Cognitive impairment in DLB is often misdiagnosed as AD. While memory may be relatively intact in early DLB, the cognitive profile of DLB includes:
- Early and significant deficits in executive function, such as impaired planning, problem solving and judgment.
- Visuospatial dysfunction, resulting in difficulty recognizing familiar people or objects, problems with depth perception, or impaired hand-eye coordination.
- Reduced attention or ability to concentrate, which may mimic memory deficits.
- Slowed thinking (bradyphrenia) and speech difficulties may also occur.
- Fluctuating cognition is common and refers to changes in levels of attention, concentration and functional ability. Fluctuations may present as staring spells or confusion that lasts from minutes to hours. Transient episodes of unresponsiveness may also occur.
The onset timing of spontaneous parkinsonism in LBD varies and may be subtle at first. Signs and symptoms include:
- Reduced facial expression (masked facies)
- Soft voice (hypophonia)
- Stiffness (rigidity)
- Postural instability
- Gait difficulty and falls
- Slowness of movement (bradykinesia)
- Tremor at rest
Recurrent visual hallucinations occur in up to 80% of people with LBD, and their appearance early in the course of dementia strongly suggests LBD3. People with LBD frequently report seeing people, animals or insects and can often describe them in great detail. Delusions are also common and may relate to visual hallucinations. Apathy, anxiety and depressive symptoms and signs are also frequently seen in LBD patients. Unfortunately, a severe sensitivity to antipsychotics is also a common symptom of LBD.
REM sleep behavior disorder (RBD) may present years or even decades before other signs of LBD. RBD results from the absence of sleep paralysis that normally occurs during REM sleep, leading people to physically move about in their dreams. Patients may experience vivid nightmares and can shout, thrash, punch or kick during their dreams, sometimes injuring themselves or their bed partners. Idiopathic RBD is highly associated with the development of Lewy body disorders, both DLB and PD, but not AD.
Other sleep disorders include excessive daytime sleepiness, restless leg syndrome, insomnia, obstructive sleep apnea and periodic limb movement. A formal sleep study and treatment is recommended to resolve significant disruptions of sleep.
Severe autonomic dysfunction may occur in LBD, including orthostatic hypotension (a form of low blood pressure that happens when standing after sitting or lying down), syncope (fainting), erectile dysfunction, urinary incontinence and constipation. Other signs of autonomic dysfunction include excessive saliva and drooling (sialorrhea), altered sweating and a chronic, scaly skin condition (seborrhea). An impaired sense of smell (hyposmia) is also common, occurring earlier in LBD than in AD.