Key Cognitive Disorders

Why This Matters

Cognitive disorders sit at the intersection of everything you'll study in cognitive psychology—attention, memory, executive function, perception, and emotion regulation. When these systems break down, we gain powerful insights into how they normally work. You're being tested not just on symptom lists, but on understanding which cognitive processes are disrupted and why specific treatments target those mechanisms. These disorders also demonstrate how biological substrates (neurotransmitters, brain structures) interact with cognitive functions to produce behavior.

Think of each disorder as a natural experiment revealing how the mind works. Alzheimer's teaches us about memory consolidation; ADHD illuminates attentional control; schizophrenia shows what happens when reality monitoring fails. Don't just memorize diagnostic criteria—know what cognitive mechanism each disorder disrupts and how that explains the symptoms you observe.

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Neurodegenerative Disorders

These conditions involve progressive deterioration of brain tissue, leading to cumulative cognitive decline. The key mechanism is neuronal death and the disruption of neural networks that support memory, reasoning, and daily functioning.

Alzheimer's Disease

• Progressive memory loss beginning with recent events—the hippocampus is affected early, explaining why patients retain distant memories longer than new ones
• Amyloid plaques and tau tangles accumulate in brain tissue, disrupting synaptic communication and eventually causing neuronal death
• No cure exists, but cholinesterase inhibitors can temporarily slow symptom progression by boosting acetylcholine levels in remaining neurons

Dementia

• An umbrella term for severe cognitive decline, not a single disease—Alzheimer's accounts for 60-80% of cases, but vascular dementia and Lewy body dementia have distinct mechanisms
• Core deficits span multiple domains: memory, language, executive function, and visuospatial processing, depending on which brain regions are affected
• Risk factors include age, genetics, and modifiable lifestyle factors—cardiovascular health, cognitive engagement, and social connection may offer some protection

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Neurodevelopmental Disorders

These conditions emerge during brain development, typically manifesting in childhood. They reflect atypical neural wiring that affects how individuals process information, regulate attention, and navigate social environments.

Attention Deficit Hyperactivity Disorder (ADHD)

• Impaired executive function—specifically deficits in sustained attention, impulse control, and working memory linked to prefrontal cortex underactivity
• Dopamine dysregulation explains why stimulant medications (which increase dopamine availability) paradoxically calm hyperactive symptoms
• Persists into adulthood in approximately 60% of cases, though hyperactivity often decreases while inattention and executive dysfunction remain

Autism Spectrum Disorder

• Challenges in social cognition and communication—often linked to differences in theory of mind, the ability to infer others' mental states
• The "spectrum" designation reflects enormous variability, from individuals requiring substantial support to those with exceptional abilities in specific domains
• Early intervention dramatically improves outcomes, particularly therapies targeting social skills, communication, and adaptive behavior during critical developmental windows

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Mood Disorders

These conditions primarily disrupt emotional regulation, but they significantly impair cognitive functions like concentration, memory encoding, and decision-making. The cognitive symptoms often persist even when mood improves.

Depression

• Persistent low mood combined with cognitive deficits—patients show impaired concentration, slowed processing speed, and negative memory bias (recalling negative events more readily)
• Neurotransmitter imbalances in serotonin, norepinephrine, and dopamine systems underlie both emotional and cognitive symptoms
• High comorbidity with other disorders complicates both diagnosis and treatment—depression frequently co-occurs with anxiety, PTSD, and chronic medical conditions

Bipolar Disorder

• Alternating manic and depressive episodes create distinct cognitive profiles—mania involves racing thoughts, impaired judgment, and distractibility; depression mirrors unipolar depression's cognitive slowing
• Mood stabilizers like lithium work partly by modulating neurotransmitter systems and protecting against neuronal damage during episodes
• Executive function deficits persist between episodes, suggesting the disorder involves ongoing cognitive vulnerability, not just mood dysregulation

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Anxiety-Related Disorders

These conditions involve hyperactive threat-detection systems, leading to excessive fear responses and cognitive patterns like rumination, hypervigilance, and avoidance. Attention becomes biased toward perceived threats.

Anxiety Disorders

• Attentional bias toward threat—anxious individuals show faster detection of threatening stimuli and difficulty disengaging attention from potential dangers
• Multiple subtypes exist: generalized anxiety (chronic worry), panic disorder (sudden intense fear), and social anxiety (fear of evaluation), each with distinct cognitive patterns
• Cognitive-behavioral therapy (CBT) effectively treats anxiety by restructuring maladaptive thought patterns and reducing avoidance behaviors

Obsessive-Compulsive Disorder (OCD)

• Intrusive obsessions trigger compulsive rituals—the cognitive mechanism involves impaired inhibition and an inflated sense of responsibility for preventing harm
• Exposure and response prevention (ERP) is the gold-standard treatment, working by breaking the reinforcement cycle between obsessions and compulsions
• Neuroimaging reveals hyperactivity in the orbitofrontal cortex and anterior cingulate cortex, brain regions involved in error detection and behavioral monitoring

Post-Traumatic Stress Disorder (PTSD)

• Trauma memories become fragmented and intrusive—the amygdala's fear response overwhelms hippocampal processing, preventing proper memory consolidation
• Flashbacks represent involuntary memory retrieval triggered by sensory cues, demonstrating how emotional memories can bypass normal conscious recall
• Trauma-focused therapies like EMDR and prolonged exposure help by reprocessing traumatic memories and reducing their emotional intensity

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Psychotic Disorders

Psychosis involves a fundamental break from shared reality, with disruptions in perception, belief formation, and thought organization. These conditions reveal how the brain normally constructs and monitors our experience of reality.

Schizophrenia

• Positive symptoms add experiences: hallucinations (perceiving stimuli that aren't there) and delusions (fixed false beliefs) reflect failures in reality monitoring and source attribution
• Negative symptoms subtract function: flat affect, social withdrawal, and reduced motivation suggest disrupted reward processing and executive function
• Dopamine hypothesis remains central—antipsychotic medications work primarily by blocking dopamine receptors, though glutamate and other systems are also implicated

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Quick Reference Table

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Self-Check Questions

1. Both Alzheimer's disease and depression can cause memory problems. How do the underlying mechanisms differ, and how would you distinguish them clinically?

2. Which two disorders involve disrupted executive function as a core feature, and what specific executive processes are impaired in each?

3. Compare and contrast the attentional biases seen in ADHD versus anxiety disorders. How does attention malfunction differently in each condition?

4. If an FRQ asks you to explain how cognitive-behavioral therapy works, which disorders would provide the best examples, and what cognitive mechanisms does CBT target?

5. Schizophrenia and bipolar disorder can both involve psychotic symptoms. What key difference in the timing and context of psychosis distinguishes these two disorders?