Often begins in the fifth to seventh decades; in this age group it is nearly as prevalent as AD. Unlike AD, behavioral symptoms may predominate in the early stages of FTD. Extremely heterogeneous; presents with combinations of disinhibition, dementia, apraxia, parkinsonism, and motor neuron disease. May be sporadic or inherited. Treatment is symptomatic; no therapies known to slow progression or improve cognitive symptoms. Many of the behaviors that accompany FTD such as depression, hyperorality, compulsions, and irritability may be helped with SSRIs.
Characterized by visual hallucinations, parkinsonism, fluctuating alertness, falls, and often RBD. Dementia can precede or follow the appearance of parkinsonism; when it occurs after an established diagnosis of Parkinson's disease, many use the term Parkinson's disease dementia (PDD). Lewy bodies are intraneuronal cytoplasmic inclusions. Anticholinesterase compounds often provide significant benefit due to a severe cholinergic deficit in DLB. Exercise programs to maximize motor function and protect against fall-related injury, and antidepressants to treat depressive syndromes may be helpful. Antipsychotics in low doses to alleviate psychosis may be considered, although DLB pts are extremely sensitive to these agents and may experience worsening of extrapyramidal symptoms.
Typically follows a pattern of either multiple strokelike episodes (multi-infarct dementia) or diffuse white matter disease (leukoaraiosis, subcortical arteriosclerotic encephalopathy, Binswanger's disease) (Fig. 182-1). Unlike AD, focal neurologic signs (e.g., hemiparesis) may be apparent at presentation. Treatment focuses on underlying causes of atherosclerosis.
Normal-Pressure Hydrocephalus (NPH) 
Uncommon; presents as a gait disorder (ataxic or apractic), dementia, and urinary incontinence. Gait improves in some pts following ventricular shunting; dementia and incontinence do not improve. The diagnosis is difficult to make, and the clinical picture may overlap with several other causes of dementia including AD; historically many individuals treated for NPH have suffered from other dementias.
Chorea, behavioral disturbance, and a frontal/executive disorder (Chap. 54. Tremor and Movement Disorders). Typical onset fourth to fifth decade but can present at almost any age. Autosomal dominant inheritance due to expanded trinucleotide repeat in gene encoding the protein huntingtin. Diagnosis confirmed with genetic testing coupled with genetic counseling. Symptomatic treatment of movements and behaviors; SSRIs may help depression.
Prion disorders such as CJD are rare (~1 per million). CJD is a rapidly progressive disorder with dementia, focal cortical signs, rigidity, and myoclonus; death in <1 year from first symptom. The markedly abnormal periodic discharges on EEG and cortical ribboning and basal ganglia hyperintensities on diffusion-weighted and fluid-attenuated inversion recovery MRI are diagnostic features. No proven treatments exist.
For a more detailed discussion, see Seeley WW, Miller BL: Dementia, Chap. 35, p. 170, in HPIM-19; Seeley WW, Miller BL: Alzheimer's Disease and Other Dementias, Chap. 448, p. 2598, in HPIM-19. |
Outline