an emerging nutrient in brain function, Biofactors

Dependent variables: subjective memory complaint
The SMC was rated using the Memory Complaint Questionnaire
(MAC-Q) [14], in the absence of delirium identified with the
Confusion Assessment Method [15]. The six-item MAC-Q requires
participants to compare current memory function to memory function
at earlier ages in daily scenarios. Five questions address daily
activities compared to 5 years ago; and one final question addresses
the general feeling on overall memory function compared to 10
years ago. For each question, five possible answers range from
“much better now” (scored 5)to “much worse now” (scored 1), with
a total score out of 30 (best). Serious SMC was defined as MAC-Q
score ≤15 (/30), as previously published [12]. The MAC-Q is easy
to perform, has been validated against lengthy questionnaires, and
demonstrates good internal consistency together with satisfactory
test-retest reliability [14].
2.4. Covariables
Age, gender, body mass index (BMI), education level, number
of comorbidities, history of stroke, objective cognitive disorders,
functional autonomy, mood, serum concentrations of vitamin
B12, thyroid-stimulating hormone (TSH), albumin, and estimated
glomerular filtration rate (i.e., creatinine clearance, eGFR) were
used as potential confounders. The BMI was calculated as: [weight
(kg)/height2(m2)]. Weight was measured with a beam balance
scale, and height with a height gauge. Evaluation of education level
was based on self-report. High education level was defined as graduate
studies. Evaluation of comorbidities (i.e., diseases lasting at
least 3 months and running a course with minimal change, whatever
the etiology) was based on self-report and medical record [16].
History of stroke was sought by questioning the patients,the family
physicians and the patients’ files. Stroke was defined according to
theWorldHealth Organizationcriteria as rapidly developed signs of
focal or global disturbance of cerebral function lasting longer than
24 h, with no apparent nonvascular cause [17]. In case of clinical
suspicion, computed tomography or magnetic resonance imaging
scan was necessary to confirm the diagnosis and to distinguish
among ischemic stroke and intracranial hemorrhage. Objective
cognitive disorders were defined as Mini-Mental State Examination
score <24 in the absence of delirium [18]. Functional autonomy
was assessed with the 4-item Instrumental Activities of Daily Living
(IADL) score (range 0–4, worst) [19]. Mood was rated with the
4-item Geriatric Depression Scale (GDS) score (range 0–4, worst)
[20]. Finally,the serumconcentrations of vitaminB12, TSH, albumin
and creatinine were measured using automated standard laboratory
methods at the University Hospital of Angers, France, and
eGFR was calculated using the Cockcroft-Gault formula ([(140–age
years) × weight kg/creatinine mol/L] × 1.04 for females, and ×1.25
for males).