Tauopathy belongs to a class of neurodegenerative diseases associated with the pathological aggregation of tau protein in neurofibrillary or gliofibrillary tangles in the human brain. Tangles are formed by hyperphosphorylation of a microtubule-associated protein known as tau, causing it to aggregate in an insoluble form. (These aggregations of hyperphosphorylated tau protein are also referred to as paired helical filaments). The precise mechanism of tangle formation is not completely understood, and it is still controversial as to whether tangles are a primary causative factor in the disease or play a more peripheral role. Primary tauopathies, i.e., conditions in which neurofibrillary tangles (NFT) are predominantly observed, include:

- Primary age-related tauopathy (PART)/Neurofibrillary tangle-predominant senile dementia, with NFTs similar to AD, but without plaques.

- Chronic traumatic encephalopathy, including dementia pugilistica

- Progressive supranuclear palsy

- Corticobasal degeneration

- Frontotemporal dementia and parkinsonism linked to chromosome 17

- Lytico-Bodig disease (Parkinson-dementia complex of Guam)

- Ganglioglioma and gangliocytoma

- Meningioangiomatosis

- Postencephalitic parkinsonism

- Subacute sclerosing panencephalitis

- As well as lead encephalopathy, tuberous sclerosis, Hallervorden-Spatz disease, and lipofuscinosis

Neurofibrillary tangles were first described by Alois Alzheimer in one of his patients suffering from Alzheimer's disease (AD), which is considered a secondary tauopathy. AD is also classified as an amyloidosis because of the presence of senile plaques.

The degree of NFT involvement in AD is defined by Braak stages. Braak stages I and II are used when NFT involvement is confined mainly to the transentorhinal region of the brain, stages III and IV when there's also involvement of limbic regions such as the hippocampus, and V and VI when there's extensive neocortical involvement. This should not be confused with the degree of senile plaque involvement, which progresses differently.

In both Pick's disease and corticobasal degeneration, tau proteins are deposited as inclusion bodies within swollen or "ballooned" neurons.

Argyrophilic grain disease (AGD), another type of dementia, is marked by an abundance of argyrophilic grains and coiled bodies upon microscopic examination of brain tissue. Some consider it to be a type of Alzheimer's disease. It may co-exist with other tauopathies such as progressive supranuclear palsy and corticobasal degeneration, and also Pick's disease.

Huntington's disease (HD): a neurodegenerative disease caused by a CAG tripled expansion in the Huntington gene is the most recently described tauopathy (Fernandez-Nogales et al. Nat Med 2014). JJ Lucas and co-workers demonstrate that, in brains with HD, tau levels are increased and the 4R/3R balance is altered. In addition, the Lucas study shows intranuclear insoluble deposits of tau; these "Lucas' rods" were also found in brains with Alzheimer's disease.

Tauopathies are often overlapped with synucleinopathies, possibly due to interaction between the synuclein and tau proteins.

The non-Alzheimer's tauopathies are sometimes grouped together as "Pick's complex" due to their association with frontotemporal dementia, or frontotemporal lobar degeneration.

The aim in cerebral amyloid angiopathy is to treat the symptoms, as there is no current cure. Physical and/or speech therapy may be helpful in the management of this condition.

The drug tafamidis has completed a phase II/III 18-month-long placebo controlled clinical trial

and these results in combination with an 18-month follow-on study demonstrated that Tafamidis or Vyndaqel slowed progression of FAP, particularly when administered to patients early in the course of FAP. This drug is now approved by the European Medicines Agency.

The US Food and Drug Administration's Peripheral and Central Nervous System Drugs Advisory Committee rejected the drug in June 2012, in a 13-4 vote. The committee stated that there was not enough evidence supporting efficacy of the drug, and requested additional clinical trials.

Drug and therapeutic treatments exist in order to battle this disease; however many have proven ineffective.

Chlorambucil is a chemotherapy drug normally used to treat leukemia as it is often used as an immunosuppressant drug, and prednisone is a steroid that has also been found to be particularly effective as an immunosuppressant. This combination of drugs has minimal to no benefits in most patients, but a small number do see small improvements such as decreased tremors. This combination has not been very effective in more severe cases, though, and is not considered a long term therapy.

