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The purpose of this study is to examine frontal lobe function of non-dementia Parkinson's disease (PD) patients. We examined the neuropsychological and behavioral evaluation (Stroop reaction time: SRT). Target image (20%) and non-target image (80%) were presented to PD patients, healthy elderly controls, and healthy young subjects at random. We instructed subjects that the button should pressed on the target image. This study was designed to investigate the mental set under three conditions. The Stroop test, Word Fluency Test (WFT), and Geriatric Depression Scale (GDS) were used to assess cognitive function. The SRT of PD were congruent condition and incongruent condition increased compared with simple condition. The delay of a similar SRT was seen in the healthy elderly control and young groups. However, the SRT of PD patients was slower under incongruent condition than under congruent condition. It appears that PD spent time on judgment in under incongruent condition because the meaning of the character did not correspond to the color of the character. Because, there were no significant between PD and healthy elderly subjects in Stroop test, WFT, and GDS, frontal lobe function had a partial deficit. The SRT of PD was increased by the partial deficit in information processing ability in addition to movement dysfunction.

A 68-year-old woman was admitted with dysesthesia on both soles, hands and buttocks. She first noticed the dysesthesia in the left first toe two years before admission. One year before admission, serum creatine kinase and lactate dehydrogenase levels were elevated but she had no clinical symptoms suggesting myopathy. Nerve conduction study showed no apparent abnormalities, and an electromyogram showed mild myogenic change. Computed tomography of the muscle showed fatty degeneration of the trunk, major gluteus muscle, and biceps femoris muscle and atrophic change of the biceps femoris muscle. Muscle biopsy revealed a slight variation in fiber size, the presence of cytochrome c oxidase (CCO)-negative fibers by CCO staining, ragged-red fibers by Gomori trichrome staining, and mild denervation fiber by neuron specific enolase (NSE) staining. Analysis of her mitochondrial DNA (mtDNA) revealed a large deletion of mtDNA (approximately 8.5 Kb), and mitochondrial neuromyophy was diagnosed. The frequency of mtDNA deletion increases with aging. Although her mtDNA abnormality was compatible with chronic progressive external ophthalmoplegia (CPEO), we speculate that the aging process may be contributed to the mtDNA abnormality, which would be related to the late onset of her symptoms. As the phenotype of this mitochondrial disorder shows a wide variation and mtDNA abnormality is more frequent among elderly people, we should consider the possibility of mitochondrial disorders even in elderly people.

The Cognitive Abilities Screening Instrument (CASI) was developed by Japanese and American researchers, including the authors, to examine cognitive functions, based on previous neuropsychological tests, such as Hasegawa's Dementia Scale and the MMSE. From the Adult Health Study (AHS) population of the Radiation Effects Research Foundation, 2052 men and women aged 60 or over and living in Hiroshima were evaluated for their cognitive functions using the CASI. Dementia was diagnosed in 93 and 1,959 were considered not to suffer from dementia based on the DSM-III-R criteria using neurological examination and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE) completed by caregivers. Multivariate regression analysis not only indicated that total score was higher with lower age and higher education but that the slope of its decrease is steeper with higher age and fewer years of education. The slope of score decrease with increase of age was steeper for women than for men. Furthermore, CASI items were categorized by domains of cognitive function. Multivariate regression analysis for each cognitive domain showed clear effects of age and level of education. The effect of age for the nondementia subjects was large in cognitive domains dealing with temporal orientation, short-term memory, and list-generating fluency. The most useful cognitive domains for diagnosing dementia were temporal orientation, short-term memory, and list-generating fluency, as was indicated by high sensitivity and specificity.

A 77-year-old man was admitted because of muscle weakness in both upper and lower extremities. Diabetes mellitus was diagnosed in 1988 and he had been treated by oral hypoglycemic agents. He had a common cold at the end of January, 1997. Muscle weakness appeared in the upper extremities, followed by the lower extremities at the end of February. No sensory disturbance or dysuria was recognized. Nerve conduction study revealed distally dominant demyelinating polyneuropathy. Guillain-Barré's syndrome was diagnosed and he recovered completely following immunological absorption therapy (IAT). However, he had quadriplegia again at the end of April. He was treated by IAT combined with corticosteroid and has shown no relapse. In June, 1997, gastric cancer was detected by upper gastrointestinal fiberscopy and subtotal gastrectomy was performed. Judging from this clinical course, this case seems to be chronic inflammatory demyelinating polyneuropathy (CIDP) with acute onset. Many kinds of causes often contribute to the pathogenesis of neuropathy in the elderly. So in cases of progression or worsening, we should consider such possibilities and it is necessary not to exclude treatable causes of neuropathy.

A 75-year-old man had noticed muscle atrophy and weakness of his right hand and forearm at the age of 25. The symptoms slowly progressed and then stopped. Right hand tremor appeared at about age 40. There was no symptom in his left upper extremity, and his gait was normal. He now shows severe muscle atrophy in his right hand and forearm. There was distally dominant weakness of the right upper extremity and his hand grip was 0 kg on the right and 25 kg on the left. On admission there was no weakness in the bilateral lower extremities. He had postural tremor in both hands and fingers. The tendon reflexes were hypoactive in the upper extremities and normal in the lower extremities. Abnormalities in the superficial sensation were unremarkable, whereas vibration sensation in both the upper and lower extremities was mildly disturbed. Electromyography revealed chronic denervation, especially in the right upper extremity. The sensory nerve conduction study results and somatosensory evoked potentials in the upper extremities were normal. Cervical MRI demonstrated spondylotic changes, canal stenosis from the C5 to C7 levels, and compression of the spinal cord. His hand tremor was dominant on the right with a peak frequency of about 7 Hz. Tremor frequency and power were decreased by mechanical load. Hirayama's disease (juvenile muscular atrophy of unilateral upper extremity) was the most probable diagnosis, although aging might have produced various additional abnormalities. The tremor seen in this patient showed characteristics of enhanced physiological tremor.

We investigated the effect of aging on nerve conduction parameters in 184 subjects (aged 10-75 years) without any history or signs of peripheral neuropathy, in order to clarify the diagnostic parameters of demyelinating neuropathies in the aged. The CMAP amplitude ratio (proximal CMAP/distal CMAP), duration ratio and area ratio remained unchanged throughout the second to eighth decades. The lower limits of normal CMAP amplitude ratio (mean -3SD) were 0.79 (median nerve), 0.74 (ulnar nerve), 0.59 (peroneal nerve), and 0.48 (tibial nerve). The upper limits of normal CMAP duration ratio (mean 11+ 3SD) were 1.22 (median nerve), 1.19 (ulnar nerve), 1.35 (peroneal nerve), and 1.32 (tibial nerve). The lower limits of normal CMAP area ratio (mean -3SD) were 0.84 (median nerve), 0.78 (ulnar nerve), 0.61 (peroneal nerve), and 0.62 (tibial nerve). There were no age-related changes in amplitude ratio or duration ratio of SNAP, although the standard deviations increased with age. Since the amplitude ratio, duration ratio and area ratio are simple and age-independent, they can provide useful and reliable information for routine nerve conduction studies for aged patients with demyelinating neuropathies.