| Study | Study population | Study design | Cognitive assessment | Results | Comment |
| Budge et al., 2002 [5] | 158 community dwelling people age 60 - 91 yr | Cross section of prospective cohort | CMCOG, MMSE, GDS | Higher tHcy levels associated with lower memory scores per umol/L (OR 1.15, 95% CI 1.10 - 1.27) | OR adjusted for age, sex, serum cystatin C level and systolic blood pressure |
| Duthie et al., 2002 [6] | 334 community dwelling people who had participated in Scottish Mental Survey of 1932 and 1947 | Cross section | MMSE,NART, RPM, AVLT, WAIS | tHcy levels negatively associated with scores on RPM, WAIS in older cohort with higher tHcy levels (mean 10.9 umol/l, 95% CI 10.1 - 11.5) | Results adjusted for childhood intelligence quotient |
| Pins et al., 2002 [7] | 1077 people aged 60 - 90 yr in Rotterdam Scan Study | Cross section of prospective cohort | Abbreviated Stroop tesatl Letter-Digit Substitution Task, Verbal fluency test, PPMST, Modified Rey’s test | Patients with tHcy > 14 umol/l had lower scores for global cognitive function (diference-0.20, 95%CI-0.30 - 0.11) | Results adjusted for age, sex, education level, depression, serum creatinine level |
| Miller et al., 2003 [8] | 1789 community dwelling people aged > 60 yr in Sacramento Area Latino Study on Aging | Cross section of prospective cohort | 3MSE, verbal and visual memory tests, object naming conceptualization and attention span tests | Inverse relation between tHcy levels and scores on 3MSE (p = 0.02), picture association (p = 0.05), verbal attention span (p = 0.04), and recognition tests (p = 0.001), | Multiple linear regression model included folate, cobalamin, age creatinine, sex, education and acculturation |
| Ravaglia et al., 2003 [9] | 650 community dwelling people aged 65 - 91 yr (mean 73 yr) with normal cognitive function in Conselice Study | Population based study | MMSE | Inverse relation between odds of tHcy level > 15 umol/l and MMSE scores | Results adjusted for age, income, education level, serum creatinine level, serum vitamin B index, active lifestyle, coffee and meat consumption |
| Garcia et al., 2004 [10] | 281 community dwelling people aged >65 yr | Cross section | Stroop, Mattis DRS, CVLT | Subjects with elevated tHcy levels (>13.9 umol/l) had lower stroop scores than those with normal tHcy levels in univariate analysis (p < 0.05) | Strongest association found between methylcitric acid and cognitive scores |
| Dufouil et al., 2003 [11] | 1241 people aged >60 yr in Epidemiology of Vascular Aging Study | prospective cohort; 4-yr follow-up | MMSE, Trail Making Test Part B, Digit Symbol Substitution Test from the WAIS, Finger Tapping Test | Odds of cognitive decline 2.8 (95% CI 1.2 - 6.2) in patients with tHcy level > 15 umol/l | OR adjusted for age, sex, education level, baseline cognition, BMI, alcohol consumption, smoking, hypertension, hypercholesterolemia, Glycemix status, history of vascular disease, and folate and B12 levels |
| Kalmijn et al., 1999 [12] | 702 community dwelling people aged > 55 yr in Rotterdam Study | prospective cohort; mean follow-up 2.7 yr | MMSE | No association between tHcy and cognitive impairment (highest v. lowest tertile, OR 0.91, 95% CI 0.52 - 1.58) | OR adjusted for age, education level, and baseline MMSE score |
| Ravaglia et al., 2000 [13] | 54 people aged > 65 yr in Conselice Study | Cross section of prospective cohort | MMSE, clock drawing test, prose memory test, Corsi block tapping task, Mental Deterioration Battery | No association between tHcy and cognitive test scores | Results adjusted for age, sex, education level, smoking status, alcohol or coffee consumption, and previous cardiovascular disease |