In the absence of a liver transplant, FAP is invariably fatal, usually within a decade. The disadvantage of liver transplantation is that approximately 10% of the subjects die from the procedure or complications resulting from the procedure, which is a form of gene therapy wherein the liver expressing wild type and mutant TTR is replaced by a liver only expressing wild type TTR. Moreover, transplanted patients must take immune suppressants (drugs) for the remainder of their life, which can lead to additional complications. In late 2011, the European Medicines Agency approved the transthyretin kinetic stabilizer Tafamidis or Vyndaqel discovered by Jeffery W. Kelly and developed by FoldRx pharmaceuticals (acquired by Pfizer in 2010) for the treatment of FAP based on clinical trial data. Tafamidis (20 mg once daily) slowed the progression of FAP over a 36-month period and importantly reversed the weight loss and muscle wasting associated with disease progression.

Liver transplantation has proven to be effective for ATTR familial amyloidosis due to Val30Met mutation.

Alternatively, a European Medicines Agency approved drug Tafamidis or Vyndaqel now exists which stabilizes transthyretin tetramers comprising wild type and different mutant subunits against amyloidogenesis halting the progression of peripheral neuropathy and autonomic nervous system dysfunction.

Currently there are two ongoing clinical trials undergoing recruitment in the United States and worldwide to evaluate investigational medicines that could possibly treat TTR.

RS3PE responds excellently to low dose corticosteroids, with sustained and often complete remission. Non-steroidal anti-inflammatory drugs (NSAIDs) have also been used. Hydroxychloroquine has proven effective in some cases.

Cerebral amyloid angiopathy (CAA), also known as congophilic angiopathy, is a form of angiopathy in which amyloid deposits form in the walls of the blood vessels of the central nervous system. The term "congophilic" is used because the presence of the abnormal aggregations of amyloid can be demonstrated by microscopic examination of brain tissue after application of a special stain called Congo red. The amyloid material is only found in the brain and as such the disease is not related to other forms of amyloidosis.

No drug has been shown to be able to arrest or slow down the process of this condition. There is promise that two drugs, tafamidis and diflunisal, may improve the outlook, since they were demonstrated in randomized clinical trials to benefit patient affected by the related condition FAP-1 otherwise known as transthyretin-related hereditary amyloidosis. Permanent pacing can be employed in cases of symptomatic slow heart rate (bradycardia). Heart failure medications can be used to treat symptoms of difficulty breathing and congestion.

Treatment includes supportive care with analgesics and anti-inflammatory agents. Exercise should be limited as it increases pain and extends the area of infarction. Symptoms usually resolve in weeks to months, but fifty percent of sufferers will experience relapse in either leg.

Treatment depends on the type of amyloidosis that is present. Treatment with high dose melphalan, a chemotherapy agent, followed by stem cell transplantation has showed promise in early studies and is recommended for stage I and II AL amyloidosis. However, only 20–25% of people are eligible for stem cell transplant. Chemotherapy and steroids, with melphalan plus dexamethasone, is mainstay treatment in AL people not eligible for transplant.

In AA, symptoms may improve if the underlying condition is treated; eprodisate has been shown to slow renal impairment by inhibiting polymerization of amyloid fibrils.

In ATTR, liver transplant is a curative therapy because mutated transthyretin which forms amyloids is produced in the liver.

People affected by amyloidosis are supported by multiple organizations, including the Amyloidosis Foundation, Amyloidosis Support Groups Inc., and Amyloidosis Australia, Inc.

The most effective treatment is autologous bone marrow transplants with stem cell rescues. However many patients are too weak to tolerate this approach.

Other treatments can involve application of chemotherapy similar to that used in multiple myeloma. A combination of melphalan and dexamethasone has been found effective in those who are ineligible for stem cell transplantation, and a combination of bortezomib and dexamethasone is now in widespread clinical use.

