We aim to assess the effects of tyrosine supplementation on prefrontal brain activation, as measured by a combination of fNIRS and EEG, during response inhibition and working-memory performance in older adults. We will also assess whether…
ID
Source
Brief title
Condition
- Other condition
- Cognitive and attention disorders and disturbances
Synonym
Health condition
cognitieve achteruitgang
Research involving
Sponsors and support
Intervention
Outcome measures
Primary outcome
Changes in functional prefrontal activation as determined by oxygenated
hemoglobin changes (µmol/L) induced by tyrosine supplementation, measured
during response inhibition performance.
Secondary outcome
- Changes in functional prefrontal activation as determined by oxygenated
hemoglobin changes (µmol/L) induced by tyrosine supplementation, measured
during working memory performance.
- Changes in functional prefrontal activation as determined by deoxygenated
hemoglobin changes (µmol/L) induced by tyrosine supplementation, measured
during response inhibition performance and working memory performance.
- Changes in brain activity as determined by EEG frequency bands, induced by
tyrosine supplementation, measured during response inhibition performance.
- Effect of blood pressure (mmHg), exhaled CO2 (%) and heart rate on the
oxygenated and deoxygenated hemoglobin changes.
- Changes in behavioural performance on the response inhibition and working
memory tasks, induced by tyrosine supplementation (preparatory slowing and
stop-signal reaction time of stop-signal task and accuracy and reaction time of
n-back task.
- Changes in performance on the neuropsychological test battery, induced by
tyrosine supplementation.
Background summary
Dopamine neurons in the prefrontal cortex, a brain region involved in response
inhibition and working memory, are highly tyrosine-dependent. The amino acid
tyrosine is a precursor of dopamine and has been shown to reduce cognitive
impairments in young adults during environmental stress such as cold induction,
acoustic noise or a demanding task. Both prefrontal dopamine availability and
prefrontal brain activity decline in the aging brain and therefore elderly
might also benefit from tyrosine supplementation to improve cognitive
functioning.
Study objective
We aim to assess the effects of tyrosine supplementation on prefrontal brain
activation, as measured by a combination of fNIRS and EEG, during response
inhibition and working-memory performance in older adults. We will also assess
whether neuropsychological functioning - as measured by paper and pencil tests
- will improve due to tyrosine supplementation.
Study design
We will use a double-blind, placebo-controlled, counterbalanced within-subject
study design. Subjects will be tested twice using fNIRS-EEG, once on tyrosine
supplementation and once on placebo, and will be pre-screened during an intake
session.
Intervention
Subjects will receive 150 mg/kg body weight L-tyrosine powder or 50 mg/kg body
weight of dextrin-maltose with 100 mg/kg cornstarch (placebo condition) in a
randomized order. Both interventions will be dissolved in 200 grams of
flavoured light banana flavored yoghurt on different test days.
Study burden and risks
Subjects will come to the lab three times: once for 1.5 hour intake session and
two times for a 3.5 hour testing session (of which 75 minutes during fNIRS-EEG
measurements). 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.
Bomenweg 4
Wageningen 6703HD
NL
Bomenweg 4
Wageningen 6703HD
NL
Listed location countries
Age
Inclusion criteria
- Aged 60-75 years
- Right-handed
- Dutch speaking
- Normal or corrected to normal vision
Exclusion criteria
- Mini-Mental State Examination (MMSE) score of <24
- Estimated IQ of <85 (based on Nederlandse Leestest voor Volwassenen (NLV) -score)
- Hospital Anxiety and Depression Scale score of >11
- Current or past psychiatric disorder, such as psychosis or major depression
- Current or past neurological disorder, such as severe cerebral vascular disease (e.g. cortical stroke, subarachnoid hemorrhage), Parkinson*s disease, epilepsy, traumatic brain injury, central nervous system infection, brain tumor, and alcoholic encephalopathy. N.B. Transient Ischaemic Attack, lacunar infarction and white matter lesions are no exclusion criteria.
- Current severe systemic disease such as coronary artery disease, myocardial infarction < 6 months, heart failure (unstable), chronic obstructive pulmonary disease (unstable)
- Current endocrine or metabolic disorders such as hepatic or renal problems
- First degree family history of schizophrenia, bipolar disorder or major depressive disorder
- Thyroid problems, such as hyperthyroidism, subclinical hyperthyroidism (TSH <0.4 mU/L), 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
- Use of tyrosine supplements within one month prior to visit
- Being allergic or having a dislike to the product carrier (banana-flavored yoghurt)
- Blood pressure < 90/60 mmHg or > 160/90 mmHg (use of antihypertensives are allowed)
- General medical conditions, such as repetitive strain injury (RSI), colorblindness or sensori-motor handicaps, which may confound the results of the study, as judged by the investigator
- Alcohol consumption of more than 14 (women) or 21 (men) units per week
- Habitual smoking, defined as more than a pack of cigarettes per week
- Current participation in another study, or a specific cognitive training study within the past six months, or a study using the same cognitive paradigm as the current study
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 | NL52264.091.15 |