Apathy, which is characterized by a loss of motivation and interest, is frequently found in Alzheimer’s disease and Parkinson’s disease.

Apathy is manifested by several signs, including loss of motivation, initiatives, falling social activities, disinterest, emotional blunting, and a lack of energy. These signs must be systematically identified if they last more than two weeks.

How to differentiate apathy from depression?

It is not easy to differentiate apathy from depression, as some symptoms co-exist.

Here is a summary: 
– Symptoms of apathy include a loss of motivation and perseverance, a reduction in emotional responses, indifference, and social withdrawal. 
– Depression is characterized by sadness, anxiety, suicidal ideation, agitation, devaluation, pessimism, feeling of guilt, negative thoughts, dark thoughts, and loss of appetite. 
– Common symptoms of both disorders: disinterest in the environment, psychomotor retardation, fatigue, lack of energy, hypersomnia, lack of insight, lack of initiative, loss of hope. 
Apathy is more common than depression in Alzheimer’s disease, frontotemporal dementia, unlike Parkinson’s disease.

Apathy and Alzheimer’s disease

Apathy is one of the most common behavioral symptoms of Alzheimer’s disease, affecting up to 75% of patients (the average prevalence is reported to be 55% However, this percentage depends on the method of evaluation and the type of population targeted. 

It is present at all stages of Alzheimer’s disease, but its frequency increases with the severity of the disease, affecting 40% of patients in the mild stage, 80% in the moderate stage, and more than 90% in the severe stage of the disease.

It is manifested by a loss of interest in the environment, a drop in motivation, enthusiasm, spontaneity. 

Some studies have found a correlation between the severity of apathy and executive function disorders (anticipation, selection of an objective, planning, ability to adapt to changes). 

The link between apathy and cognitive decline has been little explored in Alzheimer’s disease. According to one study, the frequency of apathy increases with the severity of cognitive impairment. 

Interesting fact: Apathetic people who are considered healthy may perform poorly on cognitive tests, suggesting that apathy may be a warning sign for identifying people at risk. This hypothesis is confirmed by a follow-up study, which showed that apathetic at-risk subjects have a greater probability of later developing Alzheimer’s disease. 

Similarly, anosognosia (misunderstanding by a patient of a disorder), very common in Alzheimer’s disease, is mainly linked to apathy (for example, the patient is unaware that he lacks initiative, motivation, etc.).

Apathy and Alzheimer’s: the recommendation of the High Authority for Health

Apathy is a behavioral disorder that should be better diagnosed, according to the High Authority for Health (HAS, France). Apathy is often confused with depression, which explains why many patients wrongly take antidepressants.

The French health agency publishes new recommendations on apathy with the dual objective of: “precisely defining the diagnosis” and “recommending management favoring non-drug therapeutic means. »

According to the HAS, “non-drug interventions should be preferred, as they address the symptoms. These may be cognitive stimulation therapies, psycho-socio-cognitive rehabilitation or even group activities related to daily life…”.

The HAS recommends reducing drugs at risk of side effects that promote apathy.

Apathy is accompanied by dysfunction of certain regions of the brain

Most studies have reported that apathy is accompanied by poor functioning of certain regions of the brain.

A decrease in metabolism (characterized by a reduction in blood circulation) has been observed in the frontal and temporal cortex of apathetic Alzheimer’s patients.

There is a correlation between the severity of apathy and reduced frontal cortex activity.

The nuclear magnetic resonance technique has shown that the thickness of the frontal cortex and the cingulate cortex decreases (reflecting atrophy of these regions) in apathetic Alzheimer’s patients.

This study demonstrates that apathy is not only a psychological disorder, but that it is accompanied by a dysfunction of certain regions of the brain.

Parkinson disease

According to epidemiological data, the prevalence of apathy in Parkinson’s disease is estimated at 16-42%. This variability depends on the instrument used as well as on the composition of the populations examined. 

Its severity is generally not related to the severity of motor disorders. On the other hand, it seems to be linked to the importance of cognitive disorders, particularly executive ones. 

Apathy can appear in the parkinsonian without it suffering from depressive disorders and vice versa. 

Frontotemporal dementia

Apathy is one of the most common initial signs of  frontotemporal dementia.

Its prevalence is estimated at 70-90%, and it occurs at all stages of the disease. 

Patients are usually unaware of this disorder. Therefore, the diagnosis should primarily be based on information provided by the closest caregiver. 

The presence of apathy in a patient makes it possible to differentiate frontotemporal dementia from other forms of frontotemporal dementia (e.g. semantic dementia and primary progressive aphasia). 

In frontotemporal dementia, the severity of apathy is related to the severity of disturbances in the frontal cortex.

Apathy and vascular disease

A recent study in people over the age of 85 indicates that this category of the elderly population with vascular disease has an increased risk of suffering from apathy, but not depression, suggesting that these two disorders do not have the same cause. 

Evaluation

The management of apathy remains difficult today, largely due to the lack of standardized means to detect its presence and assess its severity. 

The first scale proposed was the Apathy Evaluation Scale (AES) and its abbreviated version, called Apathy Scale (AS).

The Neuropsychiatric Inventory is a reliable instrument to assess neuropsychiatric disorders in neurological diseases.

Another more specific scale is also used and is called the Apathy Inventory (AI).

More recently, two new instruments have been proposed: the Structured Interview for Apathy (SIA) and the Lille Apathy Rating Scale (LARS).

Apathy would increase the risk of cognitive impairment

Older people with apathy but without depressive symptoms have greater brain atrophy compared to those who are not apathetic.

According to the lead author of the study, memory loss is therefore not the only symptom associated with an abnormal decrease in brain volume, characteristic of pathological cerebral aging.

The researchers showed, using neuroimaging examinations, that the decrease in brain volume concerns both the gray matter (formed by the cell bodies of neurons that store information) and the white matter (formed by the axons and terminals that provide the connection between neurons).

These results, if confirmed, would identify apathetic people as individuals at risk of developing cognitive disorders. Source: Structural MRI correlates of apathy symptoms in older individuals without dementia: AGES-Reykjavik Study. Neurology, 2014.