Table 2.
Literature review results for qEEG biomarkers in humans.
| Reference | Year | Measure | Subjects | Control | Pre-HD | HD | Electrophysiological Finding(s) | Clinical correlation(s) | CAG-repeat correlation | Other |
|---|---|---|---|---|---|---|---|---|---|---|
| Lazar et al. (41) | 2015 | EEG-PSG | 82 | 36 | 38 | 8 | 5–7 Hz range (theta and alpha–theta border) relative power lower in pre-HD and early HD during REM relative to controls (p < 0.00125) | Relative power in 5–7 Hz range in HD during REM negatively correlated with disease burden score (DBS) | None | |
| 6–7 Hz range (theta and alpha–theta border) relative power lower in pre-HD and early HD during NREM relative to controls (p < 0.00125) | ||||||||||
| Piano et al. (42) | 2015 | LORETA | 46 | 23 | 0 | 23 | Alpha power higher in HD during NREM relative to control (p < 0.01) | Delta LORETA power negatively correlated with Unified Huntington’s Disease Rating Scale (UHDRS) during wake | None | Includes a literature review table that goes back further than the one in this review |
| Alpha power lower in HD during REM relative to control (p < 0.01) | ||||||||||
| Beta power lower in HD during NREM relative to control (p < 0.01) | Alpha, beta, and theta LORETA power positively correlated with UHDRS during NREM | |||||||||
| Theta power lower in HD during NREM and REM relative to control (p < 0.01) | ||||||||||
| Delta power higher in HD during wake relative to control (p < 0.01) | ||||||||||
| Ponomareva et al. (43) | 2014 | qEEG | 58 | 29 | 29 | 0 | 8–9 Hz range (alpha) relative power lower in pre-HD relative to control (p < 0.05) | Alpha, theta, and delta relative power positively correlated with DBS in pre-HD | CAG repeat length positively correlated with delta and theta relative power, 4–5 and 5–6 Hz bin relative power | |
| 7–8 Hz range (alpha–theta border) relative power lower in pre-HD relative to control (p < 0.01) | Extreme positive correlation between the difference of relative power between 7–8 and 4–5 Hz bin and DBS | Negatively correlated with alpha relative power, 7–8, 9–10, and 10–11 Hz bin relative power | ||||||||
| Delta and theta relative power negatively correlated with FAS score | ||||||||||
| Alpha relative power positively correlated with FAS score | ||||||||||
| Extreme positive correlation between the difference of relative power between 7–8 and 4–5 Hz bin and FAS score | ||||||||||
| Painold et al. (44) | 2011 | LORETA | 110 | 55 | 0 | 55 | Alpha LORETA power lower in HD relative to control (p < 0.05) | Alpha LORETA power positively correlated with Mini Mental State Examination (MMSE) score | None | Delta power observations were primarily in later stages of HD |
| Beta LORETA power lower in HD relative to control (p < 0.05) | ||||||||||
| Theta LORETA power lower in HD relative to control (p < 0.05) | Theta and alpha LORETA power negatively correlated with UHDRS | |||||||||
| Delta LORETA power higher in HD relative to control (p < 0.05) | ||||||||||
| Painold et al. (49) | 2010 | EEG Mapping | 110 | 55 | 0 | 55 | Absolute alpha power lower in HD relative to control (p < 0.05) | Absolute alpha power positively correlated with MMSE score and negatively with UHDRS | None | |
| Absolute beta power lower in HD relative to control (p < 0.05) | Absolute beta power positively correlated with MMSE and UHDRS scores | |||||||||
| Absolute theta power higher in HD relative to control (p < 0.05) | Absolute delta power positively correlated with MMSE score and negatively with UHDRS | |||||||||
| Absolute delta power higher in HD relative to control (p < 0.05) | Absolute theta power negatively correlated with MMSE and UHDRS scores | |||||||||
| Hunter et al. (45) | 2010 | qEEG | 42 | 15 | 3 | 24 | Absolute delta power higher in HD relative to control (p = 0.0000001) | Absolute alpha power negatively correlated with MMSE, digit symbol, and Stroop reading scores | Relative delta power AP gradient negatively correlated with CAG-repeat length | Absolute alpha power increase was only significant when medicated patients were included in analysis |
| Relative alpha anterior–posterior (AP)-gradient lower in HD relative to control (p = 0.000004) | Relative alpha AP-gradient positively correlated with Burden Pathology Score (BPS) score and negatively with Total Functional Capacity (TFC) and Stroop reading scores | |||||||||
| Relative delta AP-gradient lower in HD relative to control (p = 0.02) | Relative delta AP-gradient positively correlated with TFC score and negatively with BPS and Total Motor Symptoms scores | |||||||||
| Van der Hiele et al. (46) | 2007 | qEEG | 29 | 13 | 16 | 0 | Relative alpha power lower in Pre-HD relative to control (p = 0.003) | None | None | |
| Absolute alpha power lower in Pre-HD relative to control (p = 0.013) | ||||||||||
| Theta power unchanged in Pre-HD relative to control (p = 0.36) | ||||||||||
| De Tommaso et al. (47) | 2003 | qEEG | 33 | 13 | 7 | 13 | Absolute alpha power lower in HD relative to control (significance not reported) | None | None | No conclusions made regarding Pre-HD |
| Absolute theta power higher in HD relative to control (significance not reported) | ||||||||||
| Absolute delta power higher in HD relative to control (significance not reported) | ||||||||||
Base search terms included (EEG OR EEG Mapping OR qEEG) AND (Huntington’s Disease OR Huntington’s OR Huntington OR Huntington Disease). Additional terms included biomarker, preclinical, power spectral analysis, neural networks, and LORETA. Results were restricted to humans. Information noted includes recording modality used, the total number of subjects, the number of Huntington’s Disease (HD) subjects, the number of HDGEC/pre-HD subjects, the number of control subjects, any relevant qEEG-related findings, and correlations of those findings to clinical and genetic measures.