43 compounds were read against these 2 conditions; 8 produced a graded row. The other 35 are named further down.

The ranking, and the key it uses

Ordered by the best rung the compound holds anywhere in this goal; then by what that study measured; then by how many graded rows it holds here, as a tie-break only; then by name. There is no blended score — one number mixing the rung and what was measured would invent a third scale nothing was graded against. Every rung links to the rubric that assigned it.

1. 01

   NAD+ Boosting / Precursor Peptides

   human RCT · direct outcome · 2 graded rows across 2 of 2 conditions

   Mild cognitive impairment · Cognitive performance in healthy adults

   2 graded rows, 2 sources

   1. Mild cognitive impairment

      human RCT Direct outcome Not approved for this condition

      Who was studied

      adults over 55 with subjective cognitive decline or mild cognitive impairment, n=46 randomised and 37 completing, nicotinamide riboside 1 g/day for 8 weeks in a double-blind placebo-controlled crossover; sex distribution and mean age not reported in the abstract

      The Repeatable Battery for the Assessment of Neuropsychological Status was the primary outcome and did not differ between nicotinamide riboside and placebo, and neither did Lumosity gameplay scores; plasma p-tau217 fell 7% on nicotinamide riboside against an 18% rise on placebo (p=0.02). Two further randomised placebo-controlled trials in mild cognitive impairment agree on the cognitive result: 1 g/day for 10 weeks in 20 patients left the Montreal Cognitive Assessment and every other neurocognitive metric unchanged while raising blood NAD+ 2.6-fold, and a 12-week trial in 42 patients with amnestic mild cognitive impairment doubled blood NAD+ with no improvement in its primary cognitive outcome. All three administered nicotinamide riboside; no trial of nicotinamide mononucleotide in this population is on file.

      Source PubMed 3 primary sources read for this row

   2. Cognitive performance in healthy adults

      human RCT Mechanistic only Not approved for this condition

      Who was studied

      healthy middle-aged adults, n=80, mean age 49.4 plus or minus 6.8 years, randomised to placebo or nicotinamide mononucleotide 300, 600 or 900 mg once daily for 60 days; a second trial gave 36 healthy middle-aged adults 250 mg/day for 12 weeks

      Recorded, and not evidence for this condition

      The dose-ranging trial measured blood NAD+, a six-minute walking test, a blood biological-age calculator, HOMA-IR, SF-36 and safety laboratory values, and the 12-week trial measured NAD+ metabolites and pulse wave velocity. Neither administered a cognitive or memory test, so no study measured cognitive performance in healthy adults and the step from a higher NAD+ concentration to better thinking is a mechanistic argument rather than a result. Where cognition has been measured, it was in people with mild cognitive impairment or subjective cognitive decline, the molecule was nicotinamide riboside rather than nicotinamide mononucleotide, and RBANS and MoCA scores did not change.

      Source PubMed 3 primary sources read for this row

2. 02

   Testosterone

   human RCT · direct outcome · 2 graded rows across 2 of 2 conditions

   Cognitive performance in healthy adults · Mild cognitive impairment

   2 graded rows, 2 sources

   1. Cognitive performance in healthy adults

      human RCT Direct outcome Not approved for this condition

      Who was studied

      cognitively healthy older men aged 60-80, pooled across 14 randomised trials published between 1990 and 2018; men with dementia or mild cognitive impairment were excluded, women were not studied, and the pooled participant total is not stated in the abstract

      A meta-analysis of 14 randomised trials in cognitively healthy older men reported small effects on a global cognitive composite (Hedges g=0.18, 95% CI 0.02 to 0.33), psychomotor speed (g=0.22, 95% CI 0.01 to 0.43) and executive function (g=0.15, 95% CI 0.03 to 0.28), and those are the figures that remain after two trials in which testosterone did not actually rise were removed from the pool. Attention, verbal memory, visuospatial ability and visuospatial memory were also analysed. Individual trials in this population have been null: 237 men aged 60-80 given testosterone undecanoate for 6 months showed no change across eight cognitive instruments, and 46 men aged 65-83 given 200 mg intramuscularly every two weeks for 36 months showed none either. No regulator has approved testosterone for cognition in either sex.

