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Name: Pioglitazone
Synonyms: AD4833, Actos®, Glustin™, Piozone®
Chemical Name: 2,4-Thiazolidinedione
Therapy Type: Small Molecule (timeline)
Target Type: Inflammation (timeline), Other (timeline)
Condition(s): Mild Cognitive Impairment
U.S. FDA Status: Mild Cognitive Impairment (Phase 3)
Company: Takeda Pharmaceutical Company, Zinfandel Pharmaceuticals Inc.
Approved for: Type 2 diabetes mellitus


Pioglitazone is an insulin sensitizer of the thiazolidinedione class of peroxisome-proliferator activated receptor γ (PPARγ) agonists. Takeda developed pioglitazone as a once-daily treatment of type 2 diabetes. The FDA approved it in 1999 as an adjunct to diet and exercise for the control of blood sugar in adults with this disease. Since then pioglitazone has come to be prescribed worldwide, but was withdrawn from the market in Germany and France because of concerns that it might increase the risk of bladder cancer. The issue remains under review in the United States, though in its update issued in August 2013, the FDA did not conclude that pioglitazone increased the risk of bladder cancer. Generic tablet versions became available starting in 2012.

In recent years, PPARγ has come to be a target of interest for Alzheimer's drug development, both because of a general overlap of metabolic disease and Alzheimer's disease risk factors and because cell-based and animal studies have implicated PPARγ, in particular, to play a role in neuroinflammatory processes in Alzheimer's and other neurodegenerative conditions. For example, PPARγ activation has been shown to modulate the microglial response to amyloid deposition in such a way that it increases Aβ phagocytosis and decreases cytokine release (Dec 2012 news storyYamanaka et al., 2012Mandrekar-Colucci et al., 2012).


From 2002 to 2005, a Phase 2 study sponsored by the National Institute on Aging evaluated the safety and tolerability of pioglitazone in patients with AD and gathered pilot data on whether this drug might affect measures of cognition, daily function, and behavior. Twenty-nine patients with mild to moderate AD but without diabetes took up to 45 mg per day of pioglitazone or placebo for 18 months. Consistent with the known side effects of pioglitazone, about a fourth of participants developed peripheral edema; other than that they tolerated the drug well. No indications for a clinical benefit arose from this trial (see Geldmacher et al., 2011Sep 2010 news story).

A Japanese open-label study of 42 patients who had both mild Alzheimer's and diabetes suggested a benefit for both diseases after six months of treatment with 15 to 30 mg/day of pioglitazone, as did a previous pilot study in patients who had mild AD or mild cognitive impairment and diabetes (Sato et al., 2011; Hanyu et al., 2009).

In 2012, Takeda conducted a Phase I trial in the United States to evaluate the effects of two weeks of pioglitazone treatment on blood flow in brain areas important for cognition in 61 healthy older participants (NCT01456117). Results are unpublished.

In 2013-2015, Takeda and Zinfandel Pharmaceuticals conducted "TOMMORROW," a Phase 3 trial that enrolled 3,494 cognitively normal participants in the United States, Australia, Europe, and the U.K. This study was unusual in that it had two separate goals. One was to evaluate how accurately a diagnostic algorithm based on the genes ApoE and TOMM40, developed by Zinfandel, predicts a person's risk of developing mild cognitive impairment due to AD (MCI-AD) within five years. The other was to evaluate pioglitazone's ability to delay this diagnosis in people deemed high-risk by the diagnostic assay. The assay is being co-developed as a companion diagnostic for preventive treatment. Participants at high risk of developing MCI-AD according to the diagnostic algorithm were randomized to pioglitazone or placebo; participants at low risk received placebo. The primary endpoint for the diagnostic assay was the time to diagnosis for placebo-treated participants in the low-risk group compared with the high-risk group; the primary endpoint for pioglitazone was the time to diagnosis for pioglitazone-treated versus placebo-treated participants in the high-risk group. This trial used 0.8 mg pioglitazone per day, a lower dose than is used to treat diabetes (Moon et al., 2011). Approximately 300 high-risk participants will enter an amyloid-related imaging abnormalities (ARIA) substudy. Each participant was to take a tablet—pioglitazone or placebo—once daily for five years, visit his or her study clinic 14 times, and take a telephone call three months after each visit for a follow-up assessment (Aug 2013 conference story). Approximately 300 high-risk participants entered an ARIA substudy at the request of the FDA. This was later changed to volumetric MRI, on the understanding that low-dose pioglitazone was unlikely to affect brain amyloid.

In early 2018, TOMMORROW was terminated after failing a futility analysis (Jan 2018 news). According to published trial results, pioglitazone did not delay the onset of MCI, after a mean treatment time of about two years. The diagnostic algorithm produced a three-times enrichment of events in the high-risk placebo group compared to the low-risk placebo group, but did not reach a prespecified significance threshold (Burns et al., 2021). The treatment did not alter the rate of change of brain volumes on MRI.

