We aim to assess the neurocognitive mechanisms of tyrosine supplementation in older adults during different forms of cognitive control depending on the prefrontal cortex: working memory, reactive and proactive response inhibition, and effort…
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Source
Brief title
Condition
- Other condition
Synonym
Health condition
gezonde veroudering
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
We will assess the effect of the intervention on BOLD signal measured with
functional magnetic resonance imaging (fMRI) and response times and accuracy on
the computerized tasks during fMRI.
Secondary outcome
Secondarily, effects on paper and pencil neuropsychological tasks will be
assessed. Also, intervention effects on subjective measurements (e.g.
self-report questionnaires, visual analogue scales), on catecholamine and
serotonin metabolites (MVA - metanefrine, HVA - normetinefrine, HVA - 3-MT and
5-HIAA) in urine samples, and on physiological recordings (blood pressure,
heart rate) will be measured.
Background summary
In this study, we aim to investigate the neurocognitive mechanism of the food
supplement tyrosine in healthy older adults. The aging brain has a shortage of
dopamine, especially in the prefrontal cortex. The amino acid tyrosine, a
precursor of dopamine, has been shown to reduce cognitive impairments in young
adults during environmental stress such as cold induction, acoustic noise or a
demanding task. The suggested mechanism behind this effect is that stress
depletes dopamine and noradrenaline in the brain, which can be repleted by
tyrosine. Tyrosine supplementation could possibly also replete dopamine levels
in the aging brain, thereby improving prefrontal cortex functioning and
associated cognition.
Study objective
We aim to assess the neurocognitive mechanisms of tyrosine supplementation in
older adults during different forms of cognitive control depending on the
prefrontal cortex: working memory, reactive and proactive response inhibition,
and effort discounting.
Study design
We will use a double blind, counterbalanced, placebo-controlled, within-subject
study design. Subjects will be tested twice using fMRI, once on placebo and
once on tyrosine supplementation, and will be pre-screened during an intake
session.
Intervention
Subjects will receive either 150 mg/kg body weight tyrosine or 50 mg/kg body
weight Fantomalt diet carbohydrate powder mixed with 100 mg/kg cornstarch
(placebo condition), in both cases dissolved in 200 grams of flavoured light
yoghurt on two different test days.
Study burden and risks
Subjects will come to the lab three times: once for 2,5 hour intake session and
two times for 4 hour and 10 minutes testing session (of which 100 minutes tasks
during fMRI). After dinner on the evening prior to and on the morning of the
test session, subjects have to refrain from eating, drinking coffee or other
stimulant containing drinks, as well as alcohol. Furthermore, during this time
period subjects have to adhere to some simple restrictions with respect to
medication and drug intake. The dosage of tyrosine can be administered safely
to healthy humans without any known risk of serious adverse events.
Kapittelweg 29
Nijmegen 6525EN
NL
Kapittelweg 29
Nijmegen 6525EN
NL
Listed location countries
Age
Inclusion criteria
Inclusion criteria (zie sectie 4.2 op pagina 12 van het protocol)
In order to be eligible to participate in this study, subjects must meet all of these criteria:
- Age: 60-75 years old
- Proficient knowledge of the Dutch language
- Right-handed
- Willing to perform tasks in the MRI scanner, to come to the centre on three occasions, consuming tyrosine or a placebo and willing to fast the night before the two test sessions.
Exclusion criteria
Exclusion criteria (see section 4.3 on page 12 of the protocol)
A potential subject who meets any of the following criteria will be excluded from participation in this study (for a checklist see F1 Intake Questionnaires and Checklists):
- Mini Mental State Examination score < 24
- HADS score > 11
- Estimated IQ < 85 (based on Nederlandse Leestest voor Volwassenen (NLV) -score)
- (History of) clinically significant psychiatric disorder
- (History of) clinically significant neurological disorder, such as brain infarct, Parkinson*s Disease, chronic migraine, Diabetes Mellitus
- First degree family history of schizophrenia, bipolar disorder or major depressive disorder
- Thyroid problems and low-protein diet
- Daily use of beta blockers
- Using medication that can interfere with tyrosine*s action; monoamine oxidase inhibitors and other antidepressants, sympathomimetic amines, and opioids
- General medical conditions, such as repetitive strain injury (RSI) or sensori-motor handicaps, blindness or colorblindness, as judged by the investigator
- (History of) abuse of drugs or alcohol
- Habitual smoking, i.e. more than a pack of cigarettes per week
- Participation, current or within the past twelve months, in a specific cognitive training study
- Contra-indications for MRI:
o Metal objects or fragments in the body that cannot be taken out
o Active implants in the body
o Using medical plasters
o Epilepsy
o Previous head surgery
o Claustrophobia
Design
Recruitment
Followed up by the following (possibly more current) registration
No registrations found.
Other (possibly less up-to-date) registrations in this register
In other registers
| Register | ID |
|---|---|
| CCMO | NL49758.091.14 |
| OMON | NL-OMON22035 |