Brain Regions Affected by Depression, According to Research Findings
Depression and Hippocampal Shrinkage: A Closer Look
Depression, a common mental health disorder, has been found to be strongly associated with brain shrinkage, particularly in the hippocampus. This relationship is supported by several mechanisms, as detailed in a recent study conducted by an international team of researchers.
The hippocampus, a brain region essential for memory and mood regulation, is sensitive to chronic stress and elevated glucocorticoids (stress hormones) commonly found in prolonged depression. These hormones exert neurotoxic effects that cause dendritic atrophy (shrinkage of neuron branches) and inhibit the birth of new neurons (neurogenesis), especially in the dentate gyrus subregion.
Structural imaging studies consistently find reduced hippocampal volumes in people with depression compared to healthy controls, with the degree of shrinkage correlating to illness duration and cognitive impairments like memory deficits. Synaptic plasticity in the hippocampus is also disrupted in depression, with phenomena resembling long-term synaptic depression (LTD) observed, including weakening synapses and shrinking dendritic spines.
The decline in hippocampal volume and function is linked to decreased numbers of glial cells (which support neurons) and altered brain-derived neurotrophic factor (BDNF) signaling, both contributing to impaired neural survival and plasticity in depression. Elevated cortisol in depression inhibits growth of new hippocampal cells and leads to hippocampal shrinkage, which is related to memory loss symptoms often seen in depressed patients.
The study, which analyzed MRI scans from over 9,000 individuals, found that people who suffered from recurrent depression or early-onset depression (before the age of 21) had a significantly smaller hippocampus. Prolonged depression causes brain shrinkage, specifically in the hippocampus, which can intensify depressive symptoms as the hippocampus plays a major role in forming new memories and managing emotional responses.
Hickie, one of the study's authors, explained that the hippocampus is one of the most important regenerative areas of the brain. The damage to the hippocampus may be reversible with treatment, support, and time. Early intervention isn't just about easing psychological suffering, but also about preserving brain function. Emerging therapies like neuroplasticity exercises, mindfulness meditation, EMDR, and psychedelic-assisted therapy are being explored for their ability to boost hippocampal growth.
Mental health screenings in schools and colleges could be protective for brain health, as early detection and intervention can help prevent or mitigate the effects of depression on the brain. The study tilts the scale, indicating that depression comes first and the damage follows. This evidence supports the growing body of research that depression is a neurological condition with physical consequences.
- The study findings highlight the importance of mental health in the context of health-and-wellness, as recurrent depression or early-onset depression before the age of 21 is linked to a significantly smaller hippocampus, which can intensify depressive symptoms.
- Treatment for depression may not only alleviate psychological suffering but also potentially reverse damage to the hippocampus, a brain region crucial for memory and mood regulation, further emphasizing the interplay between science and mental health.
