Serum NfL and GFAP levels and their association with anxiety-depression in Alzheimer’s disease patients: A clinical retrospective study

Table 1 Baseline characteristics of study subjects, n (%)/mean ± SD

Characteristics	Total (n = 270)	AD-Control (n = 148)	AD-AnxDep (n = 122)
Age (years)	73.1 ± 8.3	72.3 ± 8.0	74.1 ± 8.7
Male gender	125 (46.3)	70 (47.3)	55 (45.1)
Education (years)	9.8 ± 3.6	10.2 ± 3.8	9.3 ± 3.4
Disease duration (years)	2.8 ± 1.4	2.6 ± 1.3	3.1 ± 1.5
MMSE score	18.5 ± 4.2	19.5 ± 4.1	17.3 ± 4.2
CDR score	1.2 ± 0.5	1.1 ± 0.4	1.4 ± 0.5
Hypertension	156 (57.8)	82 (55.4)	74 (60.7)
Diabetes mellitus	89 (33.0)	46 (31.1)	43 (35.2)
Hyperlipidemia	112 (41.5)	58 (39.2)	54 (44.3)
NfL (pg/mL)	26.7 ± 9.4	21.6 ± 6.4	32.8 ± 8.6
GFAP (pg/mL)	155.6 ± 47.2	127.8 ± 34.8	187.2 ± 43.2

AD-AnxDep: Alzheimer’s disease patients with coexisting anxiety-depression; AD-control: Alzheimer’s disease patients without coexisting anxiety-depression; MMSE: Mini-Mental State Examination; CDR: Clinical dementia rating; NfL: Neurofilament light chain; GFAP: Glial fibrillary acidic protein.

Table 2 Correlation between biomarker levels and Hospital Anxiety and Depression Scale scores

Biomarker	HADS-A (r)	P value	HADS-D (r)	P value	HADS-total (r)
NfL (pg/mL)	0.448	< 0.001	0.562	< 0.001	0.516
GFAP (pg/mL)	0.422	< 0.001	0.528	< 0.001	0.492
Age	0.186	0.002	0.198	0.001	0.194
MMSE score	-0.312	< 0.001	-0.346	< 0.001	-0.332
CDR score	0.298	< 0.001	0.324	< 0.001	0.314
Disease duration	0.224	< 0.001	0.256	< 0.001	0.242

HADS: Hospital Anxiety and Depression Scale; HADS-A: Hospital Anxiety and Depression Scale-Anxiety subscale; HADS-D: Hospital Anxiety and Depression Scale-Depression subscale; NfL: Neurofilament light chain; GFAP: Glial fibrillary acidic protein; MMSE: Mini-Mental State Examination; CDR: Clinical dementia rating; r: Spearman correlation coefficient.

Table 3 Univariate analysis of risk factors for anxiety and depression

Risk factor	Odds ratio (95%CI)	P value
Age ≥ 75 years	1.88 (0.98-3.62)	0.058
Female gender	1.64 (0.88-3.06)	0.119
Education ≤ 9 years	1.86 (0.96-3.60)	0.066
Disease duration > 3 years	1.74 (0.92-3.30)	0.089
MMSE ≤ 18	2.28 (1.22-4.28)	0.010
CDR ≥ 1.5	2.04 (1.06-3.92)	0.033
Hypertension	1.24 (0.68-2.26)	0.481
Diabetes mellitus	1.20 (0.66-2.18)	0.548
Elevated NfL (> 25 pg/mL)	3.28 (1.64-6.56)	0.001
Elevated GFAP (> 150 pg/mL)	2.94 (1.50-5.76)	0.002

CI: Confidence interval; MMSE: Mini-Mental State Examination; CDR: Clinical dementia rating; NfL: Neurofilament light chain; GFAP: Glial fibrillary acidic protein.

Table 4 Risk stratification based on number of elevated biomarkers, mean ± SD

Number of elevated biomarkers	n	Anxiety-depression incidence (%)	Mean HADS	OR (95%CI)	P value
0 (low risk)	58	13.8	6.2 ± 2.8	Reference	-
1 (intermediate risk)	130	36.9	11.8 ± 4.6	3.42 (1.38-8.48)	0.008
2 (high risk)	82	76.2	18.4 ± 5.2	19.58 (7.32-52.34)	< 0.001
P for trend	-	-	-	-	< 0.001

Elevated biomarkers defined as: Neurofilament light chain > 25 pg/mL, glial fibrillary acidic protein > 150 pg/mL. HADS: Hospital Anxiety and Depression Scale; OR: Odds ratio; CI: Confidence interval.

Table 5 Sensitivity analysis and subgroup analysis

Analysis type	Subgroup	AUC (95%CI)	Sensitivity/specificity
Primary analysis	Overall (n = 270)	0.882 (0.836-0.928)	81.1%/84.5%
Stricter criteria	HADS ≥ 10	0.868 (0.818-0.918)	79.6%/83.2%
Gender-stratified	Male (n = 125)	0.876 (0.814-0.938)	80.0%/84.3%
Gender-stratified	Female (n = 145)	0.886 (0.834-0.938)	82.1%/84.7%
Cognitive severity	Moderate (MMSE 10-18)	0.902 (0.858-0.946)	83.8%/86.2%
Cognitive severity	Mild (MMSE 19-26)	0.848 (0.786-0.910)	77.4%/81.9%
Education-stratified	Low education (≤ 9 years)	0.874 (0.822-0.926)	79.8%/83.6%
Education-stratified	High education (> 9 years)	0.888 (0.836-0.940)	82.4%/85.2%
Disease duration	Early stage (≤ 3 years)	0.876 (0.820-0.932)	80.3%/83.8%
Disease duration	Later stage (> 3 years)	0.890 (0.832-0.948)	81.9%/85.1%

AUC: Area under curve; CI: Confidence interval; HADS: Hospital Anxiety and Depression Scale; MMSE: Mini-Mental State Examination.