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Table 2 Overview of studies on dementia and risk factors in sub-Saharan Africa

From: Epidemiology of neurodegenerative diseases in sub-Saharan Africa: a systematic review

Author, year of publication

Country/setting

Design/period of study

Population characteristics

Diagnostic criteria

Incidence

Prevalence (%)

Risk factors

Lambo [58], 1966

Nigeria

Retrospective/Cross-sectional, 1954-1963

328 participants (26% ≥60 y.)

Not provided

NA

Senile dementia*:

NA

Hospital

Overall: 26%, Men: 18.9% Women: 30.5%

75 cases of dementia (21 men)

Ben-Arie [39], 1983

South Africa

Cross-sectional, 1982

139 participants aged ≥65 y.

MMSE/ICD-8 codes

NA

Any (severe) dementia 8.6% (3.6%)

NA

Community

Makanjuola [59], 1985

Nigeria

Cross-sectional 1979-1982

51 (5.2% of new consultations); age ≥60 y.

ICD-9 codes

NA

Dementia 11.2%

NA

Hospital

Gureje [60], 1989

Nigeria

Cross-sectional, 1984

1914 patients;

ICD- 9 codes

NA

No case of dementia

NA

Community

Ogunniyi [40], 1992

Nigeria

Cross-sectional

930 participants; age ≥40 y. (293 aged ≥65 y.); No case of dementia

DSM-III-R criteria

NA

No case of dementia

NA

Community

Osuntokun [61], 1994

Nigeria, hospital Autopsy study

Cross-sectional 1986- 1987

111 brains autopsied including 85 patients aged ≤60 y.

Beta A4 amyloid on brain tissues

NA

Heavy/moderate/mild plaque load: 0/6.3/18.9%

NA

Osuntokun [41], 1995

Nigeria, community

Cross-sectional

56 subjects (17 with dementia and 12 with AD); age ≥65 y.

Dementia –CSID

NA

APOE ϵ4 allele in dementia/AD/controls 17.6/16.7/20.5%.

NA

AD - NINCDS-ADRDA criteria

Osuntokun [38], 1995

Nigeria, hospital Autopsy study

Cross-sectional

198 brains were autopsied

senile plaque, neurofibrillary tangle, and amyloid vascular degeneration

NA

No evidence of NFT or senile plaque

NA

1986- 1987

Including 45 (23%) ≥65 year

Hendrie [32], 1995

Nigeria, community

Cross-sectional

2494 participants, age ≥65 y., Dementia -28, AD - 18, VaD - 8.

Dementia: CSID/DSM-III-R/ICD-10/AD: NINCDS-ADRDA criteria

NA

Dementia - Overall/65-74/75-84/≥85 y:

 

1992-1993

2.3/0 · 9/2.7/9.6;

AD - 1.4/0.5/1.7/5.9%

Indianapolis-USA, community & nursing home

Cross-sectional

2212participants, aged ≥65 y. (community) and 106 (nursing home)

Dementia: CSID/DSM-III-R/ICD-10/AD: NINCDS-ADRDA criteria

NA

Dementia Overall/65-74/75-84/≥85 y:

NA

1992 - 1993

8.2/2 · 6/11.4/32.4%

AD -6.2/1.6/8.0/28.8%

Ogeng'o [33], 1996

Tanzania, hospital

Cross-sectional

12 Non-demented subjects aged 45–83 y.

senile plaque, neurofibrillary tangle, and cerebral amyloid angiopathy

NA

Amyloid β plaques:17%

NA

1996

Autopsy study

Neurofibrillary Tangles: 17%; Cerebral Amyloid angiopathy: 17%

Kenya, hospital

Cross-sectional Autopsy study

20 Non-demented subjects aged 45–70 y.

Senile plaque, neurofibrillary tangle, and cerebral amyloid angiopathy

NA

Amyloid β plaques: 15%; Neurofibrillary Tangles: 15%; Cerebral Amyloid angiopathy: 15%

NA

USA-Cleveland, Hospital

Cross-sectional/Autopsy study

20 Non-demented subjects aged 48–84 y.

Senile plaque, neurofibrillary tangle, and cerebral amyloid angiopathy

NA

Amyloid β plaques: 20%; Neurofibrillary: 15%; Cerebral Amyloid angiopathy: 20%

NA

Ogunniyi [42], 1997

Nigeria, community

Cross-sectional

2494 participants aged >65 y screened, 28 with dementia.

