The primary objective is to choose the dose (100, 150 or 200 mg/kg body weight) of tyrosine that shows the highest increase in plasma tyrosine concentration, based on comparison of the dose-response curves, in elderly. These dose-response curves…
ID
Source
Brief title
Condition
- Disturbances in thinking and perception
Synonym
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
The primary study parameter is tyrosine plasma concentration at T0, T90, T120,
T150, T180, T210 and T240.
Secondary outcome
The secondary study parameter is performance on the n-back working memory task
measured by accuracy (total number of hits) and reaction time (ms).
Background summary
Dopamine neurons in the prefrontal cortex, a brain region involved in working
memory, are highly tyrosine-dependent. Both prefrontal dopamine availability
and working memory performance decline in the aging brain and therefore elderly
might benefit from tyrosine supplementation. However, to study the effect of
tyrosine supplementation on working memory performance in elderly, it is
important to have sufficient insight in the plasma response following different
doses of tyrosine administration. Additionally, it is important to examine
changes in working memory performance following different doses of tyrosine
administration.
Study objective
The primary objective is to choose the dose (100, 150 or 200 mg/kg body weight)
of tyrosine that shows the highest increase in plasma tyrosine concentration,
based on comparison of the dose-response curves, in elderly. These
dose-response curves will be compared with a reference dose-response curve for
150 mg/kg body weight tyrosine in young people. The secondary objective is to
determine the association between the dose of tyrosine and performance on a
working memory task, as an indication of the central usage and subsequent
cognitive benefit of the peripheral supply measured by plasma tyrosine
concentrations.
Study design
This study has a double-blind, randomized, cross-over design with three
conditions for the elderly participants and one condition for the younger
participants.
Intervention
Elderly participants receive three doses (100, 150 and 200 mg/kg bodyweight) of
tyrosine and younger participants receive one dose (150 mg/kg body weight) of
tyrosine. Tyrosine will be mixed with yoghurt.
Study burden and risks
A test session comprises consumption of the tyrosine with yoghurt and taking
seven blood samples with Venflon. Elderly participants will have three test
sessions, younger participants will have one test session. The doses of
tyrosine used in this study have shown to be safe in previous studies. The
risks involved in participating in this study are minimal. The risk of the
blood collection is that of a small local hematoma, feeling light-headed,
fainting or an infection.
Bomenweg 4
Wageningen 6703HD
NL
Bomenweg 4
Wageningen 6703HD
NL
Listed location countries
Age
Inclusion criteria
• Aged 18-35 years or aged 60-75 years
• Normal and stable weight (BMI 18.5-25 kg/m2 and weight 50-95 kg)
• Willing to abstain from blood donation during the study
• Dutch-speaking
• Non-smoking
• Normal or corrected-to-normal vision
Exclusion criteria
• Thyroid problems, such as hyperthyroidism, hypothyroidism, thyroid cancer
• Using medication that can interfere with tyrosine*s action; monoamine oxidase inhibitors and other antidepressants, sympathomimetic amines, and opioids
• Following a low-protein diet as prescribed by a dietician or physician
• Parkinson*s Disease
• Depression
• Use of tyrosine supplements
• Being allergic or having a dislike to the product carrier (banana-flavored yoghurt)
• Bad venous access, as judged by the research nurse
• Mini Mental State Examination (MMSE) score < 24 (to exclude cognitive impaired participants, only for elderly participants)
• 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, chronic migraine, major depression
• Under treatment for cardiac or vascular diseases and use of medication for these conditions
• General medical conditions, such as repetitive strain injury (RSI) or sensori-motor handicaps, as judged by the investigator
• Alcohol consumption of more than 14 (women) or 21 (men) units per week
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 | NL49893.081.14 |
| OMON | NL-OMON23338 |