Neurobehavioral, Cognitive, and Psychiatric Sequelae of Brain Injury
Cognition, behavior, and mood after brain injury
Cognitive recovery follows a hierarchy. Attention and processing speed slow first; working memory, declarative memory, and executive functions (initiation, planning, set-shifting, self-monitoring) are most vulnerable, while language and visuospatial deficits track focal injury. Test with a screen (MoCA, RBANS, Trails, verbal fluency) plus functional measures, and retest - early testing overestimates permanent deficit.
Behavioral syndromes reflect frontal–limbic disruption: apathy, disinhibition, impulsivity, irritability, and agitation. Early agitated delirium is tracked with the Agitated Behavior Scale and is not the same as later aggression. Depression, anxiety, and PTSD commonly coexist and can mimic cognitive loss. Apathy differs from depression: no dysphoria or guilt, and a different treatment response.
Environment is the first drug: reduce noise, keep routine and cues, redirect rather than confront, and build an ABC (antecedent–behavior–consequence) plan. Address pain, constipation, sleep, and sedating medications before adding psychotropics. Pharmacologically, SSRIs treat depression, anxiety, and emotional lability; propranolol or mood stabilizers target aggression; methylphenidate helps attention and initiation; amantadine helps frontal hypoarousal; dextromethorphan/quinidine treats pseudobulbar affect. Avoid benzodiazepines and anticholinergics; antipsychotics may blunt recovery.
Trap: labeling new agitation as 'the TBI' while missing delirium from infection, withdrawal, or a new subdural collection.
Rule of thumb: behavior is a symptom - find the trigger, then treat a defined target with the shortest, simplest trial and measure it.
Worked example: three weeks post injury, escalating restlessness and therapy refusal. Check sleep, pain, bowel, and medications first; if agitation persists and is unsafe, track ABS daily and start propranolol with a stated target and stop date - not a benzodiazepine.