Screening: CSI-D)

NA

Any/ AD/ vascular dementia - 1.1/0.7/0.3%

N A

1992-1994

Dementia: DSM-III-R and ICD-10 codes

AD: NINCDS-ADRDA

Sayi [62], 1997

Tanzania, hospital

Cross-sectional

24 demented and 286 non-demented participants aged 50–89 y.

Swahili modified MMSE

NA

Prevalence of ϵ4 allele of APOE: Demented - 25%; non demented - 21%

NA

Kenya, hospital

Cross-sectional

22 demented and 60 non-demented participants aged ≥65 y.

Swahili modified MMSE

NA

Prevalence of ϵ4 allele of APOE: Demented - 42%, non-demented - 27%

NA

Baiyewu [63], 1997

Nigeria, Nursing home

Cross-sectional

23 participants (in a nursing home) aged 66–102 y.; 11 women

DSM-III-R/AGECAT

NA

Any dementia (AD) - 47 · 8% (26 · 1%)

NA

1994

Hall [34],1998

Nigeria, community

Case–control

2494 participants; age ≥ 65 y.;

Screening: CSID

NA

18 cases of possible or probable AD1.4%

age (OR = 1.15; 95%

423 clinically assessed after screening,

CI = 1.12-1.18) and female gender (OR = 13.9; 95% CI = 3.85-50.82)

Dementia: DSM-III-R/ICD-10/AD: NINCDS-ADRDA

USA–Indianapolis, community

Case–control

2212 participants; age ≥ 65 y.;

Screening: CSID

NA

Possible/probable AD 6.2%

age, family history of dementia, education; rural residence

Dementia: DSM-III-R/ICD-10/AD: NINCDS-ADRDA

351 clinically assessed after screening,; 49 (men 17) diagnosed with AD

Uwakwe [70], 2000

Nigeria, Hospital

Cross-sectional

119 participants; age ≥65 y; 3 had dementia

Geriatric Mental State and/ICD-10

NA

2.8%

NA

1995-1996

Ogunniyi [43], 2000

Nigeria, community

Cross-sectional 1992-1994

2494 participants, age ≥65 y.; 28 with dementia (men: 8) including 18 with AD, 8 with vascular dementia

Screening: CSID

NA

Any dementia 2.3%

Age (OR: 1.15), female gender (13.9), living with others (OR: 0 · 06)

Dementia: DSM-III-R/ICD-10

AD: NINCDS-ADRDA

AD: 1.4%

E4 allele in AD (normal subjects) 34.2% (21.8%)

Indianapolis-USA, community

Cross-sectional

2212 participants, age ≥65 year; 65 with dementia including 49 with AD, 10 with vascular dementia

Screening: CSID

NA

Dementia (AD) overall/65-74/75-84/≥85 y – 8.2 (6.2)/2.62 (1.58)/ 11.4 (8.0)/32 · 4% (28.8%);

Age, rural residence, family history of dementia, education

Dementia: DSM-III-R/ICD-10

1992-1994

AD: NINCDS-ADRDA

Hendrie [35], 2001

Nigeria, community

Prospective cohort Baseline survey in 1992-1993

2459 participants included after the first visit; 1303 (men 461) completed the follow-up; age ≥65 y.

Screening: CSID

Dementia: 13.5/1,000

NA

NA

Dementia: DSM-III-R/ICD-10

AD: NINCDS-ADRDA

AD: 11.5/1000

USA-Indianapolis, community

Prospective cohort

2147 African-Americans included after the first visit; 1321 (men 417) completed the follow-up; age ≥65 y.

Screening: CSID

Dementia (AD)

NA

NA

Baseline survey in 1992-1993

Dementia: DSM-III-R/ICD-10/AD: NINCDS-ADRDA

32.4/1,000 (25.2/1,000)

Baiyewu [44], 2002

Nigeria, community

Prospective cohort baseline survey in 1992-1993

2487 participants; age ≥65 y.;

Screening: CSID

Conversion from CIND to dementia 16 · 1%; From CIND to normal 25 · 3%

NA

Sex

Dementia: DSM-III-R/ICD-10

423 clinically assessed after screening; 152 diagnosed with CIND; 28 (men 7) with dementia, 87 followed up for 2 years.

