Name: Citalopram
Synonyms: escitalopram, Celexa, Lexapro , Cipralex
Chemical Name: (RS)-1-[3-(Dimethylamino)propyl]-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-carbonitrile
Therapy Type: Small Molecule (timeline)
Target Type: Other Neurotransmitters (timeline)
Condition(s): Alzheimer's Disease, Preclinical Alzheimer's Disease
U.S. FDA Status: Alzheimer's Disease (Phase 3), Preclinical Alzheimer's Disease (Inactive)
Approved for: Depression, generalized anxiety disorder


Citalopram is a selective serotonin reuptake inhibitor used to treat depression and anxiety. It is a chiral molecule that exists as two enantiomers. Citalopram consists of a 1:1 mixture of (R)- and (S)-stereoisomers. A purified (S)-isomer formulation, marketed as Escitalopram, is approved to treat depression and generalized anxiety disorder. Both are available as generics. Both work by increasing serotonin activity in the brain. Escitalopram is considered superior at treating depression, with faster onset at lower doses than citalopram (Lepola et al., 2004Gartlehner et al., 2011). Side effects in older adults include abnormal heart rhythm, loss of coordination, and bleeding.

Many people with Alzheimer’s disease have noncognitive symptoms, which add to their and caregivers’ burdens. Agitation, including disruptive or aggressive behaviors, may stem from degeneration of serotonin systems. No treatments are approved for agitation in people with Alzheimer’s disease, but based on existing clinical evidence, citalopram and escitalopram are sometimes used (Aga 2019Kales et al., 2019).

Some research has suggested anti-amyloid actions for SSRIs. Activation of certain serotonin receptors reduces Aβ production by increasing non-amyloidogenic α-secretase processing of APP (Nitsch et al., 1996; Fisher et al., 2016).Citalopram was reported to lower Aβ production and amyloid plaque load in mice and people (Cirrito et al., 2011; Sheline et al., 2014; Zhang et al., 2018). However, in one study, escitalopram did not reduce brain Aβ in mice (von Linstow et al., 2017). More recently, escitalopram was found to increase hippocampal α-secretase activity by 50 percent, and reduce brain interstitial Aβ42 in mice (Cirrito et al., 2020). The same study showed chronic escitalopram halted plaque growth, but did not remove established plaques. In cognitively normal older people, two or eight weeks of treatment with escitalopram led to a 6 percent reduction in CSF Aβ42 concentrations, compared to a slight increase in placebo-treated volunteers (Sheline et al., 2020).

In ADNI participants with a history of depression, long-term use of SSRIs was linked to a three-year delay in progression to dementia (Bartels et al., 2018). Another study linked SSRI use in people with depression and MCI or AD to slowed cognitive decline, reduced progression of gray-matter atrophy, and a trend toward slower amyloid deposition (Brendel et al., 2018).


In the first placebo-controlled trial of citalopram for behavioral disturbances in people with AD, four weeks of citalopram led to decreased confusion, anxiety, and irritability (Nyth and Gottfries, 1990). A second randomized trial, in dementia patients hospitalized for agitation or psychosis symptoms, found citalopram taken for 17 days lessened agitation and aggression (Pollock et al., 2002). Citalopram or escitalopram improved agitation and psychosis as effectively as the typical antipsychotic risperidone, but with fewer side effects (Pollock et al., 2007Barak et al., 2011).

In July 2009, a group of academic investigators started a randomized study of citalopram. Called CitAD, it enrolled 186 participants with probable AD and agitation, and compared a nine-week course of psychosocial intervention plus 30 mg/day citalopram to psychosocial intervention plus placebo. Citalopram reduced agitation and caregiver distress compared with placebo, but caused cardiac side effects and cognitive worsening (Feb 2014 news; Dec 2014 conference news; Porsteinsson et al., 2014). Subsequent to this trial, the FDA established a safe limit for citalopram of 20 mg/day for people over 60 (Marcum et al., 2012).

An analysis of the blood concentrations of citalopram isomers associated cognitive worsening with the (R) isomer and clinical improvements with the (S) form (Ho et al., 2016). In January 2018, the same investigators began an NIA-funded Phase 3 trial of escitalopram. In the run-in phase, participants with AD and agitation receive a psychosocial intervention for three weeks. Those who do not improve are randomized to receive up to 15 mg/day escitalopram or placebo for three months, with continuing psychosocial intervention. The primary outcome in this pragmatic trial is a modified form of the ADCS-Clinical Global Impression of Change scale after 12 weeks. The trial will enroll 392 patients, and run through August 2022 (Ehrhardt et al., 2019).

A trial in South Korea evaluated 20 mg/day escitalopram for one year on AD progression in 74 people with probable AD, and found no difference in hippocampal or whole-brain volumes, and no benefit on cognitive, neuropsychiatric, or depression scores, compared with placebo (Choe et al., 2015). Another trial in South Korea, of a 12-week course of 15 mg/d escitalopram or placebo in 84 participants with a clinical diagnosis of AD, reported no differences outcomes of depression and cognition (An et al., 2017).

Starting in July 2017, a Phase 1 study at NYU began comparing 5 mg/d of escitalopram with 37.5 mg/d of venlafaxine, a different antidepressant medication, and with placebo, in 31 people with subjective memory concerns. The study was to evaluate the drugs' ability to slow down progression to mild cognitive impairment or Alzheimer's disease, using EEG and metabolic imaging in the hippocampal formation as primary outcome measures. This trial was terminated in September 2019 due to insufficient enrollment.

