What is Depressive Cognitive Disorders ?
Depressive cognitive disorders, sometimes referred to as pseudodementia, involve cognitive and functional impairments that mimic neurodegenerative disorders due to mental health symptoms. While these symptoms, which include issues with thinking and decision making, used to be overlooked, doctors and researchers now pay more attention to them. This is because it’s been discovered that cognitive symptoms tied to depression can persist even after mood symptoms have subsided, potentially evolving into true dementia over time. These cognitive struggles can severely affect daily functioning and heighten the risk of experiencing further depressive episodes.
Since the 1980s, depressive cognitive disorders have been seen as a type of dementia that can be reversed and treated. It also became clear in the 1990s that depression with cognitive distortion could be an early sign of irreversible dementia. Recent research further suggests a strong link between depressive disorders and a higher risk of developing true dementia. Therefore, if depression and cognitive impairment are present together, it often indicates oncoming dementia and doctors should start diagnostic procedures. Some, however, argue that the term pseudodementia is misleading and inappropriate.
According to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), issues with thinking, concentrating, and decision making are understood as primary symptoms of depression. However, it does not formally recognize reversible dementia due to neuropsychiatric disorders. The situation gets trickier with elderly patients, who can exhibit either initial signs of a mood disorder with cognitive disruptions, or signs of dementia with depressive symptoms. This makes it challenging to differentiate between the two, especially since cognitive impairment often persists even when the depressive phase is over.
In the elderly, symptoms of mania are not as easily recognized as in younger patients and are often misdiagnosed as dementia. This misdiagnosis is due to symptoms like fast speech and hyperactivity often seen in older manic patients.
While the term pseudodementia has its critics, its underlying idea encourages every doctor to consider depression as a possible cause when diagnosing a patient with dementia-like symptoms, and vice versa. Despite pseudodementia’s usefulness in initiating discussion on potential treatable mental health symptoms, it has drawbacks. For example, it forces a strict categorization of patients as having either an organic disorder or a functional impairment, but many patients have elements of both. As a result, this term is not favored in clinical settings today. Instead, it is suggested to replace ‘pseudodementia’ with ‘cognitive impairment’.
What Causes Depressive Cognitive Disorders ?
Long-term inflammation can lead to problems with thinking and memory in people with depression. This can show up in two ways – as ‘depressive cognitive disorders’ or as ‘Wernicke pseudodementia,’ which is a more severe form.
Depression is the main reason why older people experience memory loss. There are many factors that can cause these so-called depressive cognitive disorders:
* The Serotonin Hypothesis: This idea forms the basis for how we treat serious depression and the memory issues that come with it. The theory suggests that a certain type of serotonin receptor called 5-HT-1B may play a key role in causing depression. Studies have found that these receptors don’t work properly in people with depression.
* Brain Pathways: Memory and learning are linked to complex networks in the brain, including the amygdala and its connections to areas in the frontal and temporal lobes. Serious depression can impact these brain structures (particularly the amygdala and hippocampus), leading to memory problems and difficulties with verbal learning.
* Hormonal Factors: High levels of the hormone cortisol are found in people with depression, and this has been linked to brain cell loss in the hippocampus and cognitive problems.
* Genetics: Certain genetic markers on chromosome 9 can be found in people with depressive cognitive disorders. These markers have also been associated with forms of dementia, which shows a genetic link between these disorders.
* Social and Environmental Factors: Things like past abuse, not having social support, job loss, negative life experiences, and substance abuse can cause stress. This alters a key hormone regulatory system in the brain and can lead to depression and cognitive problems.
Risk Factors and Frequency for Depressive Cognitive Disorders
Depression is quite common in the elderly, affecting between 30 and 45% of this population. Of these, 10 to 12% are admitted into acute care settings, like hospitals, and 12 to 14% are admitted to nursing homes. An interesting element is that between 85 and 94% of these patients experience cognitive impairment, like memory loss, during a depressive episode, and this continues on a level of 39 to 44% even after recovery from depression.
In addition, it’s worth noting that depression accompanies neurodegenerative dementia, a decrease in mental ability severe enough to interfere with daily life, in 15 to 23% of cases. Research has even found that 20 to 30% of people with depression have deficits in executive functions, which include management skills such as paying attention, planning, problem-solving, and organization.
- Depression affects 30 to 45% of the elderly population.
- 10 to 12% are admitted to acute care settings and 12 to 14% are admitted to nursing homes.
- During a depressive episode, 85 to 94% of elderly individuals experience cognitive impairment. This continues at a rate of 39 to 44% after recovery.
