Screening for Alzheimer’s Disease: Cognitive Impairment in Self-Referred and Memory Clinic-Referred Patients

Abstract

Background:Cognitive assessment is essential in tracking disease progression in AD. Presently, cohorts including preclinical at-risk participants are recruited by different means, which may bias cognitive and clinical features. We compared recruitment strategies to levels of cognitive functioning.Objective:We investigate recruitment source biases in self-referred and memory clinic-referred patient cohorts to reveal potential differences in cognitive performance and demographics among at-risk participants.Methods:We included 431 participants 40–80 years old. Participants were classified as controls (n = 132) or symptom group (n = 299). The symptom group comprised of subjective cognitive decline (SCD, n = 163) and mild cognitive impairment (MCI, n = 136). We compared cognitive performance and demographics in memory clinic-referrals (n = 86) to self-referred participants responding to advertisements and news bulletins (n = 179). Participants recruited by other means were excluded from analysis (n = 34).Results:At symptom group level, we found significant reductions in cognitive performance in memory clinic-referrals compared to self-referrals. However, here reductions were only found within the MCI group. We found no differences in cognitive performance due to recruitment within the SCD group. The MCI group was significantly impaired compared to controls on all measures. Significant reductions in learning, and executive functions were also found for the SCD group.Conclusion:Regardless of recruitment method, both the SCD and MCI groups showed reductions in cognitive performance compared to controls. We found differences in cognitive impairment for memory clinic-referrals compared to self-referrals only within the MCI group, SCD-cases being equally affected irrespective of referral type.

Cerebrospinal fluid neurogranin/β‐site APP‐cleaving enzyme 1 predicts cognitive decline in preclinical Alzheimer's disease

“…T-scores for the trail-making tests were calculated using published norms [34] . For the CERAD word list test, we used the normative performance of the DDI cohort control group [26] to calculate T-scores after a recent article that showed published norms not matching the younger and more educated DDI cohort [35] . A total of 42 of 74 baseline cases had available cognitive data at 2-year follow-up.…”

Amyloid Plaques and Symptoms of Depression Links to Medical Help-Seeking due to Subjective Cognitive Decline

“…While many studies have found recruitment source differences in both AD biomarker prevalence and cognitive performance in MCI [21,24,25], studies on SCD have been inconsistent [22,24,26,27]. A recent meta-analysis found no difference in the risk of progression of SCD patients recruited by different means [4].…”

“…However, patients who report SCD to their general practitioner (GP) may not be referred to a memory clinic for assessment [30]. In a previous study, we found no significant cognitive differences between SCD cases recruited from memory clinics as compared to SCD cases recruited from a community sample [24].…”

“…We and others have shown that MCI recruited through memory clinics also have poorer cognitive function than community samples [21,24,25]. However, while memory clinic SCD cases have shown higher conversion rates to MCI compared to community cases [23,26], and lower baseline cognitive performance in one study [27], most studies have not found any baseline cognitive differences in SCD cases due to recruitment source bias [22,24,26]. The biases observed from recruiting memory clinic SCD cases may stem from worries or concerns felt by either patients, or their families reaching a threshold prompting the person to seek medical help.…”

“…Recruitment of MCI and SCD participants through memory clinics include individuals with higher rates of abnormal CSF biomarkers and increased brain amyloid-␤ (A␤) deposition as compared to selfreferred participants from the community [20][21][22][23]. We and others have shown that MCI recruited through memory clinics also have poorer cognitive function than community samples [21,24,25]. However, while memory clinic SCD cases have shown higher conversion rates to MCI compared to community cases [23,26], and lower baseline cognitive performance in one study [27], most studies have not found any baseline cognitive differences in SCD cases due to recruitment source bias [22,24,26].…”