Affective symptoms and AT(N) biomarkers in mild cognitive impairment and Alzheimer’s disease: A systematic literature review

• Published in: Neuroscience and biobehavioral reviews 2019-12, Vol.107, p.346-359
• Main Authors: Banning, Leonie C.P., Ramakers, Inez H.G.B., Deckers, Kay, Verhey, Frans R.J., Aalten, Pauline
• Format: Article
• Language: English
• Subjects: Affective symptoms; Alzheimer’s disease dementia; Biomarkers; Mild cognitive impairment; Neurocognitive disorders; Systematic review
• ISSN: 0149-7634; 1873-7528
• DOI: 10.1016/j.neubiorev.2019.09.014

•The AD biomarker - affective symptoms relationship shows inconsistent evidence.•Study designs assessing this relationship are very heterogeneous.•Majority of studies on depression show no relationship with AT(N) markers.•Future research should focus on possible subtypes of affective symptoms. Alzheimer’s disease (AD) biomarkers such as amyloid, p-tau and neuronal injury markers have been associated with affective symptoms in cognitively impaired individuals, but results are conflicting. CINAHL, Embase, PsycINFO and PubMed were searched for studies evaluating AD biomarkers with affective symptoms in mild cognitive impairment and AD dementia. Studies were classified according to AT(N) research criteria. Forty-five abstracts fulfilled eligibility criteria, including in total 8,293 patients (41 cross-sectional studies and 7 longitudinal studies). Depression and night-time behaviour disturbances were not related to AT(N) markers. Apathy was associated with A markers (PET, not CSF). Mixed findings were reported for the association between apathy and T(N) markers; anxiety and AT(N) markers; and between agitation and irritability and A markers. Agitation and irritability were not associated with T(N) markers. Whereas some AD biomarkers showed to be associated with affective symptoms in AD, most evidence was inconsistent. This is likely due to differences in study design or heterogeneity in affective symptoms. Directions for future research are given.