Philippians 4:6-7

King James Version

⁶ Be careful (anxious) for nothing; but in every thing by prayer and supplication with thanksgiving let your requests be made known unto God.

⁷ And the peace of God, which passeth all understanding, shall keep your hearts and minds through Christ Jesus. 

The word in the scriptures here is “merimnaō” (μεριμνάω), which means "to be anxious about, to have a distracting care,".

I really do not believe that the Holy Spirit had St. Paul and other biblical writers include things in their letters, for no reason. Yes, on it’s surface its talking about not being anxious, because our trust is in God. But, in addition to that, science has also revealed to us why we shouldn’t be. Because it costs us brain power.

How Stress Can Make Your Brain Smaller: A Simple Explanation

(a more detailed study is below)

Did you know that when we feel stressed for a long time, it can actually change the shape of our brain? One special part of the brain, called the hippocampus, gets smaller if we're under too much stress. The hippocampus helps us remember things and manage our emotions, so it's really important! Here’s how stress affects it:

1. Too Much Cortisol:

When we’re stressed, our body makes a hormone called cortisol. This is okay in small amounts, but when we feel stressed all the time, too much cortisol can hurt the cells in the hippocampus, making it smaller.

2. Fewer New Brain Cells:

The hippocampus is one of the few places in the brain where new brain cells can grow, even when we’re adults! But stress makes it harder for these new cells to grow, so fewer new brain cells means the hippocampus doesn’t stay healthy and strong.

3. Problems with Memory:

Stress can make it harder for the connections between brain cells to work well. These connections are what help us remember things and learn new stuff. When stress weakens these connections, it can affect our memory, and the hippocampus gets weaker.

4. Too Much Excitement in the Brain:

When we’re stressed, our brain releases more of a chemical called glutamate, which helps the brain cells communicate. But too much glutamate can make the brain overactive, hurting brain cells and causing the hippocampus to shrink.

5. Inflammation in the Brain:

Stress can make our brain become inflamed, just like when we get a bruise or a cut. This inflammation hurts the brain cells in the hippocampus, which can make it smaller over time.

6. Less Blood for the Brain:

Stress can also reduce blood flow to the brain, which means the brain doesn’t get enough oxygen or nutrients. Without these, the hippocampus can’t stay healthy and might shrink.

What Happens When the Hippocampus Shrinks?

We might forget things more easily.

Our emotions might feel harder to control.

It can make it more likely for us to feel really sad or worried.

So, it’s important to take breaks, relax, and find ways to handle stress to keep our brain healthy!

Stress can lead to the reduction in the size of the hippocampus, a brain region critical for learning, memory, and emotional regulation. This process is linked to various biological mechanisms and involves the following pathways:

1. Chronic Activation of the HPA Axis:

Stress activates the hypothalamicpituitaryadrenal (HPA) axis, which leads to the release of glucocorticoids (mainly cortisol in humans). While cortisol helps the body respond to stress, chronic stress leads to overexposure to high cortisol levels.

Prolonged cortisol exposure damages neurons in the hippocampus, leading to a reduction in dendritic branches and synaptic connections.

2. Impact on Neurogenesis:

The hippocampus is one of the few brain regions where adult neurogenesis (the formation of new neurons) occurs, particularly in the dentate gyrus.

Chronic stress suppresses neurogenesis through elevated cortisol levels, leading to fewer new neurons being produced, which in turn results in a reduction of hippocampal volume.

3. Synaptic Plasticity and Memory Impairment:

Stress impairs synaptic plasticity, which is the ability of synapses (connections between neurons) to strengthen or weaken over time. This impairs longterm potentiation (LTP), a key mechanism underlying learning and memory.

As synaptic connections degrade under chronic stress, the hippocampus loses functionality, contributing to memory deficits and a decrease in hippocampal volume.

4. Excitotoxicity:

Chronic stress leads to increased levels of glutamate, an excitatory neurotransmitter. Excessive glutamate can cause excitotoxicity, which damages and kills neurons by overactivating NMDA receptors, further contributing to hippocampal shrinkage.

5. Inflammation:

Chronic stress is associated with increased inflammation in the brain, as well as the release of proinflammatory cytokines. Inflammation has been shown to contribute to neuronal damage in the hippocampus, further decreasing its size over time.

6. Impaired Blood Flow:

Stress can also negatively affect cerebral blood flow, which impairs the delivery of oxygen and nutrients to the hippocampus, further exacerbating neuronal loss and hippocampal atrophy.

Consequences of Hippocampal Shrinkage:

 Cognitive deficits, particularly in memory formation and retrieval.

 Emotional dysregulation, since the hippocampus is involved in modulating stress responses and emotions.

Increased vulnerability to psychiatric disorders like depression, anxiety, and posttraumatic stress disorder (PTSD), all of which are associated with reduced hippocampal volume.

Research Findings:

Numerous studies have shown a correlation between chronic stress and hippocampal shrinkage. For example:

 Neuroimaging studies in humans show that individuals exposed to prolonged stress, such as those with PTSD or major depressive disorder, tend to have smaller hippocampi.

 Animal studies have demonstrated that stressors like social defeat or chronic restraint reduce hippocampal size and impair memory performance.

Here are two scholarly articles on how stress affects hippocampal volume:

1. [Stress and Loss of Adult Neurogenesis Differentially Reduce Hippocampal Volume](https://www.sciencedirect.com/science/article/pii/S0006322317315858)

- Authors: TJ Schoenfeld, HC McCausland, HD Morris

- Published in Biological Psychiatry, 2017.

- Read more on NIH

2. [Parsing the Hippocampus in Depression: Chronic Stress, Hippocampal Volume, and Major Depressive Disorder](https://www.biologicalpsychiatryjournal.com/article/S0006-3223(19)30037-X/abstract)

- Authors: YI Sheline, C Liston

- Published in Biological Psychiatry, 2019.