The association of angiotensin-converting enzyme with biomarkers for Alzheimer’s disease

Table 1 Baseline characteristics for the separate study groups after imputation

	Control group (n = 40)	AD group (n = 78)
Demographics
Age (years)	63 (8)	68 (7)**
Female sex (%)	47	64*
Education (range 1 to 7)	6 (3 to 7)	5 (3 to 6)
APOE-ϵ4 carrier (%)	23	66*
MMSE (range 0 to 30)	28 (26 to 30)	22 (16 to 27)*
Vascular risk factors/disease
Smoking (% current)	23	23
Body mass index (kg/m²)	25 (5)	24 (5)
Diabetes mellitus (%)	14	14
Hypercholesterolemia (%)	28	22*
Blood pressure measures
Systolic (mmHg)	133 (14)	147 (22)**
Diastolic (mmHg)	83 (9)	86 (13)**
Hypertension (%)	30	55*
ACE measures
CSF ACE protein level (ng/ml)	3.78 (1.30)	3.56 (1.16)**
CSF ACE activity (RFU)	155 (61)	148 (58)*
Serum ACE protein level (ng/ml)	4.22 (1.50)	3.72 (1.14)**
Serum ACE activity (RFU)	255 (152)	205 (116)**
CSF biomarkers
Amyloid β_1–42 (pg/ml)	887 (622 to 1,157)	475 (334 to 743)**
Total tau (pg/ml)	246 (122 to 371)	619 (344 to 1,102)**
Phosphorylated tau (pg/ml)	45 (29 to 74)	87 (54 to 137)**

Data presented as mean (standard deviation), percentage, or median (10th to 90th percentile). Percentage of missing values before imputation: education, 0.8%; APOE genotyping, serum ACE protein and activity levels, 1.7%; MMSE, 3.4%; smoking, 7.6%; diabetes mellitus and hypercholesterolemia, 14%; all other variables, 0%. ACE, angiotensin-converting enzyme; AD, Alzheimer’s disease; APOE, apolipoprotein E; CSF, cerebrospinal fluid; MMSE: Mini-Mental State Examination; RFU, relative fluorescence units.*P < 0.05 versus controls, **P < 0.01 versus controls.

ISSN: 1758-9193