Background: Aging is associated with an increasing risk of decline in cognitive abilities. The decline is, however, not a homogeneous process. There are substantial differences across individuals although previous investigations have identified individuals with distinct cognitive trajectories. Evidence is accumulating that lifestyle contributes significantly to the classification of individuals into various clusters. How and whether genetically related individuals, like twins, change in a more similar manner is yet not fully understood.
Methods: In this study, we fitted growth mixture models to Mini Mental State Exam scores (MMSE) from participants of the Swedish OCTO Twin study of oldest old monozygotic (MZ) and same-sex dizygotic (DZ) twins with the purpose of investigating whether twin pairs can be assigned to the same class of cognitive change.
Results: We identified 4 distinct groups (latent classes) whose MMSE trajectories followed various patterns of change over time: a class of stable and high performing individuals, two groups of high performers who declined at different annual rates, and a small group of impaired individuals who declined more rapidly. Notably, our analyses show that few individuals in fact could be assigned to the same class as their co-twin.
Conclusions: Our study provides evidence for more substantial impact of environmental, rather than genetic, influences on cognitive change trajectories in later life.

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Posted 04 Feb, 2020
Posted 04 Feb, 2020
Background: Aging is associated with an increasing risk of decline in cognitive abilities. The decline is, however, not a homogeneous process. There are substantial differences across individuals although previous investigations have identified individuals with distinct cognitive trajectories. Evidence is accumulating that lifestyle contributes significantly to the classification of individuals into various clusters. How and whether genetically related individuals, like twins, change in a more similar manner is yet not fully understood.
Methods: In this study, we fitted growth mixture models to Mini Mental State Exam scores (MMSE) from participants of the Swedish OCTO Twin study of oldest old monozygotic (MZ) and same-sex dizygotic (DZ) twins with the purpose of investigating whether twin pairs can be assigned to the same class of cognitive change.
Results: We identified 4 distinct groups (latent classes) whose MMSE trajectories followed various patterns of change over time: a class of stable and high performing individuals, two groups of high performers who declined at different annual rates, and a small group of impaired individuals who declined more rapidly. Notably, our analyses show that few individuals in fact could be assigned to the same class as their co-twin.
Conclusions: Our study provides evidence for more substantial impact of environmental, rather than genetic, influences on cognitive change trajectories in later life.

Figure 1

Figure 2
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