de Jager 2012.

Methods	2‐arm, placebo‐controlled, parallel group, randomised clinical trial, intervention for 2 years (trial short name = VITACOG)
Participants	Location: Oxford, United Kingdom. Single centre Setting of recruitment and treatment: University of Oxford Sample size: Number randomised: 138 in intervention, 133 in comparison Number completed: 110 in intervention, 113 in comparison Participant baseline characteristics: Age in years (mean ± SD) : vitamin B: 76.8 ± 5.1, placebo: 76.7 ± 4.8 Female sex : vitamin B: 70 (63.6%), placebo: 73 (64.6%) Inclusion criteria: Age >= 70 years Study partner available as informant MCI. No distinction between amnestic and non‐amnestic MCI. Screened with TICSm (≥ 17 and ≤ 29) and a category fluency test. Also MMSE ≥ 24/30, a subjective memory complaint with corroboration from a study partner using questions from the Cambridge Examination for Mental Disorders of the Elderly (CAMDEX) and normal activities of daily living using five questions from the Cambridge Behavioural Inventory. Exclusion criteria: A diagnosis of dementia or being treated with anti‐dementia drugs Active cancer Major stroke within past 3 months Treatment with methotrexate Anti‐cancer or anti‐epileptic drugs Taking folic acid > 300 mg/d, B6 >3 mg/d or vitamin B12 > 1.5 mg/d by mouth or any dose by injection
Interventions	Intervention: The B‐vitamin group received TrioBe PlusW containing 0.8 mg folic acid, 0.5 mg vitamin B12 and 20 mg vitamin B6 once daily. Comparator: Vitamin‐free tablets of similar appearance.
Outcomes	Outcomes of interest in the review: Overall cognitive functioning: MMSE, (also measured: TICSm) Specific cognitive functioning subdomain: episodic memory: HVLT‐R (Hopkins Verbal Learning Test ‐ Revised with delayed recall) Specific cognitive functioning subdomain: executive functioning: CLOX, (also measured: category fluency) Clinical global impression: global CDR Functional performance: IQCODE Total adverse events Mortality Biomarker: rate of brain atrophy on volumetric MRI
Source of Funding	Charles Wolfson Charitable Trust, Medical Research Council, Alzheimer’s Research Trust, Henry Smith Charity, Thames Valley Dementias and Neurodegenerative Diseases Research Network of the UK National Institute for Health Research, John Coates Charitable Trust, and the Sidney and Elizabeth Corob Charitable Trust. Recip AB donated vitamins, Axis‐Shield provided assay equipment for homocysteine
Declaration of Interest	"AD Smith is named as an inventor on three patents held by the University of Oxford on the use of folic acid to treat AD or MCI (US6008221; US6127370; PCT/GB2010/051557); under the University’s rules, he could benefit financially if the patent is exploited. Drs Refsum and Smith report having in the past received speaking honoraria from Recip AB, the company that donated the vitamin tablets, and from Axis‐Shield, who make the equipment used to assay homocysteine."
Notes	VITACOG study, ISRCTN 94410159, Eudract Number: 2004‐001527‐38 ISRCTN trial register entry refers to: Primary outcome measures: Rate of shrinkage of whole brain and/or brain regions assessed by volumetric MRI Changes in performance on a variety of cognitive tests Secondary outcome measures: Trial recruitment procedures Conversion to dementia Protocol refers to: Primary efficacy endpoints: Clinical: rate of shrinkage of brain assessed by volumetric MRI, change in memory test score. Secondary efficacy endpoints: Diagnosis of dementia by DSM‐IV, IQCODE, change in any of the cognitive test scores. Cognitive tests further defined as MMSE, HVLT, paired associates learning (PAL), CLOX, Trailmaking, category fluency, SDMT, Map search/attention task, TICSm. Safety and other endpoints: Included adverse events, mortality, dropout rates, compliance. Protocol also stated that EQ‐5D (quality of life) and Geriatric Depression Scale will be administered at baseline and 24 months.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Centralized telephone randomization by independent statisticians was used with full allocation concealment and minimization for age, gender, baseline TICS‐M score and consent for MRI." Comment: Appropriately randomised.
Allocation concealment (selection bias)	Low risk	Quote: "Centralized telephone randomization by independent statisticians was used with full allocation concealment and minimization for age, gender, baseline TICS‐M score and consent for MRI." Comment: Appropriate allocation concealment.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quote: "Participants, study partners, and those assessing outcomes were blind to the assignment of intervention". "The placebo group received vitamin‐free tablets of similar appearance". Comment: Measures taken to blind participants and personnel.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "Participants, study partners, and those assessing outcomes were blind to the assignment of intervention". Comment: Blinded outcome assessment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "Of the 266 participants starting the intervention, 223 participants (83.8%) completed the second visit 2 years later". Total withdrawals of 20 participants (15%) from placebo group and 23 participants (17.3%) from active treatment group. "Fewer clinical measures at follow‐up (n = 191) compared with cognitive measures (n = 223) due to some study partners being unavailable to complete the CDR and IQCODE". Comment: Loss to follow‐up < 20% over 24 months and well balanced between groups.
Selective reporting (reporting bias)	High risk	Cognitive results reported were a subgroup of those specified in the protocol, considered by the authors to be "representative of particular cognitive domains important in MCI." Diagnosis of dementia by DSM‐IV and EQ‐5D (quality of life) not reported. Cognitive results were reported by subgroups of participants with high or low tHcy rather than as an overall effect; not specified in analysis plan in published protocol (journals.plos.org/plosone/article?id=10.1371/journal/pone.0012244#s5).
Other bias	Low risk	No other risks identified.