History and exam

Key diagnostic factors

common

presence of risk factors

A key risk factor is older age.

fluctuations

Fluctuations are a core clinical feature and may include fluctuations in cognition, attention, and arousal.[1]

visual hallucinations

Recurrent visual hallucinations are a core clinical feature.[1] They occur in up to 80% of patients with DLB. These are typically complex and may include children or small animals. Emotional responses are variable.

Typically present early in the disease.[29][30] Neuropsychiatric symptoms such as apathy, sleep disturbance, and anxiety frequently co-exist.[1][31]

motor symptoms

Spontaneous parkinsonian features, not due to antidopaminergic medications or stroke, are present in over 85% of patients with DLB, and are a core clinical feature. Parkinsonism in Parkinson's disease is defined as bradykinesia in combination with rest tremor, rigidity, or both. Many DLB patients’ parkinsonism falls short of this, so documentation of only one of these cardinal motor features is required.[1]

rapid eye movement (REM) sleep behavioural disturbance

A core clinical feature. Vivid dreams are accompanied by loss of associated atonia of REM sleep. Patients tend to act out their dreams. Vocalisation, as well as violent and unpredictable movements, may occur. However, only a small proportion of RBD events involve violent dreams and behaviours.[23] May precede cognitive decline.[1]

Other diagnostic factors

common

severe antipsychotic sensitivity

Severe antipsychotic sensitivity reactions have been reported in approximately half of patients with DLB.[1][32] Motor symptoms may worsen with concomitant changes in consciousness. Overall, there is high morbidity and mortality associated with the use of these drugs.[1]

depression

Mood disturbance is common in dementia. Neuropsychiatric symptoms such as apathy, sleep disturbance, and anxiety frequently co-exist.[1][31]

anxiety

Common in dementia. Neuropsychiatric symptoms such as apathy, sleep disturbance, and depression frequently co-exist.[1][31]

repeated falls and syncope

Due to autonomic dysfunction.[1]

orthostatic hypotension

Due to autonomic dysfunction.[32]

urinary symptoms

Due to autonomic dysfunction. Symptoms can include urgency, frequency, and incontinence.[32]

constipation

Due to autonomic dysfunction.[32]

attentional and visual processing abnormalities

A notable distinguishing feature of DLB compared with Alzheimer's disease, especially early in the disease course.[1]

delusions

Often associated with other neurobehavioural problems.[1]

hypersomnia

Usually presenting as excessive daytime sleepiness.[1]

Often associated with autonomic dysfunction.

hyposmia

Occurs earlier in DLB than in Alzheimer's disease.[1]

uncommon

auditory hallucinations

Visual hallucinations are more characteristic in DLB, but auditory hallucinations may also occur.[1]

Risk factors

strong

older age

Age is the strongest risk factor, as with all dementias. The age range for DLB is similar to that of Alzheimer's disease: that is, most cases occur in people aged between 60 and 95 years. One review of population-based prevalence studies showed that prevalence increases in studies that enrol people with increasing age.[8] 

weak

familial occurrence

Almost all DLB cases are sporadic; however, familial clusters have been reported. It is likely that genetic factors contribute to DLB pathogenesis. Most are autosomally dominantly inherited, although autosomal recessive inheritance has also been implicated.[12][13] Genes identified in families with DLB include the APOE e4 allele, alpha-synuclein gene on chromosome 4, glucocerebrosidase, and SNCA.[12][14][15]

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