Table 2.

Trace elements levels (µg/g) in hair samples of the study participants, reported as mean ± standard deviation (SD) and (range) according to the cognitive status (HS = healthy subjects; SMC = subjective memory complaints; MCI = mild cognitive impairment; DEM = Dementia). Also present are hair reference value ranges for non-exposed people reported from Skalny et al. [77] and Mikulewicz et al. [78].

Element	HS	SMC	MCI	DEM	Kruskal-Wallis		Pairwise Comparisons (a) (p-Value)						Hair Reference Values *
µg/g	n = 10	n = 14	n = 16	n = 39	H(3)	p-Value	DEM vs. HS	DEM vs. SMC	DEM vs. MCI	HS vs. SMC	HS vs. MCI	SMC vs. MCI
Al	6.67 ± 10.69	4.18 ± 3.36	3.80 ± 3.95	6.26 ± 8.76	1.222	0.748	N/A	N/A	N/A	N/A	N/A	N/A	2.91–11.63
	(0.23–35.96)	(0.16–11.70)	(0.78–14.02)	(0.51–49.08)
Mn	0.19 ± 0.17	0.18 ± 0.24	0.85±1.38	1.39 ± 2.83	7.089	0.069	N/A	N/A	N/A	N/A	N/A	N/A	0.002–0.91
	(0.04–0.54)	(0.05–0.87)	(0.03–5.46)	(0.03–16.10)
Fe	16.37 ± 12.24	10.79 ± 7.75	12.67 ± 9.65	18.47 ± 40.24	2.266	0.519	N/A	N/A	N/A	N/A	N/A	N/A	3.66–36.8
	(0.59–43.77)	(0.59–27.78)	(3.60–40.47)	(3.41–259.26)
Cu	10.57 ± 10.24	10.77 ± 5.82	9.85 ± 2.54	17.99 ± 36.71	1.581	0.664	N/A	N/A	N/A	N/A	N/A	N/A	7.2–82.7
	(1.62–37.10)	(0.56–22.20)	(3.83–13.39)	(2.66–237.40)
Zn	140.29 ± 65.66	118.17 ± 58.33	151.69 ± 28.64	258.10 ± 519.33	11.723	0.008 **	n.s.	0.006 **	n.s.	n.s.	n.s.	n.s.	30–327
	(10.70–234.86)	(3.99–229.00)	(103.00–200.38)	(63.25–3396.26)
Hg	0.88 ± 0.92	1.48 ± 1.40	1.63 ± 1.18	4.43 ± 13.86	17.772	<0.001 **	0.001**	n.s.	n.s.	n.s.	n.s.	n.s.	0.17–1.19
	(0.12–3.24)	(0.11–5.38)	(0.63–5.13)	(0.06–88.46)
Pb	0.29 ± 0.39	0.46 ± 0.56	0.33 ± 0.42	1.02 ± 2.11	8.839	0.077	N/A	N/A	N/A	N/A	N/A	N/A	0.19–1.39
	(0.048–1.33)	(0.001–2.20)	(0.03–1.58)	(0.03–12.75)

^a Post hoc analysis using Bonferroni method; N/A: not applicable; n.s.: not significant; * (p < 0.05); ** (p < 0.01).