| 
      EAAS: electrothermal atomic absorption spectrometry; EDX: energy-dispersive
    X-ray spectroscopy; NAA: neutron activation analysis; ICP-MS: inductively coupled
    plasma source mass spectrometry; LMMS: laser microprobe mass spectrometry;
    ICP-AES: inductively coupled plasma atomic emission spectrometry; INAA:
    instrumental neutron activation analysis; IF-CLM: immunofluorescence using
    confocal laser microscopy; HS: histological staining.
        | Authors | Year | Reference | Methods | Number of subjects |  
        | AD | Control |  
        | Crapper et al. | 1973 | [16] | EAAS | 5 | 3 |  
        | Crapper et al. | 1976 | [17] | EAAS | 10 | 7 |  
        | Trapp et al. | 1978 | [97] | EAAS | 4 | 4 |  
        | Crapper et al. | 1980 | [18] | EAAS | 18 | 17 |  
        | Perl and Brody | 1980 | [98] | EDX | 3 | 3 |  
        | Traub et al. | 1981 | [99] | EAAS | 7 | 26 |  
        | Markesbery et al. | 1981 | [69] | NAA | 12 | 28 |  
        | Ward and Mason | 1987 | [100] | NAA | 28 | 30 |  
        | Lukiw et al. | 1992 | [101] | EAAS | 21 | 17 |  
        | Xu et al. | 1992 | [102] | EAAS | 10 | 10 |  
        | Corrigan et al. | 1993 | [103] | ICP-MS | 12 | 12 |  
        | Lovell et al. | 1993 | [104] | LMMS | 7 | 5 |  
        | Andrasi et al. | 1995 | [105] | ICP-AES, INAA | 9 | 20 |  
        | Bouras et al. | 1997 | [106] | LMMS | 4 | 3 |  
        | Solomon et al. | 2001 | [107] | IF-CLM | 5 | 5 |  
        | Srivastava and Jain | 2002 | [108] | ICP-MS | 4 | 4 |  
        | Andrási et al. | 2005 | [109] | ICP-AES, INAA | 3 | 3 |  
        | Walton | 2006 | [110] | HS | 6 | 6 |  
        | Walton | 2010 | [111] | HS | 5 | 5 |  
        | Rushina et al. | 2011 | [112] | EAAS | 29 | 27 |  |