Large-scale brain scan study reveals unexpected differences in motor and visual regions linked to depression

Good news!

This study seems to confirm that depression also affects motion and vision, which was, I believe, known for a very long time. They call it "a key surprising finding", which it is not!

"Researchers ... analyzed thousands of brain scans collected from a population sample, including people with subclinical symptoms. The results of their analyses ... identified various changes in the brain that appear to be associated with depression, some of which are inconsistent with earlier observations. ...

Consistent with earlier research, the researchers found that depression was linked to a reduction in gray matter in three brain regions: the frontal cortex, anterior cingulate cortex and insula. These areas of the brain are known to play a role in the regulation of emotions, decision-making, motivation and the internal processing of bodily sensations.

"A key surprising finding was that smaller brain regions in motor and visual regions were linked to higher levels of depression," ... "It has been known that reduced brain size in other (e.g., frontal) parts of the brain is linked to depression, but the location of these new results was surprising because we don't usually link symptoms of depression to sensory processing or motor action."

Earlier research had also linked depression to changes in regions in the basal brain, such as the amygdala and hippocampus. ... observed little evidence of this. ...

Toward a better understanding of depression

This study was one of the most detailed and comprehensive explorations of brain changes associated with depression to date. Overall, its findings suggest that depression affects a broad network of brain regions that have been implicated in important mental functions. ..."

"Key points

• Depression’s physical symptoms may have a direct neural explanation.
• A major new study found that motor and visual brain regions shrink in depression, not just frontal regions.
• The hippocampus, long linked to depression, showed no clear changes.

..."

From the abstract:

"Depression has been linked to reduced size of subcortical regions and abnormal functional connectivity in frontal and default mode networks. However, recent meta-analyses have failed to identify significant converging correlates of depression across the literature such that a conclusive mapping of the neuroimaging correlates of depression remains elusive.

We leveraged 23,417 participants across 6 population datasets to comprehensively establish the neuroimaging correlates of depression.

We found reductions in gray matter volume/cortical surface area associated with depression in the frontal cortex, anterior cingulate and insula, confirming previous studies showing the importance of prefrontal and default mode regions in depression.

Our findings demonstrate multiple surprising results, including a lack of depression correlates in subcortical brain regions and significant depression correlates in somatomotor and visual regions.

Overall, these results shed new light on key brain regions involved in the pathophysiology of depression, updating our understanding of the neuroimaging correlates of depression symptoms."

Large-scale brain scan study reveals unexpected differences in motor and visual regions linked to depression

Depression Doesn’t Just Affect the Thinking Brain "A new study of 23,000 people found unexpected brain changes in depression."

The neuroimaging correlates of depression established across six large-scale population datasets (open access)

Fig. 1: Overview of main analysis steps.

Fig 2 Fig. 2: Neuroimaging correlates of depression.

Neurogenesis of pain and depression in the hippocampus

Amazing stuff!

"Chronic pain and depression are mutually linked. Ding et al. explored the mechanistic link between chronic pain and depression in humans and rodents ... In patients and an animal model, early stages of chronic pain were found to be associated with an increase in hippocampal volume, whereas later stages were associated with decreased hippocampal volume.

These changes in rats were followed by the development of depressive-like behavior. Mechanistically, the authors showed that microglial activation leads to dysregulation of hippocampal neurogenesis (producing volumetric changes), shifts in hippocampal physiology, and onset depressive-like behaviors. The study provides valuable insights into the role of the hippocampus in the development of comorbid depression in the context of chronic pain."

From the abstract of the Perspective:

"Pain is classically defined as a sensory experience, yet it also engages emotional and cognitive processes. When pain becomes chronic—persists or recurs beyond 3 months from injury—it is frequently accompanied by disability and emotional dysregulation. Among these comorbidities, depression, anxiety, and sleep disorders are the most prevalent, yet the mechanistic relationships linking pain chronicity to these affective consequences remain poorly understood. On page 1235 and 1236 of this issue, Wei et al. (3) and Ding et al. (4), respectively, report evidence of pain-related brain regulation at two opposite ends of the temporal spectrum. Wei et al. describe a neural circuit that accounts for daily fluctuations in pain sensitivity. Meanwhile, Ding et al. identify cellular and structural brain changes that contribute to the emergence of depression in chronic pain. These observations offer new insight into how chronic pain becomes coupled to affective and cognitive comorbidities."

From the abstract:

"Structured Abstract

INTRODUCTION

Chronic pain is a leading risk factor for depression and anxiety, yet the brain mechanisms that convert persistent sensory distress into affective dysfunction remain unclear. Neuroimaging studies have implicated the hippocampus in both pain and mood regulation, but it is unknown whether hippocampal alterations precede, accompany, or result from the emergence of affective symptoms. Resolving this temporal and mechanistic relationship is essential for explaining individual vulnerability to depression in chronic pain and for identifying intervention points that can prevent this transition.

RATIONALE

We hypothesized that chronic pain induces a staged remodeling process, rather than a uniform degenerative change, within the hippocampus. Specifically, we proposed that the dentate gyrus serves as a critical gate where persistent nociceptive input is initially accommodated through adaptive plasticity but later diverted into maladaptive circuit destabilization by interactions between adult-born neurons and microglia.