      Source PubMed 3 primary sources read for this row

   2. Mild cognitive impairment

      human RCT Direct outcome Not approved for this condition

      Who was studied

      men aged 65 and over with low serum testosterone on two measurements and age-associated memory impairment, n=493 of the 788 men randomised, mean age 72.3 years (SD 5.8), 12 months of 1% testosterone gel titrated to a target of 500-800 ng/dL; women were not enrolled

      The Cognitive Function Trial of the Testosterone Trials measured delayed paragraph recall as its primary outcome and found no difference from placebo at 6 or 12 months (adjusted difference -0.07, 95% CI -0.92 to 0.79, p=0.88). Visual memory on the Benton Visual Retention Test (p=0.24), executive function on Trail Making B minus A (p=0.14) and spatial ability on the Card Rotation Test (p=0.89) did not differ either. Entry required both a subjective memory complaint and objective memory more than 1 SD below men aged 20-24, so this is the impaired-memory population rather than a healthy one; testosterone products are approved for male hypogonadism and no regulator has approved testosterone for memory or cognition.

      Source PubMed Central 1 primary source read for this row

3. 03

   N-Acetylcysteine (NAC)

   human RCT · direct outcome · 1 graded row across 1 of 2 conditions

   Mild cognitive impairment

   1 graded row, 1 source

   1. Mild cognitive impairment

      human RCT Direct outcome Not approved for this condition

      Who was studied

      adults with vascular mild cognitive impairment enrolled in an exercise-based cardiac rehabilitation programme, n=59, 69.5% male, mean age 67.6 years, 2,400 mg/day orally for 24 weeks

      This 24-week randomised, double-blind, placebo-controlled trial measured an executive function composite plus verbal memory, working memory, non-verbal memory, attention and global cognition. Executive function improved over time in both arms and there was no significant difference between N-acetylcysteine and placebo (p=0.8), so the improvement belongs to the rehabilitation both groups received rather than to the compound. A companion imaging analysis of the same trial reported that lower frontal white-matter hyperintensity volume predicted greater Trail Making Test B improvement at 3 months on N-acetylcysteine than on placebo, with no difference at 6 months or on the other measures. N-acetylcysteine is approved as a mucolytic and as the paracetamol-overdose antidote; no regulator has approved it for a cognitive indication.

      Source PubMed 2 primary sources read for this row

4. 04

   Oxytocin

   human RCT · direct outcome · 1 graded row across 1 of 2 conditions

   Cognitive performance in healthy adults

   1 graded row, 1 source

   1. Cognitive performance in healthy adults

      human RCT Direct outcome Not approved for this condition

      Who was studied

      healthy women, n=437 pooled from two randomised double-blind placebo-controlled studies, a single 24 IU intranasal dose given either 40 minutes before or immediately after a film paradigm, with recognition tested 7 days later; age not reported in the abstract

      Forced-choice recognition memory did not differ between oxytocin and placebo for any scene type (F(2,401)=0.49, p=0.61), while memory for peri-event details was better than for other details in both arms (p<0.001). A separate randomised double-blind placebo-controlled study in 100 healthy male students gave the same 24 IU dose during an interference-inhibition working-memory task and found no effect on behavioural performance, with differences confined to event-related potential components. Both are single doses in a laboratory paradigm rather than a course of treatment; oxytocin is approved for obstetric use and no regulator has approved it for cognition.