For trials of pioglitazone in Alzheimer's disease, see

In addition, pioglitazone was evaluated in a Phase 1 study in patients with multiple sclerosis, but development for this indication stopped.

Clinical Trial Timeline

  • Phase 2
  • Phase 3
  • Study completed / Planned end date
  • Planned end date unavailable
  • Study aborted
Sponsor Clinical Trial 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034
Takeda Pharmaceutical Company NCT00982202
Takeda Pharmaceutical Company NCT01931566

Last Updated: 05 Jan 2024


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News Citations

  1. Trial Updates: B Vitamin Back in Vogue? Diabetes Drug Less Sweet
  2. There’s No Tomorrow for TOMMORROW
  3. Can Phagocytosis, Memory Effects Revive Diabetes Meds?

Paper Citations

  1. . A randomized pilot clinical trial of the safety of pioglitazone in treatment of patients with Alzheimer disease. Arch Neurol. 2011 Jan;68(1):45-50. PubMed.
  2. . Efficacy of PPAR-γ agonist pioglitazone in mild Alzheimer disease. Neurobiol Aging. 2011 Sep;32(9):1626-33. PubMed.
  3. . Pioglitazone improved cognition in a pilot study on patients with Alzheimer's disease and mild cognitive impairment with diabetes mellitus. J Am Geriatr Soc. 2009 Jan;57(1):177-9. PubMed.
  4. . The effect of rosiglitazone on LRP1 expression and amyloid β uptake in human brain microvascular endothelial cells: a possible role of a low-dose thiazolidinedione for dementia treatment. Int J Neuropsychopharmacol. 2011 Nov 1;:1-8. PubMed.
  5. . Safety and efficacy of pioglitazone for the delay of cognitive impairment in people at risk of Alzheimer's disease (TOMMORROW): a prognostic biomarker study and a phase 3, randomised, double-blind, placebo-controlled trial. Lancet Neurol. 2021 Jul;20(7):537-547. PubMed.
  6. . PPARγ/RXRα-induced and CD36-mediated microglial amyloid-β phagocytosis results in cognitive improvement in amyloid precursor protein/presenilin 1 mice. J Neurosci. 2012 Nov 28;32(48):17321-31. PubMed.
  7. . Mechanisms underlying the rapid peroxisome proliferator-activated receptor-γ-mediated amyloid clearance and reversal of cognitive deficits in a murine model of Alzheimer's disease. J Neurosci. 2012 Jul 25;32(30):10117-28. PubMed.

Other Citations

  1. Aug 2013 conference story

External Citations


Further Reading


  1. . Using genetics to enable studies on the prevention of Alzheimer's disease. Clin Pharmacol Ther. 2013 Feb;93(2):177-85. PubMed.
  2. . Rosiglitazone and pioglitazone for the treatment of Alzheimer's disease. Ann Pharmacother. 2011 Nov;45(11):1416-24. PubMed.
  3. . Pioglitazone improves reversal learning and exerts mixed cerebrovascular effects in a mouse model of Alzheimer's disease with combined amyloid-β and cerebrovascular pathology. PLoS One. 2013;8(7):e68612. Print 2013 PubMed.
  4. . Long-term pioglitazone treatment improves learning and attenuates pathological markers in a mouse model of Alzheimer's disease. J Alzheimers Dis. 2012;30(4):943-61. PubMed.
  5. . The Nuclear Receptor PPARgamma as a Therapeutic Target for Cerebrovascular and Brain Dysfunction in Alzheimer's Disease. Front Aging Neurosci. 2010;2 PubMed.
  6. . Effects of long-term pioglitazone treatment on peripheral and central markers of aging. PLoS One. 2010;5(4):e10405. PubMed.
  7. . Pioglitazone does not increase cerebral glucose utilisation in a murine model of Alzheimer's disease and decreases it in wild-type mice. Diabetologia. 2006 Sep;49(9):2153-61. PubMed.
  8. . Pioglitazone for prevention of cognitive impairment: results and lessons. Lancet Neurol. 2021 Jul;20(7):500-502. PubMed.
  9. . The TOMMORROW study: Design of an Alzheimer's disease delay-of-onset clinical trial. Alzheimers Dement (N Y). 2019;5:661-670. Epub 2019 Oct 28 PubMed.
  10. . Drug Repositioning of Pioglitazone in Management and Improving the Cognitive Function among the Patients With Mild to Moderate Alzheimer's Disease: A Systematic Review and Meta-Analysis. Neurol India. 2023;71(6):1132-1141. PubMed.