RESULTS

Integrating longitudinal human neuroimaging data from the UK Biobank with rodent models of neuropathic pain, we identified a conserved biphasic trajectory of hippocampal remodeling. During early stages of chronic pain, hippocampal volume increased and hippocampal-dependent cognitive performance improved, consistent with an adaptive response. As pain persisted, this phase transitioned to hippocampal atrophy, cognitive decline, and the emergence of anxiety- and depression-like behaviors.

At the cellular level, early chronic pain selectively increased activity of newborn neurons within the dentate gyrus and triggered targeted recruitment and remodeling of microglia in the neurogenic niche. These cell-type–specific changes progressively amplified local circuit excitability and disrupted network balance, marking a transition from adaptive hippocampal plasticity to maladaptive circuit remodeling. Functionally, distinct modes of dentate gyrus modulation produced divergent outcomes: Suppressing newborn neuron activity alleviated affective symptoms but impaired cognition, whereas microglial modulation prevented anxiety- and depression-like behaviors while preserving cognitive function. Together, these findings identify microglia as a key regulator of the pain-to-depression transition.

CONCLUSION

By resolving distinct modes of dentate gyrus modulation, we show that microglia act as critical and therapeutically tractable regulators of the transition from chronic pain to affective disorders. Our findings reveal that this transition is governed not by hippocampal hyperactivity per se but rather by microglia-dependent remodeling that determines whether adaptive plasticity is sustained or diverted into maladaptive circuit states. Targeting microglial activation preserves hippocampal structure and cognitive function while preventing affective pathology, positioning microglia as a selective leverage point for interrupting the progression from chronic pain to mood disorders."

In Science Journals | Science

Pain across time (Perspective, no public access)

From chronic pain to depression: Neurogenesis-driven microglial remodeling in the hippocampal dentate gyrus (no public access)

FDA Approves tDCS headset for Depression Treatment at home

Good news!

"For years, a small group of technology enthusiasts have been applying gentle electrical current to their brains in an effort to gain cognitive benefits, improve sleep, or aid memory. While brain stimulation, also referred to as neuromodulation, can take many forms, transcranial direct current stimulation (tDCS) emerged as a reasonably safe, affordable choice for at-home experimentation for a range of purposes.

These devices have often been home-brewed or sold as wellness tools, but in her research into the do-it-yourself tDCS community, Anna Wexler, a medical ethicist at the University of Pennsylvania, found that in addition to brain boosting, many practitioners were self-medicating, using electrotherapy to treat symptoms of depression and anxiety. Until recently, there were no medical tDCS devices with U.S. Food and Drug Administration approval.

In December the FDA approved a tDCS headset produced by Flow Neuroscience for treatment of major depressive disorder. ..."

FDA Approves tDCS for Depression Treatment - IEEE Spectrum "Flow’s headset is the first tDCS device approved by the FDA"

Flow Neuroscience’s transcranial direct current stimulation device has been approved by the FDA to treat depression

Inflammation May Be the Link Between Chronic Pain, number of pain sites and Depression

This seems to be very plausible, if not plain obvious!

"Chronic pain—or pain that lasts at least three months—is closely intertwined with depression. Individuals living with pain’s persistent symptoms may be up to four times more likely to experience depression, research shows.

Almost 30% of people worldwide suffer from a chronic pain condition such as lower back pain and migraines, and one in three of these patients also report co-existing pain conditions.

Now, a new study published in Science Advances shows that a person’s risk of depression increases alongside the number of places in the body in which they experience pain. Furthermore, inflammatory markers such as C-reactive protein (a protein produced by the liver in response to inflammation) help explain the association between pain and depression.

This finding suggests that the mechanisms underlying chronic pain and depression may be driven by systemic inflammation, the researchers say. ..."

From the abstract:

"Chronic pain conditions frequently coexist and share common genetic vulnerabilities. Despite evidence showing associations between pain and depression, the additive effect of co-occurring pain conditions on depression risk and the underlying mechanisms remain unclear.

Leveraging data from 431,038 UK Biobank participants with 14-year follow-up, we found a significantly increased risk of depression incidence in individuals reporting pain, irrespective of body site or duration (acute or chronic), compared with pain-free individuals.

The depression risk increased with the number of co-occurring pain sites. Mendelian randomization supported potential causal inference.

We constructed a composite pain score by combining individual effects of acute or chronic pain conditions across eight body sites in a weighted manner.

We found that depression risks increased monotonically in parallel with composite pain scores.

Moreover, some inflammatory markers, including C-reactive protein, partially mediated the association between composite pain scores and depression risk. Considering the high prevalence of comorbid depression and pain, pain screening may help identify high-risk individuals for depression."

Inflammation May Be the Link Between Chronic Pain and Depression < Yale School of Medicine

The inflammatory and genetic mechanisms underlying the cumulative effect of co-occurring pain conditions on depression (open access)

Fig. 1. Overview of study workflow.

Fig. 2. Prospective associations of acute or chronic pain across eight body sites and incidence of depression.