In medicine, proteopathy (Proteo- ["pref". protein]; -pathy ["suff". disease]; proteopathies "pl".; proteopathic "adj".) refers to a class of diseases in which certain proteins become structurally abnormal, and thereby disrupt the function of cells, tissues and organs of the body. Often the proteins fail to fold into their normal configuration; in this misfolded state, the proteins can become toxic in some way (a gain of toxic function) or they can lose their normal function. The proteopathies (also known as proteinopathies, protein conformational disorders, or protein misfolding diseases) include such diseases as Creutzfeldt–Jakob disease and other prion diseases, Alzheimer's disease, Parkinson's disease, amyloidosis, and a wide range of other disorders (see List of Proteopathies).

The concept of proteopathy can trace its origins to the mid-19th century, when, in 1854, Rudolf Virchow coined the term amyloid ("starch-like") to describe a substance in cerebral corpora amylacea that exhibited a chemical reaction resembling that of cellulose. In 1859, Friedreich and Kekulé demonstrated that, rather than consisting of cellulose, "amyloid" actually is rich in protein. Subsequent research has shown that many different proteins can form amyloid, and that all amyloids have in common birefringence in cross-polarized light after staining with the dye Congo Red, as well as a fibrillar ultrastructure when viewed with an electron microscope. However, some proteinaceous lesions lack birefringence and contain few or no classical amyloid fibrils, such as the diffuse deposits of Aβ protein in the brains of Alzheimer patients. Furthermore, evidence has emerged that small, non-fibrillar protein aggregates known as oligomers are toxic to the cells of an affected organ, and that amyloidogenic proteins in their fibrillar form may be relatively benign.

Since interleukin 1β plays a central role in the pathogenesis of the disease, therapy typically targets this cytokine in the form of monoclonal antibodies (such as canakinumab), binding proteins/traps (such as rilonacept), or interleukin 1 receptor antagonists (such as anakinra). These therapies are generally effective in alleviating symptoms and substantially reducing levels of inflammatory indices. Case reports suggest that thalidomide and the anti-IL-6 receptor antibody tocilizumab may also be effective.

Attacks are self-limiting, and require analgesia and NSAIDs (such as diclofenac). Colchicine, a drug otherwise mainly used in gout, decreases attack frequency in FMF patients. The exact way in which colchicine suppresses attacks is unclear. While this agent is not without side effects (such as abdominal pain and muscle pains), it may markedly improve quality of life in patients. The dosage is typically 1–2 mg a day. Development of amyloidosis is delayed with colchicine treatment. Interferon is being studied as a therapeutic modality. Some advise discontinuation of colchicine before and during pregnancy, but the data are inconsistent, and others feel it is safe to take colchicine during pregnancy.

Approximately 5–10% of FMF cases are resistant to colchicine therapy alone. In these cases, adding anakinra to the daily colchicine regimen has been successful.

Most people, including those treated with ASCT, will relapse after initial treatment. Maintenance therapy using a prolonged course of low toxicity medications is often used to prevent relapse. A 2017 meta-analysis showed that post ASCT maintenance therapy with lenalidomide improved progression free survival and overall survival in people at standard risk. A 2012 clinical trial showed that people with intermediate and high risk disease benefit from a bortezomib based maintenance regimen.

Treatment is based on the underlying cause, if any. Where the likely underlying condition is known, treatment of this condition is indicated treated to reduce progression of the disease and symptoms. For cases without those conditions, there is only symptomatic treatment.

Initial treatment of multiple myeloma depends on the patient’s age and comorbidities.

The preferred treatment for those under the age of 65 is high-dose chemotherapy, commonly with bortezomib based regimens, and lenalidomide–dexamethasone. This is followed by autologous hematopoietic stem-cell transplantation (ASCT) - the transplantation of a patient’s own stem cells. It is not curative, but does prolong overall survival and complete remission. Allogeneic stem cell transplantation, the transplantation of a healthy person’s stem cells into the affected patient, has the potential for a cure, but is used in a very small percentage of patients (and in the relapsed setting, not as part of initial treatment). Furthermore, there is a 5–10% treatment-associated mortality rate associated with allogeneic stem cell transplant.

