Growing evidence suggests a link between Alzheimer’s disease and depression. Depression can also be a risk factor for developing Alzheimer’s disease later in life.

Depression is a mental health condition that causes marked disruptions in a person’s emotional state.

Alzheimer’s disease (AD) is a brain disorder that causes a gradual decline in thinking, memory, and other mental skills.

Depression symptoms are common in people with AD. Studies also show that AD and other forms of dementia more commonly develop in people with depression.

Read on to learn more about the link between depression and Alzheimer’s disease.

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Depression is not a diagnostic criterion for AD, but the two diseases do have associations. Depression often occurs in the early to middle stages of AD.

Significant depression is present in about three-quarters of people with AD. According to other research, having depression may worsen the outlook of AD and accelerate its progression.

Growing research suggests a relationship between AD and depression. Although some people with AD have depression, it remains unclear if depression is a risk factor for AD, an early symptom, or a reaction to cognitive deficits experienced in AD. Some researchers suggest that they have a reciprocal relationship.

People with mental health conditions, such as depression, have up to four times higher risk of developing dementia or other neurodegenerative disorders later in life.

Depression is a potential risk factor for cognitive decline and AD progression, even over 20 years after receiving a depression diagnosis.

Having depression is also a predictor of AD in people who do not carry the apolipoprotein E (ApoE) allele.

Scientists have found that the two conditions share a common genetic and molecular pathophysiology. A 2019 review explains how depression may lead to AD development.

It describes three shared neurobiological features between late-life depression and AD. The review proposes that neuroinflammation, cerebrovascular disease, and neurodegeneration cause the brain to lower the threshold for AD presentation.

Learn more about depression.

Identifying depression in people with AD can be challenging since they cause similar symptoms. Cognitive decline may also limit the ability to articulate one’s feelings and affect self-awareness of depression symptoms.

Depression may appear differently in people with AD. They may not report a depressed mood. Instead, they may have non-specific symptoms, such as:

Some features that may suggest depression in people with AD include:

  • frequent use of medical services and office visits
  • persistent reports of fatigue and pain
  • headache
  • changes in sleep and appetite
  • unexplained gastrointestinal symptoms
  • social isolation
  • increased dependency

Depression symptoms in people with AD may also be less severe. The symptoms may not last as long and may tend to come and go.

Learn about the hidden signs of depression.

Doctors often find it challenging to diagnose depression in people with AD because they cause similar symptoms. There is no single test to detect depression in AD. Diagnosis requires a thorough evaluation with a skilled healthcare professional.

The evaluation will typically include the following:

  • a thorough review of medical history
  • a physical and mental examination
  • family interviews

Some people with depression in AD may not meet the full criteria for major depressive disorder (MDD) as listed in the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR). There are separate guidelines for diagnosing depression in people with AD.

For a doctor to diagnose depression in AD, a person must have a depressed mood or decreased pleasure in usual activities, with at least two of the following:

  • withdrawal or social isolation
  • changes in sleep
  • changes in appetite
  • agitation or slowed behavior
  • irritability
  • fatigue or loss of energy
  • feelings of worthlessness or inappropriate or excessive guilt
  • recurrent thoughts of death or suicide

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

  • Ask the tough question: “Are you considering suicide?”
  • Listen to the person without judgment.
  • Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
  • Stay with the person until professional help arrives.
  • Try to remove any weapons, medications, or other potentially harmful objects if it’s safe to do so.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Find more links and local resources.

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Treatment of depression in AD often involves a combination of medicines, therapy, and daily life adaptations.

Medications for depression typically include serotonin-specific reuptake inhibitors (SSRIs). For non-medication approaches, psychotherapies, specifically cognitive behavioral therapy (CBT), may help.

Other non-medical approaches for depression in AD may include:

  • joining support groups
  • creating a predictable daily routine
  • planning and scheduling enjoyable activities
  • helping with tasks

The following activities may also provide comfort and reassurance to a person with dementia and depression:

  • regular physical activity
  • one on one interaction with another person
  • regular activities with other people, including reminiscence and life story activities
  • environmental changes such as removing clutter and reducing bright lights and loud noises

Learn more about activities for dementia.

The American Academy of Family Physicians (AAFP) recommends screening people with AD for depression.

A person should consider contacting a doctor if they notice symptoms of depression or other changes in behavior in their loved ones with AD.

The following are some questions people frequently ask about depression and Alzheimer’s disease.

At which stage of AD can depression occur?

Depression commonly occurs during the early and middle stages of AD.

What do AD and MDD have in common?

Symptoms of AD and MDD tend to overlap. Some symptoms common to both AD and depression include:

  • loss of interest in activities previously enjoyed
  • apathy
  • isolation
  • social withdrawal
  • impaired thinking
  • difficulty concentrating

Studies show a clear association between depression and Alzheimer’s disease. Depression is a risk factor for developing AD later in life. People with AD have a higher chance of developing depression.

The presence of both conditions can make diagnosis challenging. There is no single test to diagnose depression in a person with AD, but a thorough medical evaluation can help.

Speak to a medical professional for advice on managing depression in people with AD. People who notice depressive symptoms in their loved ones with AD should inform their doctors for further evaluation and treatment.

Learn more about dementia and AD in our dedicated hub.