L-Tryptophan After Surgery: No Help for Delirium in Older Adults

randomized-controlled-trial PMID: 25112175

L-Tryptophan After Surgery: No Help for Delirium in Older Adults

Quick Summary: A study tested if taking L-tryptophan after major surgery could prevent confusion and agitation, known as postoperative delirium, in older adults. Researchers gave the supplement to some patients and a fake pill to others, but it didn't lower the chances or length of delirium. This means L-tryptophan isn't a proven fix for this common surgery side effect.

What The Research Found

Scientists wanted to see if L-tryptophan, an amino acid that helps make serotonin in the brain (a chemical linked to mood and sleep), could fight off delirium after surgery. Delirium is a sudden state of confusion that often hits older people in the hospital, making them restless or mixed up.

Key results showed no real benefits:
- About 39% of all patients developed some form of delirium, no matter what they took.
- For the more active type of delirium (called excitatory, with lots of agitation), 17% in the L-tryptophan group got it, compared to 9% in the placebo group—but this difference wasn't strong enough to matter statistically.
- The time spent in excitatory delirium was almost the same: around 3 days for both groups.
- Overall delirium hit 40% of the L-tryptophan group and 37% of the placebo group, with lengths of about 2.9 days versus 2.4 days—again, no big difference.

In short, adding L-tryptophan after surgery didn't cut down delirium risks or how long it lasted.

Study Details

Who was studied: 325 men and women aged 60 or older, mostly veterans (about 88% men), having big elective surgeries like heart or joint operations that needed time in the intensive care unit (ICU) right after.
How long: Treatment started right after surgery and lasted up to 3 days, with doctors checking for delirium daily during that time.
What they took: The L-tryptophan group got 1 gram by mouth three times a day (total 3 grams daily). The placebo group got a look-alike fake pill with the same schedule. No one knew who got what to keep results fair.

They used simple tools like the Confusion Assessment Method for the ICU (CAM-ICU) to spot delirium and rate agitation levels.

What This Means For You

If you're an older adult facing major surgery, this study suggests L-tryptophan supplements right after won't help prevent or shorten delirium episodes. Delirium can make recovery tougher, leading to longer hospital stays or falls, so talk to your doctor about proven ways to lower risks—like staying active early, managing pain well, or getting enough sleep.

Don't start L-tryptophan on your own for surgery prep; this research shows it didn't work here. For general mood or sleep support (since it boosts serotonin), check with a healthcare pro first, especially if you're over 60 or have health issues. Focus on doctor-recommended steps for a smoother recovery.

Study Limitations

This research has some caveats to keep in mind:
- Most participants were older male veterans, so results might not apply as well to women, younger folks, or non-veterans.
- They only started the supplement after surgery, which might miss a chance to help before problems start.
- The 3-day treatment was short, so it doesn't tell us about longer use or effects beyond the hospital.
- The study might not have caught small benefits in certain groups because of its size.
- Safety info was limited—no major side effects noted, but more checks are needed for everyday use.

Overall, while L-tryptophan shows promise in lab tests for brain health, this real-world trial says it's not the answer for postoperative delirium yet.

Key Findings

This randomized controlled trial (RCT) found that postoperative L-tryptophan supplementation (1g three times daily) did not significantly reduce the incidence or duration of delirium in elderly patients undergoing major elective surgery requiring ICU admission. Excitatory delirium occurred in 17% of the tryptophan group vs. 9% in placebo (p=0.18), with similar durations (3.3±1.7 vs. 3.1±1.9 days, p=0.74). Overall delirium incidence was 40% vs. 37% (p=0.60), and duration was 2.9±1.8 vs. 2.4±1.6 days (p=0.17).

Study Design

The study was a randomized, double-blind, placebo-controlled trial conducted at the Denver Veterans Affairs Medical Center. Participants included 325 adults aged ≥60 years undergoing major elective surgery with planned ICU admission. Delirium was assessed using the CAM-ICU and Richmond Agitation and Sedation Scale. Follow-up occurred for up to 3 days post-surgery.

Dosage & Administration

The intervention group received 1g of L-tryptophan orally three times daily, starting post-surgery and continuing for ≤3 days. The placebo group received identical dosing. Supplements were administered in a double-blind manner, ensuring neither participants nor staff knew group assignments.

Results & Efficacy

Primary Outcome: Excitatory delirium incidence was higher in the tryptophan group (17% vs. 9%), but not statistically significant (p=0.18). Duration of excitatory delirium was nearly identical (3.3 vs. 3.1 days, p=0.74).
Secondary Outcomes: Overall delirium incidence (40% vs. 37%, p=0.60) and duration (2.9 vs. 2.4 days, p=0.17) showed no significant between-group differences.
Confidence Intervals: The overall delirium incidence had a 95% CI of 34–44%, with no clear effect of tryptophan.

Limitations

Sample Heterogeneity: Participants were predominantly male veterans (88%), limiting generalizability to other demographics.
Timing of Intervention: Supplementation began post-surgery, potentially missing a critical window for prophylactic effects.
Short Duration: Only 3 days of supplementation may be insufficient to capture long-term cognitive impacts.
Underpowered Subgroup Analysis: The study may lack power to detect smaller effects in specific delirium subtypes.
Adverse Event Reporting: No significant differences in adverse events were reported, but safety data were limited.

Clinical Relevance

These findings suggest that L-tryptophan (3g/day total dose) administered post-surgery does not effectively mitigate delirium risk or severity in elderly ICU patients. While preclinical evidence links tryptophan to serotonin regulation and cognitive function, this trial does not support its use for postoperative delirium prevention in this population. Clinicians should prioritize established delirium prevention strategies (e.g., early mobilization, pain management) over tryptophan supplementation in similar surgical ICU settings. Patients considering tryptophan for cognitive health should consult healthcare providers, as this study found no benefit in acute postoperative contexts.

Word Count: 398