People over age 65 and people with significant concurrent illness often cannot tolerate stem cell transplantation. For these patients, the standard of care has been chemotherapy with melphalan and prednisone. Recent studies among this population suggest improved outcomes with new chemotherapy regimens, e.g., with bortezomib. Treatment with bortezomib, melphalan, and prednisone had an estimated overall survival of 83% at 30 months, lenalidomide plus low-dose dexamethasone an 82% survival at 2 years and melphalan, prednisone and lenalidomide had a 90% survival at 2 years. Head-to-head studies comparing these regimens have not been performed .

A 2009 review noted "Deep venous thrombosis and pulmonary embolism are the major side effects of

thalidomide and lenalidomide. Lenalidomide causes more myelosuppression, and thalidomide causes more sedation. Chemotherapy-induced peripheral neuropathy and thrombocytopenia are major side effects of bortezomib."

Treatment of related hyperviscosity syndrome may be required to prevent neurologic symptoms or kidney failure.

The familial amyloid neuropathies (or familial amyloidotic neuropathies, neuropathic heredofamilial amyloidosis, familial amyloid polyneuropathy) are a rare group of autosomal dominant diseases wherein the autonomic nervous system and/or other nerves are compromised by protein aggregation and/or amyloid fibril formation.

There is no standard treatment for LCDD. High-dose melphalan in conjunction with autologous stem cell transplantation has been used in some patients. A regimen of bortezomib and dexamethasone has also been examined.

The protein electrophoresis test should be repeated annually, and if there is any concern for a rise in the level of monoclonal protein, then prompt referral to a hematologist is required. The hematologist, when first evaluating a case of MGUS, will usually perform a skeletal survey (X-rays of the proximal skeleton), check the blood for hypercalcemia and deterioration in renal function, check the urine for Bence Jones protein and perform a bone marrow biopsy. If none of these tests are abnormal, a patient with MGUS is followed up once every 6 months to a year with a blood test (serum protein electrophoresis). Although patients with MGUS have sometimes been reported to suffer from Small Fiber Neuropathy in monoclonal gammopathy of undetermined significance:a debilitating condition which causes bizarre sensory problems to painful sensory problems. peripheral neuropathy, no treatment is indicated.

Some proteins can be induced to form abnormal assemblies by exposure to the same (or similar) protein that has folded into a disease-causing conformation, a process called 'seeding' or 'permissive templating'. In this way, the disease state can be brought about in a susceptible host by the introduction of diseased tissue extract from an afflicted donor. The best known form of such inducible proteopathy is prion disease, which can be transmitted by exposure of a host organism to purified prion protein in a disease-causing conformation. There is now evidence that other proteopathies can be induced by a similar mechanism, including Aβ amyloidosis, amyloid A (AA) amyloidosis, and apolipoprotein AII amyloidosis, tauopathy, synucleinopathy, and the aggregation of superoxide dismutase-1 (SOD1), polyglutamine, and TAR DNA-binding protein-43 (TDP-43).

In all of these instances, an aberrant form of the protein itself appears to be the pathogenic agent. In some cases, the deposition of one type of protein can be experimentally induced by aggregated assemblies of other proteins that are rich in β-sheet structure, possibly because of structural complementarity of the protein molecules. For example, AA amyloidosis can be stimulated in mice by such diverse macromolecules as silk, the yeast amyloid Sup35, and curli fibrils from the bacterium "Escherichia coli". In addition, apolipoprotein AII amyloid can be induced in mice by a variety of β-sheet rich amyloid fibrils, and cerebral tauopathy can be induced by brain extracts that are rich in aggregated Aβ. There is also experimental evidence for cross-seeding between prion protein and Aβ. In general, such heterologous seeding is less efficient than is seeding by a corrupted form of the same protein.

Median survival for patients diagnosed with AL amyloidosis was 13 months in the early 1990s, but had improved to c. 40 months a decade later.

There has too little experience on the treatment of LECT2 amyloidosis to establish recommendations other than offering methods to support kidney function and dialysis. Nonetheless, it is important to accurately diagnose ALECT2-based amyloid disease in order to avoid treatment for other forms of amyloidosis.