Parkinson's disease dementia (PDD) is dementia that is associated with Parkinson's disease (PD). [1] Together with dementia with Lewy bodies (DLB), it is one of the Lewy body dementias characterized by abnormal deposits of Lewy bodies in the brain. [2] [3] [4] [5]
Parkinson's disease starts as a movement disorder, but progresses in most cases to include dementia and changes in mood and behavior. [6] The signs, symptoms and cognitive profile of PDD are similar to those of DLB; [2] DLB and PDD are clinically similar after dementia occurs in Parkinson's disease. [5] Parkinson's disease is a risk factor for PDD; it speeds up decline in cognition leading to PDD. [2] Up to 78% of people with PD have dementia. [2] Delusions in PDD are less common than in DLB, [2] and persons with PD are typically less caught up in their visual hallucinations than those with DLB. [7] There is a higher incidence of tremor at rest in PD than in DLB, and signs of parkinsonism in PDD are less symmetrical than in DLB. [8]
Parkinson's disease dementia can only be definitively diagnosed after death with an autopsy of the brain. [6] The 2017 Fourth Consensus Report established diagnostic criteria for PDD and DLB. [9] The diagnostic criteria are the same for both conditions, except that PDD is distinguished from DLB by the time frame in which dementia symptoms appear relative to parkinsonian symptoms. DLB is diagnosed when cognitive symptoms begin before or at the same time as parkinsonism. Parkinson's disease dementia is the diagnosis when Parkinson's disease is well established before the dementia occurs; that is, the onset of dementia is more than a year after the onset of parkinsonian symptoms. [9]
Cognitive behavioral therapy can help people with Parkinson's disease with parkinsonian pain, insomnia, depression, anxiety, and impulse disorders, if those interventions are properly adapted to the motor, cognitive and executive dysfunctions seen in Parkinson's disease, including Parkinson's dementia. [10]
General awareness about LBD lags well behind that of Parkinson's and Alzheimer's diseases, even though LBD is the second most common dementia, after Alzheimer's. [11]
Dementia is a syndrome associated with many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person's ability to perform everyday activities. This typically involves problems with memory, thinking, behavior, and motor control. Aside from memory impairment and a disruption in thought patterns, the most common symptoms of dementia include emotional problems, difficulties with language, and decreased motivation. The symptoms may be described as occurring in a continuum over several stages. Dementia ultimately has a significant effect on the individual, their caregivers, and their social relationships in general. A diagnosis of dementia requires the observation of a change from a person's usual mental functioning and a greater cognitive decline than might be caused by the normal aging process.
Parkinsonism is a clinical syndrome characterized by tremor, bradykinesia, rigidity, and postural instability. Both hypokinetic as well as hyperkinetic features are displayed by Parkinsonism. These are the four motor symptoms found in Parkinson's disease (PD) – after which it is named – dementia with Lewy bodies (DLB), Parkinson's disease dementia (PDD), and many other conditions. This set of symptoms occurs in a wide range of conditions and may have many causes, including neurodegenerative conditions, drugs, toxins, metabolic diseases, and neurological conditions other than PD.
Dementia with Lewy bodies (DLB) is a type of dementia characterized by changes in sleep, behavior, cognition, movement, and regulation of automatic bodily functions. Memory loss is not always an early symptom. The disease worsens over time and is usually diagnosed when cognitive impairment interferes with normal daily functioning. Together with Parkinson's disease dementia, DLB is one of the two Lewy body dementias. It is a common form of dementia, but the prevalence is not known accurately and many diagnoses are missed. The disease was first described on autopsy by Kenji Kosaka in 1976, and he named the condition several years later.
Lewy body dementia (LBD) is an umbrella term for two similar and common subtypes of dementia: dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD). Both are characterized by changes in thinking, movement, behavior, and mood. The two conditions have similar features and may have similar causes, and are believed to belong on a spectrum of Lewy body disease that includes Parkinson's disease. As of 2014, they were more often misdiagnosed than any other common dementia.
Rapid eye movement sleep behavior disorder or REM sleep behavior disorder (RBD) is a sleep disorder in which people act out their dreams. It involves abnormal behavior during the sleep phase with rapid eye movement (REM) sleep. The major feature of RBD is loss of muscle atonia during otherwise intact REM sleep. The loss of motor inhibition leads to sleep behaviors ranging from simple limb twitches to more complex integrated movements that can be violent or result in injury to either the individual or their bedmates.
Lewy bodies are the inclusion bodies – abnormal aggregations of protein – that develop inside neurons affected by Parkinson's disease (PD), the Lewy body dementias, and some other disorders. They are also seen in cases of multiple system atrophy, particularly the parkinsonian variant (MSA-P).
Cognitive disorders (CDs), also known as neurocognitive disorders (NCDs), are a category of mental health disorders that primarily affect cognitive abilities including learning, memory, perception, and problem-solving. Neurocognitive disorders include delirium, mild neurocognitive disorders, and major neurocognitive disorder. They are defined by deficits in cognitive ability that are acquired, typically represent decline, and may have an underlying brain pathology. The DSM-5 defines six key domains of cognitive function: executive function, learning and memory, perceptual-motor function, language, complex attention, and social cognition.
