Affective Symptoms in Early Adulthood Linked to Memory Loss and Cognitive Decline
https://neurosciencenews.com/early-depression-memory-loss-10934/
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/793ACA061D1FCADB853235F7DD9B83A1/S0007125019000242a.pdf/longitudinal_associations_of_affective_symptoms_with_midlife_cognitive_function_evidence_from_a_british_birth_cohort.pdf
A study published in the British Journal of Psychiatry suggests that a history of experiencing symptoms related to affective disorders, such as major depression and anxiety, may predict the occurrence and intensity of later cognitive decline. Participants were pulled from the National Child Development Study (NCDS), a group of 18,558 individuals born in England, Wales, and Scotland over the course of a single week in 1958; the NCDS collected data such as socio-economic position and education on these individuals at eight different intervals between the ages of 7-50, which were utilized as covariates. At ages 23, 33, 42, and 50, participants were administered the Malaise Inventory Scale, a 24-item questionnaire which assesses emotional disturbances and their associated somatic symptoms. At age 50, participants were assessed on a variety of cognitive measures: verbal memory, measured using a word-recall test; verbal fluency, utilizing a task where participants were asked to name as many animals as possible within one minute; and information processing speed & accuracy, measured through a task asking participants to cross specified characters in a grid of letters over the course of one minute - the total number of letters crossed indicated processing speed, and the number of targets missed was negatively scored as processing accuracy. Analysis of the affective trajectories of the 9,385 participants who completed the cognitive tests at age 50 showed initially high affective symptoms which increased throughout adulthood were strongly associated with poorer verbal memory & fluency beginning in mid-life, initially low and increasing affective symptoms were associated with poorer verbal memory and information processing speed by age 50, and initially high and decreasing affective symptoms or consistently low affective symptoms were associated with lower immediate memory scores in mid-life. The researchers suggested that chronic stress and affective symptoms may increase glucocorticoid production in the hypothalamic-pituitary-adrenal (HPA) axis, which in turn may lead to atrophy of the hippocampus and cognitive dysfunction; stress and affective symptoms were also associated with cardio-metabolic disorders, which share a link with Alzheimer's disease and general cognitive decline.
In Brain Rules, John Medina elaborates on the impact of chronic stress and its influence on the production of glucocorticoids. Stress triggers the production of glucocorticoids such as cortisol in the adrenal glands, which can have a particularly destructive impact on the hippocampus - acute stress can cause memories to be repressed as neural networks are disconnected, and over time glucocorticoids can halt the production of neurons and even kill existing neurons (Medina, 2014, p. 66-7). Affective disorders place individuals under unnatural, chronic stress, accelerating the negative effects of these stress hormones. Although the presence of neurotrophins - proteins which protect neurons from decay - prevents bouts of acute stress from causing lasting damage to the hippocampus, chronic stress can eventually "overwhelm" these neurotrophins (Medina, 2014, p. 68).
While the damage associated with chronic stress can be rather severe, the study notes the importance of structured, preventative mental health care, as expressions of cognitive decline were most strongly associated with affective trajectories - the development of symptoms over decades - rather than individual episodes.
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/793ACA061D1FCADB853235F7DD9B83A1/S0007125019000242a.pdf/longitudinal_associations_of_affective_symptoms_with_midlife_cognitive_function_evidence_from_a_british_birth_cohort.pdf
A study published in the British Journal of Psychiatry suggests that a history of experiencing symptoms related to affective disorders, such as major depression and anxiety, may predict the occurrence and intensity of later cognitive decline. Participants were pulled from the National Child Development Study (NCDS), a group of 18,558 individuals born in England, Wales, and Scotland over the course of a single week in 1958; the NCDS collected data such as socio-economic position and education on these individuals at eight different intervals between the ages of 7-50, which were utilized as covariates. At ages 23, 33, 42, and 50, participants were administered the Malaise Inventory Scale, a 24-item questionnaire which assesses emotional disturbances and their associated somatic symptoms. At age 50, participants were assessed on a variety of cognitive measures: verbal memory, measured using a word-recall test; verbal fluency, utilizing a task where participants were asked to name as many animals as possible within one minute; and information processing speed & accuracy, measured through a task asking participants to cross specified characters in a grid of letters over the course of one minute - the total number of letters crossed indicated processing speed, and the number of targets missed was negatively scored as processing accuracy. Analysis of the affective trajectories of the 9,385 participants who completed the cognitive tests at age 50 showed initially high affective symptoms which increased throughout adulthood were strongly associated with poorer verbal memory & fluency beginning in mid-life, initially low and increasing affective symptoms were associated with poorer verbal memory and information processing speed by age 50, and initially high and decreasing affective symptoms or consistently low affective symptoms were associated with lower immediate memory scores in mid-life. The researchers suggested that chronic stress and affective symptoms may increase glucocorticoid production in the hypothalamic-pituitary-adrenal (HPA) axis, which in turn may lead to atrophy of the hippocampus and cognitive dysfunction; stress and affective symptoms were also associated with cardio-metabolic disorders, which share a link with Alzheimer's disease and general cognitive decline.
In Brain Rules, John Medina elaborates on the impact of chronic stress and its influence on the production of glucocorticoids. Stress triggers the production of glucocorticoids such as cortisol in the adrenal glands, which can have a particularly destructive impact on the hippocampus - acute stress can cause memories to be repressed as neural networks are disconnected, and over time glucocorticoids can halt the production of neurons and even kill existing neurons (Medina, 2014, p. 66-7). Affective disorders place individuals under unnatural, chronic stress, accelerating the negative effects of these stress hormones. Although the presence of neurotrophins - proteins which protect neurons from decay - prevents bouts of acute stress from causing lasting damage to the hippocampus, chronic stress can eventually "overwhelm" these neurotrophins (Medina, 2014, p. 68).
While the damage associated with chronic stress can be rather severe, the study notes the importance of structured, preventative mental health care, as expressions of cognitive decline were most strongly associated with affective trajectories - the development of symptoms over decades - rather than individual episodes.
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