Context: A strong relationship has been established between depression occurring in late life, the presence of subcortical vascular pathology, and features of dysexecutive frontal-subcortical cognitive and behavioural impairment. Various hypotheses have been put forward to explain this frequent association.
Objective: To put forward a simple hypothetical explanation for this association-that subcortical vascular pathology interferes with adaptive functions – functions which depend on the optimal functioning of an intact brain, but particularly on the optimal functioning of prefrontal networks.
Key messages: Human responses to extreme stress as in loss, trauma, and terror have been well delineated, particularly by Horowitz. His observations probably also apply to human responses to lesser stress and trauma, the accidental and developmental ‘crises’ or transitions which affect all human beings. Horowitz has also described psychotherapy and the path to recovery following these experiences. This, he says involves the person achieving an adaptive emotional equilibrium, processing the meanings of the stressor events, and reschematizing their identity and relationships. These are examples of the processes which can broadly be called adaptive, and which depend on the adaptive functions of the brain. These processes are particularly, but not exclusively, linked to frontal networks. Various components of the frontal network are recruited when humans face novel situations or challenges, situations not previously encountered. The processes which have long been described with terms such as “working through, coming to terms, integrating, moving on, letting go” all require relatively intact frontal networks. These networks are demonstrably not intact in dysexecutive vascular depression.
