What Happens when dementia related brain changes impact memory (such as in Alzheimer’s Disease and other Dementias)
Road Closed: The Hippocampal Blockage
In Alzheimer’s disease and related dementias, the hippocampus is often the first area of the brain to deteriorate. Imagine the memory highway system with construction barriers blocking the entrance—no new traffic can get through.
Why New Memories Can’t Form
When the hippocampus is damaged:
- Information still enters working memory (the on-ramp functions normally)
- The amygdala still evaluates emotional significance (the checkpoint operates)
- But the cataloging system on the highway is blocked or severely damaged
New experiences pile up at the entrance but can never reach long-term storage. This is why someone with dementia can:
- Remember their childhood home in vivid detail (old memory, already in cortical storage)
- Have a wonderful conversation with you
- Ask five minutes later if you’ve visited yet (new memory never consolidated)
The Cruel Paradox
The memory highway diagram reveals a profound and often heartbreaking truth about dementia: The person is still experiencing life fully in the moment. Their working memory, attention, emotions, and awareness are often intact. They’re having the experience—they just can’t continue on the road to keep maintain the memory.
This is why people with dementia:
- Can enjoy activities and express genuine pleasure in the moment
- Form emotional connections even without remembering the specific encounter
- May feel the emotion of an experience (processed by the amygdala) even when they can’t recall the details
- Often retain very old memories (roads built decades ago) while losing recent ones
What Remains Accessible
The “off-ramp” side of the diagram—those old memories, stored in the cortex—often remains accessible much longer. This is why:
- Long-term procedural memories (how to brush teeth, eat) persist
- Deeply encoded emotional memories stay vivid
- Recognition may work better than recall
- Familiar songs, smells, and rituals can trigger preserved memories
Caution ahead: The Amygdala’s emotional tagging
The Emotional Highway Still Functions (But May Misread the Signs)
Critically, the amygdala often continues working even as the hippocampus fails. This means:
- People with dementia still feel and process emotions
- They form emotional impressions even without factual memory
- How you make them feel matters, even if they won’t remember the encounter
- Emotional memories can persist as feelings without attached details
However, brain changes can affect emotional calibration. The amygdala’s “tagging system” may assign priority incorrectly:
- False alarms: A harmless situation triggers intense fear or anxiety (like thinking a caregiver is a stranger)
- Missed signals: A genuinely concerning situation doesn’t register as important
- Amplified responses: Normal emotions feel overwhelming and all-consuming
- Flattened responses: Reduced emotional reaction to events that would typically be significant
What this means for care: When someone with dementia has an intense emotional reaction that their brain’s alarm system may be misfiring. The emotion is real and deserves validation, even if the triggering event seems minor to you. Dismissing their feelings (“that’s nothing to be upset about”) invalidates their genuine emotional experience, while acknowledging the emotion (“I can see you’re feeling worried”) honors their reality.
What This Means for Care Partners
Understanding The Memory Highway™ helps explain behaviors that might otherwise seem confusing:
Repetitive Questions: They’re not being difficult—each time they ask feels like the first time because no new road was built from the previous answer.
Living in the Past: Old highways remain intact and accessible while new construction is impossible. The past feels more real because those roads still exist.
Emotional Truth Over Factual Truth: The amygdala checkpoint still works. They may not remember what you said, but they’ll remember how you made them feel.
The Present Moment Matters: Even though memories won’t stick, the experience is still real and valuable. Joy, comfort, connection, and dignity in the moment have profound meaning.
A Final Thought
The Memory Highway™ isn’t just a teaching tool—it’s a reminder that memory loss doesn’t erase the person. The experience of life continues, even when the ability to consolidate those experiences is compromised. Every interaction matters, every moment of connection is real, and the emotional highway continues to function long after the factual highway closes.
Understanding this system helps us meet people with dementia where they are: fully present in the moment, deserving of dignity and connection, living on roads that still work even as construction (detours, cautions signs) becomes impossible.
For additional resources on person-centered dementia care and evidence-based approaches, visit DementiAgility.com.