Perkins [36], 2002

Ibadan-Nigeria community

Prospective, 1992-1993

2487 participants; age ≥65 y;

Screening: CSID

NA

1.8%

Dementia associated with mortality

Dementia: DSM-III-R/ICD-10

423clinically assessed after screening

Indianapolis-USA, Community

Prospective Baseline survey in 1992-1993

2212 participants; aged ≥65 y.;

Screening: CSID

 

4.9%

Dementia associated mortality (adjusted RR: 2 · 05)

342 clinically assessed after screening

Dementia: DSM-III-R/ICD-10

Lane [37], 2003

Nigeria Community

Prospective 8.7 y follow up Baseline 1992-1993

968 participants (271 aged ≥75 y.);

Screening: CSID

NA

NA

ApoEϵ4 alleles not associated with increased mortality

23with dementia at follow-up

Dementia: DSM-III-R/ICD-10

Indianapolis-USA, Community

Prospective 9.5 y. Baseline 1992-1993

353 participants (17 4 aged ≥75 y.); 17 with dementia at follow-up

Screening: CSID

NA

NA

ApoEϵ4 associated with increased mortality for patient under 75 year

Dementia: DSM-III-R/ICD-10

Ogunniyi [45], 2005

Nigeria, Community

Cross-sectional/1992- 1998

98 demented subjects; age ≥65 y.

Screening: CSID

NA

AD: 82% of all cases

NA

Dementia: DSM-III-R/ICD-10

VaD: 11.1% of all cases

Kengne [16], 2006

Cameroon,

Cross sectional,

4041 neurologic consultations

Not provided

NA

0.4% (all neurologic admission), 19% (neurodegenerative diseases)

NA

Hospital

1993-2001

145 with neurodegenerative diseases

16 (men 14) with dementia, mean age 67.8 y.

Gureje [46], 2006

Nigeria, Community

Cross-sectional, 2003-2004

2152 participants at baseline with a respondent rate of 74% (1904 participants). Aged 65 year or older.

adapted 10-Word Delay Recall Test (10-WDRT)10

NA

Overall: 10.1%;

Female gender, Increasing age, alcohol

Female: 14.6%

Men: 7.0%

Gureje [71], 2006

Nigeria Community

Cross-sectional,

2245 DNA samples, 830 had a diagnosis

Screening: CSID

NA

Any dementia (16.9%

E4 allele in AD (normal subjects) 26 · 0% (21 · 7%)

Dementia: DSM-III-R/ICD-10

AD: 14.8%

Ogunniyi [72], 2006

Nigeria, Community

Case–control

62 participants with AD (Men 16.1%, mean age 82 y) and 461 non demented (men 33.2%, mean age 77 y)

Screening: CSID

NA

 

Age (OR 1 · 07)

Dementia: DSM-III-R/ICD-10/AD: NINCDS-ADRDA

Rural to age (OR 2 · 93) Hypertension (OR 0 · 33)

Indianapolis-USA, Community

Case–control

89 participants with AD (men 30.3%, mean age 83 y), mean age 77 y) and 381 non demented (Men 31.2%, mean age 78 y)

Screening: CSID

NA

 

Age (OR 1.09

Rural to age (OR 2.08)

Dementia: DSM-III-R/ICD-10/AD: NINCDS-ADRDA

Alcohol consumption (OR 0.49)

Uwakwe [64], 2006

Nigeria, Community

Cross-sectional

30 patients (men 12) with dementia and their caregivers (total 30)

Not provided

NA

N:52;

 

2003-2005

AD: not provided

Men: 12

Ochayi [47], 2006

Nigeria, Community

Cross-sectional 2002

280 participants; age ≥65 y.;

CSID

NA

Overall dementia: 6.4%

Female gender,

Lower body mass index, age, NSAIDS

65-74 year old: 5.2%

18 (men 2) with dementia

≥85 year 16%.

Hall [48], 2006

Nigeria, Community

Cross-sectional

1075 participants; age ≥ 70 y. 29 (men 5) with AD,

NINCDS-ADRDA

NA

NA

Total- or LDL- cholesterol in individuals without the APOE-ϵ4 allele

Uwakwe [73], 2009

Nigeria, community

Cross-sectional

914 (men 432) participants, age ≥65 y; 87 with ≥2 tests memory tests impaired

Memory impairment assessed by MMS, CISD and 10 word list immediate and delayed recall

NA

9.9%

NA

Guerchet [50], 2009

Benin Community

Cross-sectional

502 (men 156) participants, aged ≥65 y; 52 with cognitive impairment

Screening: CSI-D

NA

Cognitive impairment

Age, current depressive disorder, absence of the APOE ϵ 2

Overall: 10.4%; men 7.7 women 11.5%

Dementia: DSM-IV

AD: NINCDS-ADRDA

 

Dementia Overall: 2.5%, men 0.6% women 3.4%

13 (men 1) with dementia

Toure [67], 2009

Senegal

Cross-sectional

872 participants; age ≥55 y.