For details on citalopram and escitalopram trials in Alzheimer's disease, see

Last Updated: 24 Sep 2020


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News Citations

  1. Citalopram Calms Agitation in Alzheimer’s, but Carries Risks
  2. New Treatments for Alzheimer’s Behavioral Symptoms on Horizon

Paper Citations

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  4. . Escitalopram versus risperidone for the treatment of behavioral and psychotic symptoms associated with Alzheimer's disease: a randomized double-blind pilot study. Int Psychogeriatr. 2011 Apr 15;:1-5. PubMed.
  5. . Effect of citalopram on agitation in Alzheimer disease: the CitAD randomized clinical trial. JAMA. 2014 Feb 19;311(7):682-91. PubMed.
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  7. . R- and S-citalopram concentrations have differential effects on neuropsychiatric scores in elders with dementia and agitation. Br J Clin Pharmacol. 2016 Sep;82(3):784-92. Epub 2016 Jun 20 PubMed.
  8. . Escitalopram for agitation in Alzheimer's disease (S-CitAD): Methods and design of an investigator-initiated, randomized, controlled, multicenter clinical trial. Alzheimers Dement. 2019 Nov;15(11):1427-1436. Epub 2019 Oct 3 PubMed.
  9. . Multicenter, randomized, placebo-controlled, double-blind clinical trial of escitalopram on the progression-delaying effects in Alzheimer's disease. Int J Geriatr Psychiatry. 2015 Nov 9; PubMed.
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  13. . When and How to Treat Agitation in Alzheimer's Disease Dementia With Citalopram and Escitalopram. Am J Geriatr Psychiatry. 2019 Oct;27(10):1099-1107. Epub 2019 May 10 PubMed.
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  18. . An antidepressant decreases CSF Aβ production in healthy individuals and in transgenic AD mice. Sci Transl Med. 2014 May 14;6(236):236re4. PubMed.
  19. . Citalopram restores short-term memory deficit and non-cognitive behaviors in APP/PS1 mice while halting the advance of Alzheimer's disease-like pathology. Neuropharmacology. 2018 Mar 15;131:475-486. Epub 2017 Dec 11 PubMed.
  20. . Serotonin augmentation therapy by escitalopram has minimal effects on amyloid-β levels in early-stage Alzheimer's-like disease in mice. Alzheimers Res Ther. 2017 Sep 12;9(1):74. PubMed.
  21. . Effect of escitalopram on Aβ levels and plaque load in an Alzheimer mouse model. Neurology. 2020 Nov 10;95(19):e2666-e2674. Epub 2020 Sep 10 PubMed.
  22. . Effect of escitalopram dose and treatment duration on CSF Aβ levels in healthy older adults: A controlled clinical trial. Neurology. 2020 Nov 10;95(19):e2658-e2665. Epub 2020 Sep 10 PubMed.
  23. . Impact of SSRI Therapy on Risk of Conversion From Mild Cognitive Impairment to Alzheimer's Dementia in Individuals With Previous Depression. Am J Psychiatry. 2018 Mar 1;175(3):232-241. Epub 2017 Nov 28 PubMed.
  24. . Serotonin Selective Reuptake Inhibitor Treatment Improves Cognition and Grey Matter Atrophy but not Amyloid Burden During Two-Year Follow-Up in Mild Cognitive Impairment and Alzheimer's Disease Patients with Depressive Symptoms. J Alzheimers Dis. 2018;65(3):793-806. PubMed.

External Citations


Further Reading


  1. . Principal components analysis of agitation outcomes in Alzheimer's disease. J Psychiatr Res. 2016 Aug;79:4-7. Epub 2016 Apr 16 PubMed.
  2. . Characterizing Highly Benefited Patients in Randomized Clinical Trials. Int J Biostat. 2017 May 20;13(1) PubMed.
  3. . Heterogeneity of Treatment Response to Citalopram for Patients With Alzheimer's Disease With Aggression or Agitation: The CitAD Randomized Clinical Trial. Am J Psychiatry. 2016 May 1;173(5):465-72. Epub 2016 Jan 15 PubMed.
  4. . Sedation mediates part of Citalopram's effect on agitation in Alzheimer's disease. J Psychiatr Res. 2016 Mar;74:17-21. Epub 2015 Dec 12 PubMed.
  5. . Effects of Citalopram on Neuropsychiatric Symptoms in Alzheimer's Dementia: Evidence From the CitAD Study. Am J Psychiatry. 2016 May 1;173(5):473-80. Epub 2016 Apr 1 PubMed.
  6. . Sedation mediates part of Citalopram's effect on agitation in Alzheimer's disease. J Psychiatr Res. 2016 Mar;74:17-21. Epub 2015 Dec 12 PubMed.
  7. . Citalopram for the Treatment of Agitation in Alzheimer Dementia: Genetic Influences. J Geriatr Psychiatry Neurol. 2016 Mar;29(2):59-64. Epub 2015 Aug 23 PubMed.
  8. . Changes in QTc interval in the citalopram for agitation in Alzheimer's disease (CitAD) randomized trial. PLoS One. 2014;9(6):e98426. Epub 2014 Jun 10 PubMed.
  9. . Time to Response to Citalopram Treatment for Agitation in Alzheimer Disease. Am J Geriatr Psychiatry. 2015 Nov;23(11):1127-33. Epub 2015 May 19 PubMed.
  10. . The effect of treatment with selective serotonin reuptake inhibitors in comparison to placebo in the progression of dementia: a systematic review and meta-analysis. Age Ageing. 2016 Jul;45(4):448-56. Epub 2016 Apr 7 PubMed.
  11. . Serotonergic Function and Treatment of Behavioral and Psychological Symptoms of Frontotemporal Dementia. Am J Geriatr Psychiatry. 2011 Nov 4; PubMed.