Episodic Memory in Alzheimer's Disease

Remembering recent events is a key aspect of episodic memory. This type of memory helps us recall personal experiences and events that have occurred in our lives.

The hippocampus, located in the temporal lobe, plays a crucial role in forming and retrieving episodic memories. Damage to this brain region can lead to impairments in remembering personal experiences.

In Alzheimer's Disease (AD), the hippocampus is often one of the first brain regions to be affected. Atrophy, or shrinkage, in the hippocampus can cause significant problems with memory formation and retrieval, particularly for recent events.

Recall involves actively searching for a specific memory, while recognition uses cues like seeing the item again to trigger remembrance. Both are impaired in AD, suggesting a problem with memory formation itself, not just retrieval.

Studies have shown that deficits in recall and recognition can be observed in individuals years before they are officially diagnosed with Alzheimer's Disease (AD). This suggests that memory impairments can be an early indicator of the disease.

Whitwell et al. (2007) found that people who later developed AD showed shrinkage in specific areas of the brain, including the hippocampus. This shrinkage is linked to a decline in memory function.

In Alzheimer's Disease, episodic memory is often severely impaired. The difficulty remembering recent events is one of the earliest and most prominent features of the disease.

Both recall and recognition abilities decline in AD, suggesting that the problem is not just about retrieving memories, but also about the ability to form them in the first place.

The medial temporal lobe, particularly the anterior inferior and medial regions, plays a crucial role in episodic memory. Atrophy in these areas is a hallmark of early-stage AD.

The left hemisphere of the brain is dominant for language processing, with the anterior temporal lobe and inferior frontal lobe critical for understanding and producing words.

Atrophy in the language processing areas of the brain, particularly the left anterior temporal lobe and inferior frontal lobe, can lead to semantic and language deficits in AD.

The Category Fluency Task, a common test for semantic memory, assesses the ability to name as many items from a specific category (e.g., animals) as possible in a limited time. AD patients often struggle with this task.

AD can affect semantic memory, leading to vocabulary shrinkage and difficulty retrieving less frequently used words. However, very early learned words are often preserved, requiring significant atrophy before they are forgotten.

Impaired object naming in AD is often associated with cortical thinning in the left anterior temporal lobe, a region also affected in semantic dementia.

Transcranial Magnetic Stimulation (TMS) can be used in cognitive neuroscience to temporarily inhibit specific brain areas. In AD, inhibiting the anterior temporal lobe through TMS disrupts semantic tasks, mimicking the effects of dementia.

The frontal lobes are essential for controlling thought and behaviour (executive function), including concentration, decision-making, and planning. These functions are frequently impaired in AD.

AD patients often experience dual-task impairments, struggling to coordinate multiple activities simultaneously, indicating a problem with flexibly allocating attention.