DSM-IV-R

NA

Overall 6.6%

Age, social isolation, history of stroke, epilepsy, family history of dementia, Parkinson’s disease

Hospital

2004-2005

58 cases of dementia

Napon [68], 2009

Burkina Fasso

Cross-sectional

15815 (2396) out (in) participants; age ≥15 y.; 72 (and 53 inpatients) with dementia; AD: 7; VaD: 19 cases

DSM-IV

NA

outpatients: 0.45% inpatients: 0.22%

NA

Hospital

Guerchet [49], 2010

Central African Republic Community

Cross-sectional

509 interviewed; 496 (men 218) included in final sample, age ≥65 y.

Screening: CSID

NA

Overall: 8.1%, men 2.7%, women 12.2%

NA

2008-2009

Dementia: DSM-IV

188 with cognitive impairment and 40 (men 6) with dementia (mean age 76 y.); 33 (men 3) with AD and 7 (men 2) with VaD

AD: NINCDS-ADRDA Hachinski scale,

Republic of Congo Community

Cross-sectional

546 interviewed; 520 (men 198) included in final sample, age ≥65 y.

148 with cognitive impairment and 35 (men 9) with dementia (mean age 79 y.); 24 (men 7) with AD and 11 (men 3) with VaD

CSID/ DSM-IV and NINCDS-ADRDA Hachinski scale

 

Overall: 6.7%, men 4.5%, women 8.1%

NA

2008-2009

Chen [65], 2010

Kenya

Cross-sectional

100 participants; age ≥ 65 y.

CSI-D using a version in Kikuyu.

NA

Apo ϵ4 allele frequency:

NA

Hospital

Demented 31.3%, non-demented 32.2%

84 controls (men 38) and 16 with dementia participants (men 7)

Ekenze [21], 2010

Nigeria

Cross-sectional

8440 admissions; 1249 (men 640) with neurological diseases (age range18-83 y.); 38 (men 23) with dementia

Not specified

NA

3%

NA

Hospital

2003-2007

Siddiqi [69], 2009

Zambia

Cross-sectional

443 inpatients (men 219); median age 39 y., 67 with HIV; 368 outpatients (men 168); median age 39 y., 58 with HIV; 36 with dementia

Not specified

NA

Dementia:

Dementia in HIV + patients 8 (13.8%) vs. general population 9 (2.9%) (p = 0.002)

Overall: 4.4%

Hospital

2006

Yusuf [74], 2011

Nigeria Community

Cross-sectional

322 participants (men 128); mean age: 75.5 y

Screening: CSID/CERAD/SDT

NA

Dementia: 2.8%

Age

AD: 1.9%

VaD: 0.6%

Dementia: DSM-IV and ICD-10

9 cases of dementia (men 3); mean age: 82.4 y

LBD: McKhan clinical criteria

FTD: McKeith clinical criteria

Gureje [51], 2011

Nigeria, Community

Prospective Cohort Baseline 2003-2004

2,149 participants at baseline

10-Word Delayed Recall

21.80/1,000

NA

Poor social engagement, rural residence, low economic status, female gender, age.

Test (cut off of 18)

1,408 at 39 months follow-up; 85 (among ≥65 y.) developed dementia

Ogunniyi [52], 2011

Nigeria Community

Cohort study

1559 participants aged > 65 year without dementia a baseline. 136 (men 33) with dementia (mean age 83.1 y.) at follow-up; 255 with MCI

Dementia: DSM-III-R and ICD-10

Dementia: 8.72/1,000/year

NA

Low BMI

1992-2007

MCI: 16.35/1000/year

Ogunniy [53], 2011

Nigeria Community

prospective cohort baseline 1992

2718 participants interviewed

Dementia: DSM-III-R and ICD-10

Dementia/AD/VaD (per 1,000/year) 11.50/9.50/1.10

NA

Higher SBP, DBP and PP

1753 (age ≥65 y.) in the final sample

120 (men 30) with dementia (mean age 83.8 y.); 99 with AD; 11 with VaD

Paraïso [56],

Benin Community

Cross-sectional

1,139 (men 523) participants; age ≥65 y.; 42 (men 13) with dementia (mean age 79 · 1 y)

