Table 3.
Results, region-of-interest analyses*
| Anatomic region† | Model | Total sample (n = 680) | SCD (n = 168) | MCI (n = 164) | Dementia (n = 348) | ||||
|---|---|---|---|---|---|---|---|---|---|
|
|
|
|
|
||||||
| β | p value | β | p value | β | p value | β | p value | ||
| Total WMH volume | Model 1 | −0.03 | 0.47 | ||||||
| Forceps major | Model 1 | −0.06 | 0.16 | ||||||
| Forceps minor | Model 1‡ | 0.05 | 0.20 | 0.16 | 0.04 | 0.04 | 0.63 | 0.03 | 0.66 |
| Model 2‡ | 0.26 | 0.02 | — | — | — | — | |||
| Anterior thalamic radiation | Model 1‡ | −0.01 | 0.85 | 0.05 | 0.55 | 0.07 | 0.45 | −0.07 | 0.24 |
| Corticospinal tract | Model 1 | 0.03 | 0.46 | ||||||
| Cingulum | Model 1 | −0.02 | 0.70 | ||||||
| Inferior fronto-occipital fasciculus | Model 1‡ | −0.05 | 0.23 | 0.05 | 0.53 | −0.02 | 0.78 | −0.10 | 0.06 |
| Inferior longitudinal fasciculus | Model 1‡ | −0.04 | 0.30 | 0.11 | 0.17 | −0.05 | 0.58 | −0.10 | 0.07 |
| Superior longitudinal fasciculus | Model 1 | −0.03 | 0.42 | ||||||
| Superior longitudinal fasciculus, temporal part | Model 1 | −0.03 | 0.46 | ||||||
| Uncinate fasciculus | Model 1 | −0.01 | 0.78 | ||||||
MCI = mild cognitive impairment; SCD = subjective cognitive decline; WMH = white matter hyperintensity.
Results are presented as standardized β. This assumption-free region-of-interest analysis served to identify strategic white matter tracts in which white matter hyperintensity volume is correlated with depressive symptoms, independent of total white matter hyperintensity burden. The Geriatric Depression Scale, as measure of depressive symptoms, was standardized into a z-score. We excluded the tract parahippocampal white matter (Johns Hopkins University atlas31) from our analyses because of the limited white matter hyperintensity in this tract. We first entered age, sex, centre and syndrome diagnosis into a linear regression model (Model 1). If regional volumes showed a significant (p < 0.05) association in Model 1, we added the normalized total white matter hyperintensity volume to the model (Model 2). To check if associations between depressive symptoms and anatomic regions differed according to diagnostic group, we included interaction terms (dummy diagnosis × anatomic region) in the model. When we found an interaction between syndrome diagnosis and anatomic region (p < 0.10), we stratified the results for syndrome diagnosis, and the stβ is displayed for each diagnostic group separately. When no significant interaction was found, the interaction term was removed from the model and the overall β was reported.
Johns Hopkins University diffusion tensor imaging white matter atlas.31
Significant interaction term; subsequently stratified for syndrome diagnosis.