Table 1.

Description of studies included in the systematic review (n = 10)

Publication	Source of data and study design (follow up)	Population (age/sex)	Dementia diagnosis	Exposure (via NOVA unless otherwise stated)	Adjustment	Outcome
Dearborn-Tomazos et al. 2019 [32]	Atherosclerosis Risk in Communities (ARIC) Prospective cohort (20 years)	15,792 males/females, mean age 54.6 years	ICD-9 and ICD-10 criteria for dementia	Western dietary pattern: Moderate: 2° tertile High: 3° tertile	Age, sex, education, race-field centre, total calories, apolipoprotein E e4 status, alcohol use, smoking, activity level, BMI, total cholesterol, coronary heart disease, hypertension, diabetes, stroke	Dementia: Moderate 1.01 (0.91–1.13) and high intake 1.06 (0.92–1.22) had no significant association
Dobreva et al. 2022 [35]	UK Biobank Retrospective cohort (11.4 years)	249,511 males/females, mean age 62	ICD-9 and ICD-10 criteria for dementia	Processed meats: Moderate: 3° quintile High: 5° quintile	Age, sex, Townsend deprivation score, age left education, household income, physical activity, smoking status, weekly alcohol units, loneliness, depression, BMI, cholesterol, diabetes, hypertension, cardiovascular events, major dietary changes	Dementia: Moderate 0.83 (0.72–0.95) and high intake 1.07 (0.88–1.30) had no significant association
Feng et al. 2020 [30]	China Health and Nutrition Survey Retrospective cohort (18 years)	8236 males/females, mean age 62.98 years	Cognitive Screening Item: Telephone Interview for Cognitive Status (< 7)	Fast-food, SSBs, salty snacks: Moderate: No data High: High intake	Age, sex, smoking, drinking, ethnicity, education levels, married status, regions, gross family income, hypertension, diabetes, death, BMI and physical activity	MCI: High intake increased the risk from 28% to over twofold Fast-foods 2.40 (1.76–3.28) SSBs 1.28 (1.02–1.61) Salty-snacks 1.52 (1.17–1.96)
Filippini et al. 2020 [36]	Newly-diagnosed patients referred to the Cognitive Neurology Network of Modena province Case–control	108 males/females, mean age 65 years	DSM-V criteria for dementia	Pizza, salty snacks, processed meats, sweets, chocolates, cakes, pastries, ice cream, SSBs: Moderate: 2° tertile High: 3° tertile	Sex, age, educational attainment, and energy intake	Dementia: Moderate and high intake had no significant association Moderate intake: Pizza and salty snacks 0.33 (0.11–0.84) Processed meats 0.51 (0.18–1.47) Sweets, chocolates, cakes etc. 1.47 (0.50–4.38) SSBs 1.67 (0.38–7.40) High intake: Pizza and salty snacks 0.33 (0.11–0.84) Processed meats 0.94 (0.35–2.54) Sweets, chocolates, cakes etc. 2.61 (0.82–8.34) SSBs 0.62 (0.18–2.18)
Fu et al. 2022 [31]	Tianjin Elderly Nutrition and Cognition Cohort (TENCC) Cross-sectional	4457 males/females, mean age 67.6 years	Petersen criteria (5 out of 5 of the criteria needed)	Processed foods dietary pattern: Moderate: 2° quartile High: 4° quartile	Sex, age, educational level, income, marital status, BMI, PA, hypertension, diabetes, hyperlipidemia, GS, smoking status, drinking status, and total energy intake	MCI: Moderate intake 1.32 (0.97–1.79) had no significant association High intake 1.39 (1.03–1.88) increased by 39%
Li et al. 2019	UK Biobank Prospective cohort (10 years)	72,083 males/females, mean age	ICD-10 criteria for dementia	Moderate: 2° quartile High: 4° quartile	Age, sex, education level, total daily intake, smoking, alcohol intake, physical activity, BMI, sleep duration, cardiovascular disease, family history of dementia, healthy diet score	Dementia: Moderate intake 1.02 (0.80–1.31) had no significant association High intake 1.44 (1.12–1.85) increased the risk by 44%
Pearson et al. 2016 [33]	REGARDS Prospective cohort (6.8 years)	18,080 males/females, mean age 64.8 years	Six-item Screener (SIS) (shifting from intact cognitive function to impaired cognitive function (a score ≤ 4))	Southern dietary pattern: Moderate: 3° quintile High: 5° quintile	Age, race, sex, region, total energy intake, income, education, physical activity, smoking status, BMI, hypertension, diabetes, cardiovascular disease and depressive symptoms	MCI: Moderate 1.07 (0.81–1.33) and high intake 1.16 (0.93–1.45) had no significant association
Ylilauri et al. 2022 [37]	Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) Prospective cohort (22 years)	2497 males, aged 42–60 years	ICD-8, ICD-9 and ICD-10 criteria for dementia	Processed red meats: Moderate: 2° quartile High: 4° quartile	Age, baseline examination year, energy intake, education years, pack-years of smoking, BMI, diabetes, leisure-time physical activity, coronary heart disease, use of lipid-lowering medication, intakes of alcohol, fibre, sum of fruits, berries and vegetables, and dietary fat quality	Dementia: Moderate 1.06 (0.79–1.44) and high intake 1.12 (0.79–1.57) had no significant association
Zhang et al. 2021 [38]	UK Biobank Retrospective cohort (8 years)	493,888 males/females, mean age 56.5 years	ICD-9 and ICD-10 criteria for dementia	Processed meats: Moderate: 2° quartile High: 4° quartile	Age, gender, ethnicity, socioeconomic status, educational level, region, BMI, physical activity, smoking status, typical sleep duration, stroke history, family history of dementia, and dietary factors including total consumption of vegetables and fruits, total fish, tea and coffee, and alcohol	Dementia: Moderate intake 1.13 (1.02–1.25) increased the risk by 13% High intake 1.67 (1.41–1.98) increased the risk by 67%
Miao et al. 2021 [34]	Framingham Heart Study (FHS) Retrospective cohort (19 years)	2664 males/females, mean age 53.7 years	DSM-IV criteria for dementia	SSBs: Moderate: 2° tertile High: 3° tertile	Age, sex, hypertension, smoking, BMI, diabetes	Dementia: Moderate intake 1.53 (1.21–1.93) increased the risk by 53% High intake 2.80 (2.24–3.50) increased the risk over twofold

The outcome column represents the odds ratio or relative risk calculated by the authors of the original included studies

ICD International Classification of Diseases, DSM Diagnostic and Statistical Manuscript of Mental Disorders