Screening: CSI-D

NA

Dementia Overall 3.7% men 1.1% women: 2.5%

NA

2011

2008

Dementia: DSM-IV

32 with AD, 105 with CIND

AD: NINCDS-ADRDA

 

AD Overall 2.8%

VD Overall 0.8%

VaD: NINCDS-AIREN

Amoo [30],

Nigeria

Cross-sectional

240,294 participants

Dementia: ICD-10

NA

Dementia: 45/100,000

NA

2011

AD; 25 · 8/100,000

Hospital

1998-2007

VaD: 7 · 4/100,000

108 (men 51) with dementia (mean age: 70.1); 62 (men 24) with AD; 18 (men 13) with VaD; 4 (men 2) with mixed forms;

ADNINCDS – ADRDA

VaD: NINCDS –AIRENS

LBD: McKeith criteria,

FTD: Lund and Manchester Criteria

4 (men 2) with FTD; 3 (men 0) with DLB; 13 (men 2) with unclassified dementia

Ndiaye [31], 2011

Senegal

Cross-sectional

132 patients seen at a memory clinic (men 41, mean age: 67 y

Screening: “Test du Senegal”/modified HodKinson test

NA

MCI: 14.4%

NA

Hospital

2004-2005

57 with dementia; 37 with AD, 10 with VaD, 5 with FTD and 1 with LBD.

Dementia: 43.2%

AD: 64.7% of all cases of dementia

MCI: Petersen criteria

Dementia: DSM-IV

Coume [75], 2012

Senegal

Cross-sectional

872 (men 546) participants aged >55 y; mean age 67 · 2 y

Test du Senegal

NA

Cognitive impairment 10.8%

NA

Hospital

2004-2005

94 (men 65) with cognitive impairment (74 aged > =65 y)

Baiyewu [54]., 2012

Nigeria

Cross-sectional/2001 and 2004

21 (men 4) participants with normal cognition (mean age 82.8 y.)

Screening: CSID

NA

NA

NA

Dementia: DSM-III-R/ICD-10

Community

53 (men 4) with cognitive impairment (mean age 80.9); 34 (men 6) with dementia (mean age 83.3 y)

AD: NINCDS-ADRDA

Toure [66], 2012

Senegal

Cross-sectional

507 participants; age ≥65 y.

Screening: Aging in Senegal Questionnaire

NA

8.9%

advanced age (Age ≥80 y, OR 4.3, 95% CI 1.4-13), illiteracy, epilepsy, family history of dementia

45 with dementia

DSM-IV-R

Hospital

2004-2005

Longdon [57], 2012

Tanzania

Cross-sectional

1198 (men 525) participants; age ≥70 y; 78 with dementia

Screening: CSI-D

NA

6.4%

Advanced age

Community

2010

DSM-IV-R

Onwuekwe [76], 2012

Nigeria

Cross-sectional

135 participants (men: 79), aged between 16–76 y

MMSE (cut off of 17 for MCI)

NA

MCI: 5.9%

 

Hospital

2004

8 with MCI

Guerchet [55], 2012

Central African Republic, Congo

Cross-sectional

509 interviewed; 496 (men 218) included in final sample; age ≥65 y.; 188 with cognitive impairment

Dementia: DSM-IV-R/AD: NINCDS-ADRDA

NA

Dementia: 7.4%

Hypertension, low BMI, depressive symptoms, change of residence, age (OR 2.59, 95% CI, early death of one parent, female gender

2008-2009

Community

AD: 5.6%

546 interviewed; 520 (men 198) included in final sample; age ≥65 y.; 148 with cognitive impairment

   

Overall 75 (men 15) had dementia 18 with vascular dementia

    
  1. AD: Alzheimer’s disease; APOE: Apolipoprotein E; ICD: International Classification of Disease; BMI: Body Mass Index; CI: confidence Interval; CIND: Cognitive Impairment and No Dementia; CSID: Community Screening Interview for Dementia; DSM-III-R: Diagnostic and Statistical Manual 3rd edition revised; MMSE: Mini Mental State Examination; NA: Not available; NFT: Neurofibrillary tangle; NINCDS/ADRDA: National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association; OR: Odd ratio; SCEB: short cognitive evaluation battery; USA: United States of America; VaD: Vascular dementia; y: years.