When Common Medications Quietly Affect the Brain

When Common Medications Quietly Affect the Brain

Memory loss and dementia rarely begin overnight. They often develop slowly and silently, years before symptoms become obvious. While aging, genetics, and lifestyle all play important roles, research now points to another often overlooked contributor: commonly used medications that affect brain chemistry and even brain structure.

If you are taking something for allergies, sleep, anxiety, depression, or bladder issues, it may be worth paying attention. Some of these medications belong to a group called anticholinergic drugs, and long-term use has been linked not only to memory loss and dementia, but also to measurable brain atrophy, meaning changes in brain volume and shape.

What are anticholinergic drugs?

Anticholinergic medications work by blocking acetylcholine, a neurotransmitter essential for memory, learning, attention, and muscle function. In the brain, acetylcholine plays a central role in forming new memories and maintaining cognitive clarity.

These drugs are widely prescribed and commonly sold over the counter, which is why many people take them daily without realizing their potential long-term neurological impact.

Common examples include:

• Allergy medications such as diphenhydramine (Benadryl)

• Sleep aids marketed as “PM” or nighttime formulas (including Unisom SleepTabs)

• Anti-anxiety medications such as hydroxyzine

• Medications for overactive bladder (Ditropan and similar drugs)

• Some antidepressants and motion-sickness medications

What does the research show?

Large population studies have raised serious concerns about cumulative exposure to anticholinergic drugs.

One widely cited study published in JAMA Internal Medicine found that taking a strong anticholinergic medication daily for as little as 12 months was associated with up to a 50% increased risk of dementia later in life.

Another major analysis pooling 21 studies involving 1,564,181 individuals found that people exposed to anticholinergic medications for more than three months had a 46% higher risk of dementia, including Alzheimer’s disease. The risk increased with dose and duration, meaning the longer and more frequently these drugs were used, the higher the risk.

Brain imaging studies add another layer of concern. Long-term anticholinergic use has been associated with brain atrophy, including reduced total brain volume and shrinkage in memory-related regions such as the hippocampus.

What makes this especially important:

• The risk may persist even after stopping the medication

• Structural brain changes can begin years before symptoms appear

Why is the brain especially vulnerable?

As we age, acetylcholine levels naturally decline. Alzheimer’s disease itself is characterized by impaired acetylcholine signaling. When medications further block this pathway, the brain may struggle to compensate

Over time, this can contribute to:

• Memory lapses

• Brain fog

• Reduced attention

• Slower processing speed

• Increased vulnerability to neurodegeneration and brain shrinkage

What can you do?

This does not mean stopping medications abruptly. Many people take these drugs for valid reasons. The goal is an informed, prevention-focused conversation, especially when medications are used long-term.

If you are taking 

• Hydroxyzine for anxiety

• Benadryl or Unisom regularly for sleep

It may be worth discussing alternatives with your doctor or pharmacist.

In some cases, options may include:

• Lower-risk pharmaceutical alternatives

• Dose reduction

• Short-term rather than chronic use

• Non-drug strategies for sleep and anxiety

Supporting the brain naturally

Alongside medication review, there is growing interest in natural compounds that support brain health without blocking acetylcholine.

1. Melatonin and chamomile
   Often used to support sleep regulation without anticholinergic effects.
2. Ashwagandha
   Traditionally used to support stress resilience and nervous system balance. Chronic stress is strongly linked to memory impairment and hippocampal shrinkage.
3. Lion’s Mane mushroom
   Studied for its role in supporting nerve growth factor (NGF), which is involved in neuron repair, regeneration, and cognitive function