      Source PubMed 2 primary sources read for this row

5. 05

   PEA

   human RCT · direct outcome · 1 graded row across 1 of 2 conditions

   Cognitive performance in healthy adults

   1 graded row, 1 source

   1. Cognitive performance in healthy adults

      human RCT Direct outcome Not approved for this condition

      Who was studied

      healthy young adults, n=39 randomised and completing, 700 mg/day of a formulated palmitoylethanolamide (Levagen+) for 6 weeks in a double-blind placebo-controlled crossover; sex distribution and age range not reported in the abstract

      On the Paired Associates Learning task the palmitoylethanolamide arm made fewer errors (p=0.0287, d=-0.47) while the first-success measure did not reach significance (p=0.142, d=0.54), and serum BDNF rose (p=0.0057, d=0.62). This is a single six-week crossover in 39 people, funded by the ingredient's manufacturer, and the abstract does not list the rest of the battery or which measures did not move, so how much of the test set is being reported cannot be checked. No replication in healthy adults is on file.

      Source PubMed 1 primary source read for this row

6. 06

   Cerebrolysin

   human observational · direct outcome · 1 graded row across 1 of 2 conditions

   Mild cognitive impairment

   1 graded row, 1 source

   1. Mild cognitive impairment

      human observational Direct outcome Not approved for this condition

      Who was studied

      elderly patients with amnestic mild cognitive impairment, n=100 (50 given annual courses of 20 intravenous infusions of 20 mL over 4 weeks, 50 observed without therapy), followed 3 years with annual examinations; sex distribution and mean age not reported in the abstract

      The one located study in this population reported a lower conversion rate to dementia and less progression of cognitive deficit in the treated group over three years, and its authors describe the effect as disease-modifying. Allocation was open and not randomised and there was no placebo arm, so the untreated group differs from the treated one by whatever decided who was treated; the report is published in Russian and only the English abstract could be read, so the psychometric instruments and the numbers behind the result are not on file. Cerebrolysin has no FDA or EMA marketing authorisation, it is marketed under national registrations in Russia, China and elsewhere, and no regulator document naming mild cognitive impairment as an indication was located.

      Source PubMed 1 primary source read for this row

7. 07

   Selank

   human observational · mechanistic only · 1 graded row across 1 of 2 conditions

   Cognitive performance in healthy adults

   1 graded row, 1 source

   1. Cognitive performance in healthy adults

      human observational Mechanistic only Not approved for this condition

      Who was studied

      healthy participants, n=52, allocated to selank, semax or placebo and imaged before dosing and at 5 and 20 minutes; sex, age, dose and route are not reported in the abstract

      Recorded, and not evidence for this condition

      Resting-state functional MRI compared whole-brain connectivity seeded on the amygdala and the dorsolateral prefrontal cortex, and reported different connectivity between the right amygdala and right temporal regions for selank and for semax against placebo. No cognitive or behavioural test was administered, so no study measured cognitive performance in this population. The abstract reports neither randomisation nor blinding, which is why this is graded as observational. A separate trial did administer Stroop and verbal fluency tests alongside selank, but in 70 patients with anxiety disorders rather than in healthy adults.

      Source PubMed 2 primary sources read for this row

8. 08

   Semax

   human observational · mechanistic only · 1 graded row across 1 of 2 conditions

   Cognitive performance in healthy adults

   1 graded row, 1 source

   1. Cognitive performance in healthy adults

      human observational Mechanistic only Not approved for this condition

      Who was studied

      healthy volunteers, n=24 (11 men and 13 women, mean age 43.9 plus or minus 9.5 years), 14 given intranasal 1% semax and 10 given placebo, imaged before dosing and again at 5 and 20 minutes

      Recorded, and not evidence for this condition

      Resting-state functional MRI found a larger rostral, medial frontal cortex subcomponent of the default mode network in the semax group than in the controls. No cognitive or behavioural test was administered, so no study here measured cognitive performance and the step from a network map to sharper thinking is an argument rather than a result. The abstract does not state that allocation was randomised or that anyone was blinded, which is why this is graded as observational rather than as a randomised trial. There is no FDA or EMA marketing authorisation, and no approval anywhere for use by healthy people to improve cognition is on file.