- Depression is seen in 15 to 23% of cases with neurodegenerative dementia.
- Research indicates a deficit in executive functions, like planning and problem-solving, in 20 to 30% of individuals with depression.
Signs and Symptoms of Depressive Cognitive Disorders
Diagnosing depression in individuals with dementia can be complex due to various factors. These include symptoms that can occur in both conditions, symptom continuation challenges, communication difficulties in severe dementia, and the reliability of caregiver opinions. It’s crucial to conduct a comprehensive review of the patient’s history and a thorough mental status examination.
Some of the shared symptoms between depression and dementia can include a lack of interest in pleasurable activities, changes in sleep, appetite fluctuations, altered psychomotor activity, difficulty with concentration, and low energy levels. If these symptoms, particularly altered sleep patterns or lack of motivation, become more severe quickly, it could suggest that depression is also present alongside dementia. Given that severe dementia can affect communication, it can be challenging to establish a history of depressive symptoms. In these instances, a caregiver’s history and careful observation during an examination become essential for diagnosis. Additionally, some dementia patients might deny their disability (anosognosia), further complicating the reporting and identification of depression-related symptoms.
Though caregivers can offer valuable insights, their feedback can also complicate the diagnostic process as they might be dealing with their own stresses and depression. There is a strong association between depression in dementia patients and the emotional toll of caregiving.
There are several clues which can help diagnose depression in dementia patients. These include:
- Acute or subacute changes in symptoms
- Symptoms of hopelessness, helplessness, guilt, death wishes, suicidal ideation
- Signs like frequent moans, a saddening appearance, sudden changes in psychomotor activity (agitation or slowness)
- Frequent screaming with depressive content, refusal to eat
- Past history and family history of depression
- Significant complaints of memory loss and related distress.
Mental status examinations, neurocognitive tests, and laboratory tests are also necessary to rule out other medical causes. It’s key to observe a patient’s behavior during the examination. Depressed individuals often lack motivation, need more time to complete tasks, and report frequent attention or concentration problems. They are usually apathetic and easily distracted. Patients with depression often emphasize memory difficulties and associated distress, while those with dementia may appear less distressed and less aware of their cognitive deficits.
When asked questions about orientation, attention, concentration, memory, calculation, abstraction, and judgment, depressed patients typically do not respond or will reply with “I don’t know.” This can also aid in the diagnosis of depression alongside dementia.
Testing for Depressive Cognitive Disorders
In investigating potential causes for memory loss or other cognitive issues, several methods can be used. Alongside a medical history and mental status examination, doctors may also request lab tests. These tests could check for conditions such as HIV, syphilis, vitamin B12 and folate deficiency or paraneoplastic syndromes that might be contributing to cognitive problems.
Neuropsychological tests are another important tool. They can provide detailed information about memory, language skills, attention levels and more. Frequently used tests include the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), the Wechsler Memory Scale (WMS), clock drawing test, and the Trail Making test. The RBANS, for instance, examines immediate and delayed memory, attention, language, and spatial skills. It helps to identify and describe dementia and other neurocognitive deficits. Meanwhile, the WMS assesses the performance in seven areas related to memory.
Neuroimaging scans like an MRI (Magnetic Resonance Imaging), PET (Positron Emission Tomography), or SPECT (Single Photon Emission Computed Tomography) may be used as well. These imaging studies can help pinpoint specific brain abnormalities that might be seen in cases of dementia.
Lastly, rating scales can be used to screen for depression in dementia. A popular one is the Cornell Scale for Depression in Dementia (CSDD). This 19-item test uses information from both the patient and caretaker to evaluate signs related to mood, behavior, physical symptoms, daily function, and ideational disturbance. Scores over ten may suggest possible major depression, while scores above 18 can indicate a definite major depressive disorder.
Treatment Options for Depressive Cognitive Disorders
Pharmacological Treatment
Selective Serotonin Reuptake Inhibitors (SSRIs) are often the initial treatment for depression in individuals with dementia. They are generally well-tolerated, causing fewer cholinergic side effects, which can exacerbate cognitive issues. However, they can lead to some side effects including lowered sodium levels, restlessness, diminished appetite, slow heart rate, and symptoms like nausea, anxiety, and changes in sleep patterns.
If SSRIs don’t work or aren’t tolerated, Serotonin-Norepinephrine Reuptake Inhibitors (SNRI) are often the next option. Examples include venlafaxine, desvenlafaxine, and duloxetine. They’re generally safe for older individuals, but some people might experience side effects such as nausea, dizziness, insomnia, and constipation.
Tricyclic Antidepressants (TCAs) are usually avoided for those with cognitive impairment because they can magnify cognitive difficulties by blocking certain receptors in the brain.