Parkinson-plus syndromes (PPS) are a group of neurodegenerative diseases featuring the classical features of Parkinson's disease with additional features that distinguish them from simple idiopathic Parkinson's disease (PD). Parkinson-plus syndromes are either inherited genetically or occur sporadically.
Corticobasal degeneration (CBD) is a rare neurodegenerative disease involving the cerebral cortex and the basal ganglia. CBD symptoms typically begin in people from 50 to 70 years of age, and typical survival before death is eight years. It is characterized by marked disorders in movement and cognition, and is classified as one of the Parkinson plus syndromes. Diagnosis is difficult, as symptoms are often similar to those of other disorders, such as Parkinson's disease, progressive supranuclear palsy, and dementia with Lewy bodies, and a definitive diagnosis of CBD can only be made upon neuropathologic examination.
Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease of mainly the central nervous system that affects both the motor and non-motor systems of the body. The symptoms usually emerge slowly, and, as the disease progresses, non-motor symptoms become more common. Usual symptoms include tremors, slowness of movement, rigidity, and difficulty with balance, collectively known as parkinsonism. Parkinson's disease dementia, falls and neuropsychiatric problems such as sleep abnormalities, psychosis, mood swings, or behavioral changes may also arise in advanced stages.
Signs and symptoms of Parkinson's disease are varied. Parkinson's disease affects movement, producing motor symptoms. Non-motor symptoms, which include dysautonomia, cognitive and neurobehavioral problems, and sensory and sleep difficulties, are also common. When other diseases mimic Parkinson's disease, they are categorized as parkinsonism.
Synucleinopathies are neurodegenerative diseases characterised by the abnormal accumulation of aggregates of alpha-synuclein protein in neurons, nerve fibres or glial cells. There are three main types of synucleinopathy: Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Other rare disorders, such as various neuroaxonal dystrophies, also have α-synuclein pathologies. Additionally, autopsy studies have shown that around 6% of sporadic Alzheimer's Disease exhibit α-synuclein positive Lewy pathology, and are sub-classed as Alzheimer's Disease with Amygdalar Restricted Lewy Bodies (AD/ALB).
Early onset dementia or young onset dementia refers to dementia with symptom onset prior to age 65. This condition is a significant public health concern, as the number of individuals with early onset dementia is increasing worldwide.
Visual selective attention is a brain function that controls the processing of retinal input based on whether it is relevant or important. It selects particular representations to enter perceptual awareness and therefore guide behaviour. Through this process, less relevant information is suppressed.
The Dementia with Lewy Bodies Consortium is an international multidisciplinary collaboration of researchers interested in the dementia with Lewy bodies. It first convened in Newcastle upon Tyne, England, in October 1995. Between 1995 and 2005, it issued three DLBC Consensus Reports on dementia with Lewy bodies.
Corticobasal syndrome (CBS) is a rare, progressive atypical Parkinsonism syndrome and is a tauopathy related to frontotemporal dementia. CBS is typically caused by the deposit of tau proteins forming in different areas of the brain.
In medicine, the cingulate island sign is a finding on FDG-PET brain scans that metabolism in the posterior cingulate cortex is preserved. It can help to identify dementia with Lewy bodies (DLB) and distinguish it from Alzheimer's disease and other dementias.
The REM Sleep Behavior Disorder Single-Question Screen (RBD1Q) is a one-question screening tool for dream enactment behaviors associated with the parasomnia REM sleep behavior disorder (RBD). It screens for RBD with a simple yes/no response.
Ian G. McKeith is a professor of Old Age Psychiatry at Newcastle University in Newcastle upon Tyne in the North-East of England. He is a Fellow of the Royal Society of Biology and a Fellow of the Academy of Medical Sciences.
Rapid eye movement sleep behaviour disorder and Parkinson's disease is rapid eye movement sleep behavior disorder (RBD) that is associated with Parkinson's disease. RBC is linked genetically and neuropathologically to α- synuclein, a presynaptic neuronal protein that exerts deleterious effects on neighbouring proteins, leading to neuronal death. This pathology is linked to numerous other neurodegenerative disorders, such as Lewy body dementias, and collectively these disorders are known as synucleinopathies. Numerous reports over the past few years have stated the frequent association of synucleinopathies with REM sleep behaviour disorder (RBD). In particular, the frequent association of RBD with Parkinson's. In the general population the incidence of RBD is around 0.5%, compared to the prevalence of RBD in PD patients, which has been reported to be between 38% and 60%. The diagnosis and symptom onset of RBD typically precedes the onset of motor or cognitive symptoms of PD by a number of years, typically ranging anywhere from 2 to 15 years prior. Hence, this link could provide an important window of opportunity in the implementation of therapies and treatments, that could prevent or slow the onset of PD.