Fahr disease is the old name for primary familial brain calcification (PFBC): bilateral calcium deposits in the basal ganglia and often other brain regions, without a metabolic or other secondary cause.
Doctors now prefer PFBC. Fahr syndrome usually means the same CT picture caused by something else (especially parathyroid disease). The two look similar on imaging; the workup is what separates them.
What happens in the brain
Calcium-phosphate (hydroxyapatite) builds up in:
- Globus pallidus, putamen, caudate
- Often thalamus, dentate nucleus of the cerebellum, and white matter
CT shows this best (bright, symmetric deposits). MRI is less sensitive for calcium. About a third of people with the genetic form never develop symptoms even though the scan is abnormal.
Symptoms (when they occur)
Typical onset is the 40s–60s, but it can be earlier. Patterns include:
- Movement: parkinsonism (slowness, stiffness, tremor, shuffling), dystonia, chorea, ataxia, slurred speech
- Thinking: cognitive slowing or dementia
- Mood/psychiatry: depression, anxiety, psychosis, personality change
- Other: headache, seizures (more often in children), gait trouble
Severity does not always match how much calcium is on the scan.
Causes
Primary (Fahr disease / PFBC) — genetic. Seven genes are established:
- Autosomal dominant: SLC20A2 (most common, ~50–60% of solved cases), PDGFB, PDGFRB, XPR1
- Autosomal recessive: MYORG, JAM2, NAA60
These genes affect phosphate transport or blood–brain barrier / pericyte function, so phosphate and calcium deposit in vessel walls. Radiologic penetrance is high; clinical penetrance is incomplete.
Secondary (Fahr syndrome) — treatable or other diseases that must be ruled out first:
- Hypoparathyroidism / pseudohypoparathyroidism (most important)
- Other calcium–phosphate disorders, vitamin D problems
- Infections, toxins, mitochondrial disease, some syndromes
How it is diagnosed
- CT showing bilateral basal ganglia calcification
- Blood tests: calcium, phosphate, PTH, vitamin D (to exclude endocrine causes)
- If secondary causes are negative: genetic testing of PFBC genes
- Family history helps but is not required (de novo and recessive cases exist)
Physiologic “aging” specks in the pallidum in older adults are not Fahr disease.
Treatment
There is no drug that dissolves the calcium or stops the genetic process.
- Treat the cause if it is Fahr syndrome (e.g., correct hypoparathyroidism with calcium and vitamin D).
- For PFBC, care is symptomatic: levodopa for some parkinsonism (response is mixed), botulinum toxin for dystonia, antiseizure drugs, antidepressants/antipsychotics as needed, rehab and speech therapy.
- Genetic counseling is useful for families.
This is not medical advice for a specific person. If a scan showed basal ganglia calcification, a neurologist should sort primary vs secondary disease and decide on labs and genetics.
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