HoldsUp

Mark Mattson

Johns Hopkins University School of Medicine

Mark Mattson is a neuroscientist, an adjunct professor of neuroscience at the Johns Hopkins University School of Medicine, and the former chief of the Neuroscience Research Laboratory at the National Institute on Aging. His research focuses on the cellular and molecular effects of dietary restriction, intermittent fasting, and metabolic switching on aging, longevity, and metabolic traits. He also studies mechanisms of neuroprotection, synaptic plasticity, neurogenesis, and the principle of hormesis in brain health.

82 claims checked on air: 4 context 2 contradicted 68 supported 8 unverified

What they said on air - contradicted

7 citing their own research

0:44:05contradictedvery lowDr. Mark Mattson on the Benefits of Stress, Metabolic Switch

In a study by Alexis Stranahan, leptin-receptor-defective diabetic mice had fewer dendritic synapses in the hippocampus than normal mice under all tested conditions.

"she simply counted—not simply, it actually takes a lot of work, but counted synapses and found that, two things: one, the diabetic mice, regardless of whether they were intermittent fasting or had running wheels in their cages, had smaller number of synapses than did the normal mice." (said at 0:44:05)

In a study specifically investigating hippocampal neuron morphology in leptin-receptor-deficient diabetic (db/db) mice subjected to voluntary wheel running and caloric restriction, Alexis Stranahan and colleagues found the opposite of the speaker's claim: running wheel activity, dietary restriction, and their combination significantly increased hippocampal dendritic spine density on dentate granule neurons, rather than db/db mice failing to increase spine/synapse numbers under these conditions. While untreated diabetic mice exhibit baseline reductions in synaptic plasticity, spine density, and neurogenesis compared to control animals, exercise and dietary restriction actively attenuated and enhanced dendritic spine density in these mice.

1:41:30contradictedlowDr. Mark Mattson on the Benefits of Stress, Metabolic Switch

Chronic uncontrollable psychosocial stress is associated with decreased levels of mineralocorticoid receptor (MR) and increased levels of glucocorticoid receptor (GR) in brain neurons.

"people who are, you know, whether it's their work or life situation, they're chronically stressed out, they have elevated cortisol levels, and it's been shown that in that case in the brain, nerve cells in the brain have a decreased level of one of the cortisol receptors, the MR, and an increase in GR." (said at 1:41:30)

The speaker's statement bundles two claims about corticosteroid receptor changes in the brain under chronic stress: a decrease in mineralocorticoid receptors (MR) and an increase in glucocorticoid receptors (GR). While preclinical models and post-mortem studies consistently show that chronic stress downregulates limbic MR expression and reduces the MR/GR ratio, chronic stress typically downregulates or impairs hippocampal GR levels and signaling (contributing to impaired negative feedback of the HPA axis), rather than increasing GR expression in brain neurons.

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