Zolmitriptan and Vortioxetine are two other medications used in treating depressive symptoms and associated cognitive impairment. Side effects may include feelings of numbness, drowsiness and those similar to SSRIs.
Cholinesterase Inhibitors (Donepezil, galantamine, rivastigmine) are medicines that can assist with the symptoms of depression in dementia patients and also improve cognition.
Non-Pharmacological Treatment
Electroconvulsive Therapy (ECT) is a safe and effective strategy for treating depression and related cognitive deficits. It can cause confusion but this side effect can be reduced by adjusting the frequency of treatment.
Interpersonal/Behavioral Approaches can considerably improve depressive symptoms in patients and their relatives, with therapy for caregivers being a crucial part of this treatment process.
Healthy habits can also play a significant role in managing depression. Eating a healthy diet, regular exercise such as yoga, and taking omega-3 fatty acids can all contribute to decreased depressive symptoms. Among other benefits, Omega-3 fatty acids can help regulate mood and have anti-inflammatory effects.
What else can Depressive Cognitive Disorders be?
When someone experiences signs of dementia, there may be several possible causes:
- Major depressive disorder, often characterized by cognitive issues like memory loss.
- Neurodegenerative dementia, which affects different brain functions and behaviors. It’s important for doctors to conduct thorough examinations and cognitive tests before confirming this diagnosis.
- Bipolar disorder in later stages of life. Some symptoms, such as sleeplessness, easily getting distracted, irritability, low energy, and loss of interest in enjoyable activities, might be present and resembling dementia characteristics.
- Delirium, which can result from drug withdrawal (from substances such as alcohol, barbiturates, steroids), metabolic abnormalities (like problems with the thyroid or body’s fluid and electrolyte balance), or infections (such as urinary tract infections, lung infections, meningitis, or encephalitis).
- Structural brain abnormalities – these could include a tumor or a subdural hematoma (this is a buildup of blood in the brain), or a condition called normal pressure hydrocephalus. Symptoms commonly involve sudden onset and can include headaches (especially when a tumor is causing the symptoms). Also, diseases like Parkinson’s and normal pressure hydrocephalus often cause difficulties with walking, evidenced by a shuffling gait.
In any of these cases, it is essential for doctors to consider all possible explanations and conduct necessary tests to get the right diagnosis.
What to expect with Depressive Cognitive Disorders
The outlook for cognitive disorders related to depression is a subject of debate. Some studies suggest that these conditions can evolve into permanent, neurodegenerative dementia— a disease that causes ongoing decline in mental function, while others suggest this transformation doesn’t occur.
In the past, it’s been observed that depression linked with cognitive deficits may be a warning sign for developing dementia. Recent research shows that depression could double the risk of evolving into irreversible dementia.
Studies also found that over a period of 4 to 5 years, more than 70% of individuals initially diagnosed with depression along with cognitive impairment developed into dementia. Interestingly, 18% of these cases began with no noticeable cognitive changes.
Possible Complications When Diagnosed with Depressive Cognitive Disorders
Depressive cognitive disorders, such as depression and dementia, can cause significant life disruption and often lead to serious consequences. This condition not only worsens functional issues and causes longer hospital stays, but also creates challenges in managing daily life activities. If both depression and dementia are present in a person, they likely use healthcare facilities and nursing homes more than those with only one of these conditions.
The responsibility on caregivers increases dramatically when they are caring for patients dealing with both depression and dementia. Additionally, suffering from these cognitive disorders can heighten the risk of suicidal thoughts. This risk is particularly high in older, divorced or separated white men. Other risks presented by these conditions include social withdrawal and the heightened possibility of falling ill due to other medical conditions.
Having depression paired with dementia also increases the likelihood of additional medical problems in older people, such as:
- Heart diseases
- Diabetes
- Stroke
Preventing Depressive Cognitive Disorders
As the elderly population continues to grow, so does the number of older individuals struggling with mental health issues. These can include conditions like dementia and depression which begin later in life. These disorders don’t just create challenges for those experiencing them, but they also negatively impact their quality of life and put additional responsibility on the shoulders of those caring for them.
Depression-related cognitive disorders, dementia caused by damage to the brain, and late-onset depression all play significant roles in reducing the quality and length of life among older individuals. Therefore, aging greatly influences public health and social care services.
Understanding the symptoms and signs of depressive cognitive disorders is extremely important not just for those suffering from these conditions, but also for their caregivers. By recognizing these signs early on, they can quickly seek professional help, minimizing their risks and ensuring a better quality of life.
