Alzheimers Dement: Depression can increase the risk of cognitive decline in patients with subjective cognitive decline

Depressive symptoms (DS) and cognitive deterioration of subjective perception in the absence of clinically relevant cognitive impairment (subjective cognitive decline [SCD]) are known risk factors
for dementia.
In addition, both long-term stable SCD and long-term increased DS were associated
with an increased risk of dementia.
However, although these two symptoms often occur together, their temporal relationship and their relationship to objective cognitive decline before dementia have not been well studied
.
Therefore, there is ambiguity for typical time series, as well as ambiguity about the causal relationship between SCD and DS
.
On the one hand, DS may be a non-neurodegenerative cause of SCD, for example, due to negative bias metacognitive judgments
about one's own cognitive abilities.
In this case, DS should predict the development of SCD and should not necessarily indicate an increased
risk of dementia.
On the other hand, SCD can be a symptom of an underlying neurodegenerative process, while DS is a response to
changes in cognitive abilities.
In this case, degenerative dementia should appear after SCD and should indicate an increased
risk of dementia.

Recently, Luca Kleineidam and others in the Department of Neurodegenerative Diseases and Geriatric Psychiatry at the University Hospital Bonn in Germany published their research results
in the journal Alzheimers Dement.

The aim of the study was to clarify the relationship
between SCD and DS in a population-based cohort of older adults by studying their time series and typical development in the pre-dementia stages.
The associated risk of dementia in this cohort, as well as the associated risk
of cognitive decline in another sample of multicentric memory clinical SCD, was also studied.
These analyses aimed to improve understanding of the development of pre-dementia symptoms and used SCD and DS as risk indicators
.

The temporal relationship between SCD, DS and memory decline in the cohort of high elderly people (N = 3217) was analyzed using a latent difference score model, and was validated
using cox-regression for dementia conversion.
In 334 patients with unimpaired cognitive SCD from memory clinics, we examined the association
of degenerative vertebral spondylosis with cognitive decline and cerebrospinal fluid (CSF) Alzheimer's disease (AD) biomarkers.

Figure 3.
Effect
of time development of memory loss, SCD and depressive symptoms on their other symptoms.

Table 2.
The relationship between DS reporting mode and transition to all-cause dementia depends on the SCD status at baseline

1.
In the population-based cohort, SCD precedes DS
.
High DS is associated
with an increased risk of dementia transformation in patients with SCD.

Results from a mixed model of potential processes linking depressive symptoms at baseline (as measured with MADRS) with cognitive decline over time (as measured with ADAS-Cog 11
).
The higher the ADAS-Cog 11 value, the worse the cognitive function
.

3.
Results of a mixed model of potential processes, amyloid pathology (measured with CSF Aβ1-42) at baseline is associated
with changes in depressive symptoms over time (measured with MADRS).
Higher MADRS values indicate more
depressive symptoms.
Low cerebrospinal fluid Aβ1-42 values indicate more
amyloid lesions.

4.
In SCD patients in memory clinics, high DS was associated
with greater cognitive decline.
CSF Aß42 indicates an increase
in DS.

Figure 4.
In patients with memory clinical SCD, the relationship between
baseline depressive symptoms and cognitive decline (A) and baseline amyloid pathology and changes in depressive symptoms (B).

The findings suggest that during cognitive decline, SCD precedes DS
.
In patients with SCD, more DS was associated
with faster symptom progression and Alzheimer's disease (AD) biomarkers.
Thus, in individuals reporting SCD, DS may indicate an increased
risk of AD.
Future studies should confirm the temporal relationship between SCD and DS, as this may have implications for optimizing study design: if SCD causes DS, then the conditioning effects on DS (e.
g.
, sample selection or statistical adjustments) may introduce bias
when studying SCD outcomes and related factors.

Original source

Kleineidam L, Wagner M, Guski J, et al.
Disentangling the relationship of subjective cognitive decline and depressive symptoms in the development of cognitive decline and dementia [published online ahead of print, 2022 Oct 11].
Alzheimers Dement.
2022; 10.
1002/alz.
12785.
doi:10.
1002/alz.
12785