Early Detection Markers of Alzheimer's Disease Possibly Identified

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Depressive symptoms are associated with lower psychomotor speed, whereas subjective memory complaint is linked to lower objective memory.
Depressive symptoms are associated with lower psychomotor speed, whereas subjective memory complaint is linked to lower objective memory.

Depressive symptoms (SDS) and subjective memory complaint (SMC) could be used as early detection markers of Alzheimer's disease, according to a study published in the Journal of Affective Disorders.

Eun Hyun Seo, MA, from the National Research Center for Dementia in South Korea, and colleagues performed clinical and neuropsychological assessments of 672 participants to find the association among SMC, SDS, and cognitive function in the elderly from cognitively normal (n=299), pre-mild cognitive impairment (n=106), and amnestic mild cognitive impairment (n=267) groups.

In addition to clinical and neuropsychological assessments, participants answered self-reported SMC and SDS questionnaires. Assessments administered that showed statistical significance included the Mini Mental Status Examination, Seoul Verbal Learning Test (SVLT) trials as immediate recall (SVLT_irl), 20-minute delayed recall (SVLT_drl), yes-no recognition (SVLT_rcg), Rey Complex Figure Test (RCFT) as immediate recall (RCFT_irl), 20-minute delayed recall (RCFT_drl), yes-no recognition (RCFT_rcg), animal fluency score (Fluency_A), stroop score for word reading (Stroop_W), stroop score for color reading (Stroop_C), and the trail making test (TMT_B).

SDS were significantly connected with the Stroop_W (R2 change=0.006;=.049) and Mini Mental Status Examination (R2 change=0.006; =.035) scores, whereas SMC was significantly connected with the SVLT_irl (R2 change=.013; =.003), RCFT_irl (R2 change=0.007; =.029), and RCFT_drl (R2 change=.006; =.049) scores.

Interactions between the SMC and SDS were also significantly associated with the SVLT_drl (R2 change=0.015; =.002), SVLT_rcg (R2 change=0.008; =.018), Fluency_A (R2 change=0.021; <.001), Stroop_W (R2 change=0.043; <.001), Stroop_C (R2 change=0.012; =.005), TMT_B (R2 change=0.028; <.001), and Mini Mental Status Examination (R2 change=0.036; <.001) scores.

These data suggest SDS are associated with lower psychomotor speed, whereas SMC is linked to lower objective memory. Interactions between SDS and SMC were significant in memory, executive function, psychomotor speed, and global cognition testing.

"Early identification of individuals at risk for developing abnormal cognitive changes is critical," Seo said. "Subjective memory complaint and depressive symptoms could be used as early detection markers of Alzheimer's disease."

Study Limitations

  • Because of the study's cross-sectional design, links between SDS, SMC, and cognitive function were significant, but relatively weak.
  • Future biomarker studies are required to better understand the underlying relationship between SDS, SMC, and cognitive function.

Reference

Seo EH, Kim H, Choi KY, Lee KH, Choo ILH. Association of subjective memory complaint and depressive symptoms with objective cognitive functions in prodromal Alzheimer's disease including pre-mild cognitive impairment. J Affect Disord. 2017;217:24-28.

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