      Source PubMed 1 primary source read for this row

Checked, and nothing on file

35 compounds were read against these conditions and produced no gradeable row. They are named here rather than left off, because a list of 8 reads identically whether 8 survived 43 or 8 were all anyone thought of.

1. Adamax on cognitive performance in healthy adults

   No rung — nothing on file to grade Not approved for this condition

   Adamax is sold as a semax-family compound for focus and drive. No study of it in humans or in animals could be located: a PubMed search on the name returns only papers using the unrelated Adamax optimisation algorithm in machine learning. The corpus record carries no citations at all, and nothing measuring attention, memory or any other cognitive outcome exists on file for it.

2. Angiotensin II

   No rung — nothing on file to grade

   Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

3. Bombesin

   No rung — nothing on file to grade

   Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

4. C-Max

   No rung — nothing on file to grade

   Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

5. Carnosic Acid

   No rung — nothing on file to grade

   Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

6. Cholecystokinin (CCK)

   No rung — nothing on file to grade

   Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

7. Cortexin

   No rung — nothing on file to grade

   Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

8. CRH (Corticotropin-Releasing Hormone) on cognitive performance in healthy adults

   No rung — nothing on file to grade Not approved for this condition

   Nothing located with an administered dose and a cognitive outcome.

9. CRH (Corticotropin-Releasing Hormone) on mild cognitive impairment

   No rung — nothing on file to grade Not approved for this condition

   Nothing located. CRH and its receptors are studied in Alzheimer's tissue as pathology, not given as treatment.

10. Dihexa on cognitive performance in healthy adults

    No rung — nothing on file to grade Not approved for this condition

    Dihexa is sold for focus and memory and has never been given to a human being in any published study, so nothing about it has been measured in people at all. The record is rodent and cell work, and the 2014 paper in the Journal of Pharmacology and Experimental Therapeutics behind the procognitive claim carried an expression of concern in 2021 and was retracted in April 2025.

11. Dihexa on mild cognitive impairment

    No rung — nothing on file to grade Not approved for this condition

    Dihexa is sold for memory and no human study of it exists on file, in mild cognitive impairment or in any other population. The published record is rodent and cell work, and the 2014 paper in the Journal of Pharmacology and Experimental Therapeutics that established the procognitive claim carried an expression of concern in 2021 and was retracted in April 2025, which removes the study most often cited for it. The remaining animal work is in scopolamine-treated and aged rats and in APP/PS1 mice, which are models of dementia rather than of mild cognitive impairment.

12. Dynorphin A

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

13. Epitalon

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

14. Galantide

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

15. GHRH (Growth Hormone-Releasing Hormone) on cognitive performance in healthy adults

    No rung — nothing on file to grade Not approved for this condition

    The controlled cognition trials in this family did not use native growth hormone-releasing hormone. The 152-participant randomised, double-blind, placebo-controlled trial of 20 weeks at 1 mg/day, and its magnetic resonance spectroscopy substudy, both administered tesamorelin, a stabilised analogue that is a separate compound in this corpus and holds the record. Nothing retrieved gave native GHRH over a course and measured cognition.

16. GHRH (Growth Hormone-Releasing Hormone) on mild cognitive impairment

    No rung — nothing on file to grade Not approved for this condition

    Same reason as above: the mild cognitive impairment arms of those trials received tesamorelin, not native GHRH, so the row belongs to that compound.

17. GHRP-1 on cognitive performance in healthy adults

    No rung — nothing on file to grade Not approved for this condition

    No trial has used this compound against this condition; no cognitive endpoint was measured in any GHRP-1 study retrieved.

18. GHRP-2 on cognitive performance in healthy adults

    No rung — nothing on file to grade Not approved for this condition

    No trial has used this compound against this condition; no cognitive endpoint was measured in any retrieved GHRP-2 study.

