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. 2021 May 25;92(11):1215–1221. doi: 10.1136/jnnp-2020-325620

Table 1.

Participant characteristics

All participants N=420
β-amyloid-positive β-amyloid-negative
N 460 77 343
Sex, % female 49 44 51
Age at assessment, mean (SD) (range) 70.7 (0.70) (69.2 to 71.8) 70.6 (0.7) (69.4 to 71.8) 70.6 (0.7) (69.2 to 71.8)
MMSE, mean (SD) (range)* 29.3 (0.89) (26 to 30) 29.1 (1.0) (26 to 30) 29.3 (0.9) (26 to 30)
PACC, z-score, mean (SD) (range)* −0.05 (0.68) (−2.43 to 1.72) −0.10 (0.73) (−2.10 to 1.31) 0.08 (0.66) (-2.43 to 1.72)
Highest education qualification, %
 None 16.2 16.9 16.1
 Below O-levels (vocational) 5.0 6.5 4.3
 O-levels or equivalent 24.8 24.7 25.5
 A-levels or equivalent 36.3 33.8 36.5
 Degree or equivalent 17.8 18.2 17.9
Childhood cognitive ability mean (SD) (range)† 0.39 (0.74) (−1.60 to 2.50) 0.41 (0.74) (−1.59 to 2.47) 0.44 (0.74) (−1.37 to 2.50)
Adult socioeconomic position, %
 Unskilled 1.0 1.3 0.6
 Partially unskilled 4.8 3.9 5.4
 Skilled manual 9.6 9.1 9.3
 Skilled non-manual 21.5 16.9 22.0
 Intermediate 52.0 53.3 51.9
 Professional 11.3 15.6 10.5
APOE status, % ε4-carrier‡§ 30.1 59.7 23.2
SCD questions
 Perceive memory or cognitive difficulties (% yes) 44.8 49.4 45.2
 Perceive decline in cognition or memory over past 2 years (% yes) 45.4 50.6 45.5
 Difficulties or decline worse than peers (% yes) 8.8¶  12.8** 8.2††
 Would seek medical advice (% yes) 2.3¶  6.4** 1.5††
 SCD age onset, mean (SD) (range) 63.2 (10.3) (20 to 70) ¶ 63.6 (10.2) (20 to 70)** 62.9 (10.7) (20 to 70)††
 SCD ≥60 years, % 93.0 90.9 93.3
Total MyCog score (out of 24): mean (SD) (range)* 4.4 (3.9) (0 to 23) 5.2 (3.6) (0 to 15) 4.3 (3.9) (0 to 23)
AD8, mean (SD) (range)‡‡ 0.2 (0.6) (0 to 5) 0.4 (1.0) (0 to 5) 0.1 (0.4) (0 to 3)
AD8, % AD8 ≥2* 4.1 10.4 2.6
Trait anxiety, mean (SD) (range) 31.8 (7.9) (20 to 65) 31.1 (8.0) (20 to 65) 31.9 (7.8) (20 to 64)
State anxiety, mean (SD) (range) 29.6 (7.9) (20 to 61) 29.3 (7.1) (20 to 52) 29.8 (8.1) (20 to 61)
Mental health disorder prevalence at age 69, % yes§§ 7.0 10.4 6.2
Family history of dementia, % yes* ¶¶ 23.9 33.8 22.5

*The difference between the amyloid groups for this variable was significant at p<0.05.

†Z-scores for childhood cognitive ability were based on the full National Survey of Health and Development cohort of n=5362, so the mean for Insight 46 participants indicates that they had higher childhood cognitive ability on average than their peers not recruited to this substudy.

‡The difference between the amyloid groups for this variable was significant at p<0.01.

§n=458 (the participants that had APOE status information available).

¶n=260 (the participants who answered ‘yes’ either to perceiving memory or cognitive difficulties or decline in cognition or memory in the last 2 years).

**n=47 (the participants who answered ‘yes’ either to perceiving memory or cognitive difficulties or decline in cognition or memory in the last 2 years).

††n=195 (the participants who answered ‘yes’ either to perceiving memory or cognitive difficulties or decline in memory or cognition in the last 2 years).

‡‡n=459 (one informant questionnaire was not completed).

§§n=452 (the participants that completed the GHQ-28 questionnaire).

¶¶Of these participants with a family history, their affected relatives were: mother=70.0%, mean age at onset (SD): 82.2 (9.1) years; father=28.2%, 78.5 (8.8) years; siblings=8.2%, 75.5 (10.0) years (percentages do not add up to 100% as some people had multiple relatives with a family history of dementia).

GHQ, General Health Questionnaire; MMSE, Mini Mental State Examination; PACC, Preclinical Alzheimer Cognitive Composite; SCD, subjective cognitive decline.