefly starved of blood.
That the body can raise the alarm on its own is not a metaphor. Three people whose amygdala had been destroyed, who feel no fear of snakes or haunted houses, still had full panic attacks the moment they breathed in air rich in CO2: the alarm can fire from the chemistry of the blood, below the part of the brain that handles fear.15
There is also a resting version. Generalised anxiety does not change whole-brain flow as a single number, but region by region it is consistent: the brain’s threat circuitry, the amygdala and anterior insula, runs over-perfused while the prefrontal cortex that should regulate it is under-engaged. The largest test scanned 875 people at rest and found trait anxiety tracked elevated amygdala and insula flow.16 And the arrow runs both ways: chronic low brain blood flow can itself generate anxiety.17
Depression growing evidence
Researchers now read depression as partly a disorder of vessels and inflammation. In older adults, small-vessel damage in the brain predicts new depression, and depressed adults show dysfunction of the vessel lining and raised inflammation in body and brain.1819 Blood flow is altered too, region-specific, some areas higher and some lower.20
Schizophrenia and psychosis mixed, region-specific
Schizophrenia does not lower brain blood flow evenly. The frontal and limbic cortex tends to run underperfused, the classic hypofrontality that tracks negative symptoms like flat affect, while deeper structures such as the striatum tend to run overperfused, tracking positive symptoms such as hallucinations and delusions.21 There is also molecular evidence of a leakier blood-brain barrier: the tight-junction protein claudin-5 is patchy or broken in most postmortem cases, and the 22q11 deletion that removes one copy of its gene carries a roughly 30-fold rise in risk. The specific gene-variant link, though, is weak.22 Microglial neuroinflammation is plausible but the in-vivo imaging is mixed, so these flow and barrier changes are one strand of a complex disorder, tied to metabolism, symptom state and medication, not a single upstream cause.23
PTSD a circuit imbalance
PTSD perfusion is region-specific and reactivity-driven rather than a whole-brain drop. When a trauma cue hits, the amygdala over-responds while the medial prefrontal cortex that should calm it goes quiet, and the size of that imbalance tracks how severe the symptoms are.24 The prefrontal regulatory failure sets PTSD apart from the other anxiety disorders, hypoactivation of the anterior cingulate and ventromedial prefrontal cortex, rather than a louder alarm.25 At rest, perfusion is mostly preserved and in places even locally elevated rather than uniformly low.26 The robust evidence is about reactivity and regional balance, much of it from male combat-veteran samples, so the perfusion changes follow from an over-reactive threat circuit, not a primary vascular cause.
Bipolar disorder secondary, mood-linked
Bipolar disorder does change brain blood flow, but mostly during mood episodes: imaging shows altered perfusion in cingulate, frontal and temporal regions during depression and mania that is inconsistent between episodes, so flow tracks mood state rather than marking a fixed injury.27 The sturdier vascular link is what comes with bipolar disorder: small-vessel white-matter lesions are nearly twice as common, and cardiovascular disease strikes about a decade early, beyond what lifestyle and medication explain.2829 Even vessel-lining function flips with mood, worsening in depression, so the vascular link here is real but secondary and mood-modulated, not the steady, causal small-vessel decline you see in the dementias.30
If your symptoms are worst on standing, see when standing is the problem. For what moves any of this, see what helps.
Keep your brain better supplied.
Most research on cerebral blood flow never reaches the people it could help. We read it and send only what changes what you can do: a new way to raise your own blood flow, or a finding that moves the advice on this page.