Most know depression as a mood disorder that goes along with a host of emotional issues.

However, it can also negatively affect our cognitive functions, often referred to as “cognitive fog” or “brain fog.”

This is how depression impacts mental abilities:

1. Memory problems

• • Short-term memory: Depressed individuals often have trouble retaining new information or recalling recent events. This is due to disruptions in brain regions like the hippocampus, which is involved in memory formation.
    Unfortunately, depression has been linked to a reduced hippocampal volume, possibly due to elevated levels of the stress hormone cortisol.
  • Autobiographical memory: They may also experience overgeneralized memories where they have trouble recalling specific events and instead remember vague, general memories like “I always mess things up” rather than a particular incident.

2. Attention and focus

• • Mental issues can make it difficult to concentrate, sustain attention, or focus on tasks. This is often why people with depression find it hard to read or hold prolonged conversations.
    Prefrontal cortex dysfunction is a key factor here, since this area of the brain is crucial for maintaining attention and decision-making.

3. Executive functioning
   
   

• • Depression can impair executive functions like planning, organizing, problem-solving, and controlling impulses. This makes it hard for individuals to prioritize tasks, make decisions, or adapt to new situations.
    This worsened executive functioning is often tied to reduced activity in the dorsolateral prefrontal cortex, which is crucial for these high-level cognitive processes.

4. Processing speed

• • Individuals going through psychological struggles regularly experience a slowdown in processing speed, meaning they may take longer to think through problems, react to situations, or complete tasks.
    That’s partly explained by the brain’s decreased dopamine activity, influencing both motivation and cognitive agility.

5. Language and verbal fluency

• • Even language skills can be disturbed, with some individuals experiencing reduced verbal fluency that manifests itself as difficulty finding the right words or slowing down in speech.
    Studies have shown that depression can influence language processing by impacting the left hemisphere of the brain.

6. Reduced cognitive flexibility

• • Cognitive flexibility refers to the brain’s ability to switch between thinking about different concepts or adapting to new information.
    Psychological problems can make individuals “mentally rigid,” meaning they may struggle to adjust to changes, shift perspectives, or come up with alternative solutions to problems.
    This mental firmness can contribute to negative thought patterns and rumination, where individuals become stuck on the same distressing thoughts over and over.

7. Emotional reasoning
   
   

• • Depressed individuals often engage in emotional reasoning, where they interpret situations based on how they feel rather than on objective evidence.
    For example, they may believe they are genuinely worthless even when there is evidence to the contrary, when they’re feeling worthless.
    This distorted cognition can ruin the capacity to make choices and strengthen negative beliefs.

8. Impaired social cognition

• • Social cognition implies all the mental processes involved in understanding others’ emotions, intentions, and behaviors.
    Being depressed can hurt one’s ability to read social cues, empathize, or accurately perceive others’ intentions.
    This can lead to misinterpretations in social interactions, where individuals may perceive neutral or positive interactions as negative or even hostile.

9. Reduced problem-solving ability
   

• • Struggling with psychological issues regularly makes it harder to break down problems into manageable steps or to generate solutions due to damaged executive functioning and poor cognitive flexibility.
    The inability to solve problems effectively can create a sense of hopelessness, where even minor challenges feel insurmountable.

10. Overgeneralization in thinking

• • Overgeneralization is a thinking distortion where someone views a single negative event as part of an endless pattern of defeat.
    For instance, failing at one task may lead them to think, “I always fail at everything.” This way of thinking can reduce motivation and increase self-doubt.

11. Altered reward processing

• • Depression can make it difficult to experience pleasure or motivation (a condition known as anhedonia) by dampening the brain’s reward system.
    This not only affects mood, but also the capability to learn and respond to positive reinforcement, which is essential for adaptive behaviors and goal-directed actions. That’s because the dopamine system, which plays a crucial role in motivation and reward, is regularly deregulated in depression.

12. Self-focused attention (rumination)
    
    

• • People with mental illnesses frequently engage in rumination, where they overly focus on their problems and failures.
    This self-focused attention makes it hard to concentrate on external tasks because the brain becomes preoccupied with internal negative thoughts.
    Rumination is associated with reduced activation of the default mode network (DMN) and can worsen intellectual deficits by turning mental resources away from constructive activities.

13. Visual and spatial perception

• • While less common, some people with depression might experience difficulties with visual perception or spatial awareness. They may misjudge distances or struggle to navigate through environments.
    These issues are thought to be related to dysfunction in the parietal lobe.

14. Decision-making bias

• • Depression can make individuals more prone to indecision, avoidance, or overly pessimistic judgments by twisting decision-making and highlighting potential negative outcomes or risks.
    This bias is often driven by an overactive amygdala (linked to threat perception) and underactive prefrontal regions (linked to rational decision-making).

15. Sleep-related cognitive deficits
    
    

• • Going through emotional difficulties is often accompanied by sleep disturbances, such as insomnia or hypersomnia.
    Poor sleep quality can aggravate issues like memory recall, attention, and emotional regulation.
    A lack of restorative sleep changes the brain’s ability to establish memories and clear out toxins, leading to reduced cognitive efficiency during waking hours.

Long-term effects on the brain

• Chronic depression is associated with structural changes in the brain, such as:
  • Hippocampal atrophy: Reduced volume in the hippocampus, which can lead to memory issues.
  • Prefrontal cortex shrinkage: This can impair executive functioning and decision-making abilities.
  • Increased amygdala activity: Heightened emotional reactivity and threat awareness.

The mechanisms behind cognitive impairment in depression

• Neurotransmitter imbalance: Depression is associated with imbalances in neurotransmitters that play a role in thinking, like serotonin, norepinephrine, and dopamine.
• Neuroinflammation: Chronic inflammation in the brain can impair the functioning of neurons and lead to cerebral deficits.
• Neuroplasticity: Depression may influence neuroplasticity and thus cognitive flexibility by reducing the brain’s ability to form new neural connections.
• Sleep disruptions: Many people with mood disorders experience sleep problems, possibly affecting their intellectual performance, since sleep is crucial for memory consolidation and cognitive processing.

Impact on daily life

• These cognitive impairments can be devastating by affecting a person’s ability to work, study, or even engage in social activities.
  This can lead to a vicious cycle where the struggle to perform simple daily tasks worsens depressive symptoms and vice versa.

Treatment and management

• Medications: Antidepressants such as SSRIs and SNRIs could help improve cognitive symptoms by addressing these neurotransmitter imbalances.
• Cognitive behavioral therapy (CBT): This form of therapy can aid individuals develop strategies to cope with cognitive deficits.
• Exercise and lifestyle changes: Positive lifestyle changes like regular physical activity, a healthy diet, and sufficient sleep can enhance intellectual performance.
• Cognitive training: Programs designed to boost attention can be beneficial for those with severe cognitive damage.

Depression is more than just a mood disorder; it profoundly impacts the brain and its ability to function effectively. Addressing these cognitive symptoms is crucial for holistic treatment and recovery.

Final thoughts

The cognitive effects of depression go way beyond “just feeling sad.” The interaction of mental damage and mood disturbances creates a pattern where cerebral deficits degrade emotional symptoms and vice versa.

Treating these mental challenges is essential for a thorough approach to treating depression. That might include cognitive rehabilitation exercises, medications, therapy, and lifestyle interventions.

Sadly, these intellectual deficits have real-world consequences, such as reduced job performance and challenges in social interactions. What’s even worse is that these cognitive issues may continue and influence long-term recovery even when mood symptoms improve.

Understanding these effects can also help those suffering from depression to recognize that their struggles are not simply a lack of willpower but are tied to complex changes in brain function.