19. GHRP-6 on cognitive performance in healthy adults

    No rung — nothing on file to grade Not approved for this condition

    No trial has used this compound against this condition; no cognitive endpoint was measured outside the ischaemic-injury models recorded under stroke.

20. Hexarelin on cognitive performance in healthy adults

    No rung — nothing on file to grade Not approved for this condition

    No trial has used this compound against this condition; no cognitive endpoint was measured in any retrieved hexarelin study.

21. Humanin

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

22. IGF-1 on mild cognitive impairment

    No rung — nothing on file to grade Not approved for this condition

    No trial has administered IGF-I to a cognitively impaired population. The IGF-I cognition literature is observational — blood IGF-I measured as a correlate, not given as a treatment.

23. Irisin

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

24. Leu-Enkephalin

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

25. Met-Enkephalin

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

26. Nesfatin-1

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

27. Neurotensin

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

28. Nociceptin

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

29. Noopept on cognitive performance in healthy adults

    No rung — nothing on file to grade Not approved for this condition

    Noopept is sold as a cognitive enhancer and no trial in healthy adults could be located. The only human reports are two comparative trials against piracetam in patients with cognitive impairment of vascular and traumatic origin, both indexed in PubMed without abstracts, so their design, size, doses and instruments could not be read. It is a proline-containing dipeptide ester rather than a peptide as sold; it is not approved by the FDA or the EMA, and a Russian registration is widely asserted but no regulator document was located.

30. Noopept on mild cognitive impairment

    No rung — nothing on file to grade Not approved for this condition

    Two comparative trials against piracetam in patients with mild-to-moderate cognitive impairment of vascular and traumatic origin are indexed in PubMed without abstracts, so the design, the number of patients, the doses and the rating instruments could not be read and no rung can honestly be attached to them. No trial in amnestic mild cognitive impairment and no placebo-controlled trial in any cognitive population could be located. Noopept is a proline-containing dipeptide ester rather than a peptide as sold; it is not approved by the FDA or the EMA, and a Russian registration is widely asserted but no regulator document was located.

31. Orexin-A

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

32. P21 on mild cognitive impairment

    No rung — nothing on file to grade Not approved for this condition

    Every located study of P021, the adamantylated tetrapeptide Ac-DGGLAG-NH2, is in mice or rats: 3xTg-AD and Ts65Dn mouse models, a Cdkl5 knockout model and aged rats. No human study of any kind is on file, and none of the animal work models mild cognitive impairment. Part of the literature attributed to this record concerns Peptide 6, the longer ciliary neurotrophic factor fragment P021 was derived from, which is a different and longer molecule.

33. PACAP (Pituitary Adenylate Cyclase-Activating Peptide)

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

34. Pinealon on cognitive performance in healthy adults

    No rung — nothing on file to grade Not approved for this condition

    Pinealon is positioned for cognitive resilience and no human study of it exists on file. What is on file is a cell-viability experiment and a rat study of hypothalamic noradrenaline under hyperhomocysteinaemia; neither measured cognitive performance, and no trial in healthy adults could be located. Epitalon, the other pineal tetrapeptide in this corpus, is in the same position: cell lines, fruit flies and rodents, with no human cognitive study on file.

35. Simonson Alpha 1

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

36. Substance P

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

37. Vasopressin on cognitive performance in healthy adults

    No rung — nothing on file to grade Not approved for this condition

    Small intranasal vasopressin studies exist in social cognition and memory paradigms, but no trial measuring a clinical cognitive outcome against placebo in healthy adults was retrieved that would support a row. Recorded as searched and empty rather than graded.

38. VIP

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

39. β-Endorphin

    No rung — nothing on file to grade

    Checked against cognitive performance in healthy adults, mild cognitive impairment. No study meeting the rubric was found for any of them.

Browse by goal

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